CSS Grid: Border Between Each Row

CSS Grid borders

User Interface Layout with CSS

CSS Grid is a layout system that allows you to design web interfaces with rows and columns. In earlier times, developers used less elegant techniques to arrange UI elements. In the 1990s, using HTML tables was the standard way. Many of my earliest clients used tables for their entire website and email newsletter code bases. During that time Dreamweaver was a popular product that let designers build websites and generated source code that was mostly tables. The semantic problem what this approach was that we were using tables for non-tabular data.

By the 2000s, the CSS float property became popular for multi-column layouts. We didn’t see Flexbox until the mid 2010s. You can read about examples of its use in the layout of my blog  and an image carousel I built.

CSS Grid

Grid is the latest addition to the toolbox of options. For a recent project I used CSS Grid to create a two column web application. Here is some example HTML:

<h1>Below is a grid of data</h1>
<div style="display: grid; grid-template-columns:repeat(2, 1fr); grid-gap: 24px">
	<div>Row 1, Column 1</div>
	<div>Row 1, Column 2</div>

	<div>Row 2, Column 1</div>
	<div>Row 2, Column 2</div>

	<div>Row 3, Column 1</div>
	<div>Row 3, Column 2</div>
</div>

The grid container has a property: `grid-template-columns:repeat(2, 1fr);`. The CSS property grid-template-columns is used to define the number and size of columns in a CSS Grid layout. This repeat() function is used to repeat a pattern a specified number of times. In this case, the pattern is defined by the second argument, 1fr. fr stands for “fractional unit.” This property is describing two columns, with each item taking up an equal amount of space. This is what it looks like:

grid css layout

I wanted a horizontal line to separate each row. Usually, just adding a border-bottom to each of the grid items will work. In this scenario, the grid design called for a grid-gap property that forced the border to break.

css grid-gap

We fixed this by adding a new grid item between each “row” (that is, every third element). Those elements would represent each border line. I set the grid-column property of those elements to span two columns.

<style>
	.gridItemBorder{
		border-bottom: 2px solid #333;
		grid-column: span 2;
	}
</style>


<h1>Below is a grid of data</h1>
<div style="display: grid; grid-template-columns:repeat(2, 1fr); grid-gap: 24px">
	<div class="gridItem">Row 1, Column 1</div>
	<div class="gridItem">Row 1, Column 2</div>

	<div class="gridItemBorder"></div>

	<div class="gridItem">Row 2, Column 1</div>
	<div class="gridItem">Row 2, Column 2</div>

	<div class="gridItemBorder"></div>

	<div class="gridItem">Row 3, Column 1</div>
	<div class="gridItem">Row 3, Column 2</div>
</div>

The end result is just what we wanted:

css grid layout with row separators

Sort an HTML Table Using JavaScript

Sort an HTML Table Using JavaScript

For a recent side project I was tasked with enhancing an existing HTML table. That table displayed search results. The records were dynamic, populated by an AJAX call after the “search” button was pressed. One of the requests was to let users click on the column headers to sort the table. Each click would organize the data, toggling ascending and descending, based on the column values.

A table with data about dogs

My first idea was to use a front-end library. I love abstractions, and hate reinventing the wheel. I’ve used the DataTables jQuery plug-in before, and thought it might be a good fit. All I had to do was include two CDN file references – one for CSS styles and another for JavaScript functionality. After that, I could select the table by ID and call a single function:

<link href='//cdn.datatables.net/1.13.2/css/jquery.dataTables.min.css' rel='stylesheet' type='text/css'>
<script src="//cdn.datatables.net/1.13.2/js/jquery.dataTables.min.js"></script>

<script>
$(document).ready( function () {
	$('#dog-table').DataTable();
} );
</script>

This added quick and easily out-of-the-box functionality, with bells and whistles.

It seemed great, but the extras that it added, such as pagination and front-end search were unnecessary, and actually got in the way of the design specification. Those might be easy enough to clean up by passing options into the method call, or even with a bit of custom CSS, but still seemed like overkill.

Further, the DataTables library would occasionally throw errors about an “incorrect column count”, depending on what results my back-end provided. That was because the data model, and possible front-end actions for this app were more complex that you might think. The HTML wasn’t strictly semantic and the information wasn’t just tabular.

The more I thought about it, the more I felt that plain vanilla JavaScript should be enough to get the job done. And, since we’re living in the future, I decided to ask an AI chat-bot called ChatGPT.

I asked “How can I use jQuery to sort an HTML table by a specific column?”

Asking ChatGPT about coding

It told me that “You can use the sort method of JavaScript arrays combined with the map method to sort an HTML table by a specific column,” and gave me a specific code example!

I was very impressed. Here is the JavaScript code it provided:

<script>
$(document).ready(function() {
  var table = $('#myTable tbody tr').get();

  table.sort(function(a, b) {
    var A = $(a).children('td').eq(1).text();
    var B = $(b).children('td').eq(1).text();

    if(A < B) {
      return -1;
    }

    if(A > B) {
      return 1;
    }

    return 0;
  });

  $.each(table, function(index, row) {
    $('#myTable').children('tbody').append(row);
  });
});
</script>

I added this code to a click-handler in my app, after adjusting the element selectors. Although it worked (kind of), it did not operate quite as I expected. It only performed the sort on a single column, and did not alternate the order on each click.

I continued to ask the chat-bot more questions, making refinements to the functionality. I wanted the code to toggle between ascending and descending on each click. Also, I figured it could be nice to avoid jQuery completely and just use basic JS.

Chat bot solving code problems

Eventually, it told me “To toggle between ascending and descending order when sorting the table, you can keep track of the current sorting order for each column in a separate array”. Below, you can see the full code implementation:

<style>
  table {
  border-collapse: collapse;
  width: 100%;
}

th, td {
  text-align: left;
  padding: 8px;
  border-bottom: 1px solid #ddd;
}

tr:nth-child(even) {
  background-color: #f2f2f2;
}

th {
  background-color: #4CAF50;
  color: white;
  cursor: pointer;
}

td:first-child {
  font-weight: bold;
}

td:nth-child(3), td:nth-child(4) {
  text-transform: capitalize;
}
#search-input {
  padding: 8px;
  margin-bottom: 12px;
  width: 100%;
  box-sizing: border-box;
  border: 2px solid #ccc;
  border-radius: 4px;
  font-size: 16px;
}

#search-input:focus {
  outline: none;
  border-color: #4CAF50;
}
</style>
<input type="text" id="search-input" placeholder="Search breeds...">
<button>Search</button>
<table id="dog-table">
  <thead>
    <tr>
      <th>Breed</th>
      <th>Origin</th>
      <th>Size</th>
      <th>Temperament</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>Labrador Retriever</td>
      <td>Canada</td>
      <td>Large</td>
      <td>Friendly, outgoing, and active</td>
    </tr>
    <tr>
      <td>German Shepherd</td>
      <td>Germany</td>
      <td>Large</td>
      <td>Loyal, confident, and courageous</td>
    </tr>
    <tr>
      <td>Poodle</td>
      <td>France</td>
      <td>Small to Large</td>
      <td>Intelligent, elegant, and proud</td>
    </tr>
    <tr>
      <td>Bulldog</td>
      <td>England</td>
      <td>Medium</td>
      <td>Determined, friendly, and calm</td>
    </tr>
    <tr>
      <td>Beagle</td>
      <td>England</td>
      <td>Small to Medium</td>
      <td>Cheerful, determined, and friendly</td>
    </tr>
  </tbody>
</table>


<script>
// Get the table element
const table = document.querySelector('table');

// Get the header row and its cells
const headerRow = table.querySelector('thead tr');
const headerCells = headerRow.querySelectorAll('th');

// Get the table body and its rows
const tableBody = table.querySelector('tbody');
const tableRows = tableBody.querySelectorAll('tr');

// Initialize sort order for each column
let sortOrders = Array.from(headerCells).map(() => null);

// Attach a click event listener to each header cell
headerCells.forEach((headerCell, index) => {
  headerCell.addEventListener('click', () => {
    // Extract the column index of the clicked header cell
    const clickedColumnIndex = index;
    
    // Toggle the sort order for the clicked column
    if (sortOrders[clickedColumnIndex] === 'asc') {
      sortOrders[clickedColumnIndex] = 'desc';
    } else {
      sortOrders[clickedColumnIndex] = 'asc';
    }
    
    // Sort the rows based on the values in the clicked column and the sort order
    const sortedRows = Array.from(tableRows).sort((rowA, rowB) => {
      const valueA = rowA.cells[clickedColumnIndex].textContent;
      const valueB = rowB.cells[clickedColumnIndex].textContent;
      const sortOrder = sortOrders[clickedColumnIndex];
      const compareResult = valueA.localeCompare(valueB, undefined, { numeric: true });
      return sortOrder === 'asc' ? compareResult : -compareResult;
    });
    
    // Rebuild the table in the sorted order
    tableBody.append(...sortedRows);
  });
});

</script>

Using predictive language models as a coding assistant is very helpful. I can’t wait to see what other uses we find for this technology, especially as it gets better.

CSS for weighted hyperlink decoration

CSS for weighted hyperlink decoration

How to add an underline to website text should be covered in any intro to web development course. The old-fashioned HTML way uses a now-deprecated tag:

<u>This will appear underlined!</u>

Modern approaches use CSS to define such a style:

<p style="text-decoration: underline;">This will appear underlined!</p>

Even better, properly written code will separate the inline styles, like so:

<style>
.underlined-text{
  text-decoration: underline;
}
</style>
<p class="underlined-text">This will appear underlined!</p>

For hyperlink text, I might want to hide the underline when a user mouses over it. That’s easy with the “hover” pseudo-class:

<style>
a.hyperlink-text{
  text-decoration: underline;
}
a.hyperlink-text:hover{
  text-decoration: none;
}
</style>
<a class="hyperlink-text">This will appear underlined!</a>

But, suppose I want to have that underline to become thicker instead of disappearing. That will require an advanced, super-secret CSS technique. To make it work, we will utilize box-shadow.

In the world of cascading style sheets, the box-shadow property adds a shadow effect around any HTML element. The shadow is described by its offsets, relative to the element. Leveraging this, we can create a shadow that looks like an underline. On hover, we can adjust the settings to change its appearance:

<style>
a.hyperlink-text{
  text-decoration: none;
  box-shadow: inset 0 -1px 0 rgb(15 15 15);
}
a.hyperlink-text:hover{
  -webkit-box-shadow: inset 0 0 0 rgb(0 0 0 / 0%), 0 3px 0 rgb(0 0 0);
  box-shadow: inset 0 0 0 rgb(0 0 0 / 0%), 0 3px 0 rgb(0 0 0);
}
</style>
<a class="hyperlink-text">This will appear underlined!</a>

Point your cursor over any of the hyperlinks in this post to see what it looks like. Experiment with the above code to make it your own.

Radio button value checked from a database in PHP

Form input with PHP

When building software user interfaces, I create HTML forms to manage any app settings. I’ll usually have a few text and radio inputs like this:

settings input form

Using PHP, I grab a database record and access its properties to populate the form. Filling out the text inputs is straight-forward:

<?php $clickToCallRecord = $db_service->getClickToCallRecord($installation_complete_id); ?>

<div class="form-group">
    <label>Phone number:</label>
    <input class="form-control" type="tel" name="phone_number" value="<?php echo $clickToCallRecord['phone_number']; ?>" placeholder="(123)-456-7890">
</div>
<div class="form-group">
    <label>Message:</label>
    <input class="form-control" type="text" name="message_text" value="<?php echo $clickToCallRecord['message_text']; ?>" placeholder="Call Us Now">
</div>
<div class="form-group">
    <label>Background Color:</label>
    <input class="form-control" type="text" value="<?php echo $clickToCallRecord['bg_color']; ?>" name="bg_color">
</div>

Checking the correct radio input requires our code to evaluate the data value. I add a PHP variable to each of the inputs as attributes. Those variables will render to either “checked” or blank:

<?php
    $top_checked = "";
    $bottom_checked = "";
    $position = $clickToCallRecord['position'];
    if($position == "top"){
        $top_checked = "checked";
        $bottom_checked = "";
    }else{
        $top_checked = "";
        $bottom_checked = "checked";
    }

    $show_checked = "";
    $hide_checked = "";
    $display = $clickToCallRecord['display'];
    if($display == "show"){
        $show_checked = "checked";
        $hide_checked = "";
    }else{
        $show_checked = "";
        $hide_checked = "checked";
    }

?>

<div class="form-group">
    <label>Position:</label>
    <div>
        <div class="form-check form-check-inline">
          <input <?php echo $top_checked; ?> class="form-check-input" type="radio" name="position" value="top">
          <label class="form-check-label" for="matchtype">Top</label>
        </div>
        <div class="form-check form-check-inline">
          <input <?php echo $bottom_checked; ?> class="form-check-input" type="radio" name="position"  value="bottom">
          <label class="form-check-label" for="matchtype">Bottom</label>
        </div>
    </div>
</div>
<hr />
<div class="form-group">
    <label>Display:</label>
    <div>
        <div class="form-check form-check-inline">
          <input <?php echo $show_checked; ?> class="form-check-input" type="radio" name="display" value="show">
          <label class="form-check-label" for="matchtype">Show</label>
        </div>
        <div class="form-check form-check-inline">
          <input <?php echo $hide_checked; ?> class="form-check-input" type="radio" name="display"  value="hide">
          <label class="form-check-label" for="matchtype">Hide</label>
        </div>
    </div>
</div>

This example comes from a Shopify app that helps stores increase conversions by adding a UI element prompting customers to call a phone number.

How to create a Shopify app with PHP

Build a Shopify App with PHP

Developing a marketplace app for your SAAS will grow organic traffic and lets users find you. Potential customers can discover your digital product where they are already looking. Software services that occupy the eCommerce space have a chance to help Shopify store owners grow their businesses. Creating a public Shopify app benefits both developers and the merchant user-base in the Shopify App Store ecosystem.

Recently, Shopify announced that it is decreasing the share of profit that it takes from developers. Each year, developers keep all of their revenue up to the first one-million dollars.

Why Build a Marketplace App?

The short answer: Discoverability.

A few years ago, I built a fitness tracking app for a niche sport. It was a hobby project to better track my BJJ training.  Since then, I continue to average ~10 registrations weekly without any marketing efforts.

Consistent BJJ Tracker sign-ups are driven from Google Play. Even though it is only a web app (PWA), I was able to bundle it into an APK file using Trusted Web Activities and Digital Asset Links. Having an app listed in a marketplace leads to new users finding it naturally.

My next side project was a SAAS for split testing & conversion optimization. It helps websites A/B test to figure out what front-end changes lead to more sales, sign-ups, etc. The Shopify App Store was as perfect fit to attract shop owners to use SplitWit. I decided to build a public, embedded, Shopify app to reach new prospects.

I’ll explain how I did it, along with examples of building another one, all using PHP. This guide will make launching a Shopify App Store app easy, fast, repeatable.

SplitWit on Shopify

Creating a Public Shopify App with PHP

Embedded Shopify apps display in a merchant’s admin dashboard. They are meant to “add functionality to Shopify stores“. They are hosted on the developer’s infrastructure and are loaded via iFrame within Shopify. You can create a new app in your Shopify Partners dashboard to get started.

create a shopify app

Since the SplitWit SAAS already existed as a subscription web app built on the LAMP stack, I only had to handle Shopify specific authorization and payments. I could essentially load the existing app in the dashboard’s iFrame after authentication. The new code I wrote contains methods for checking installation status, building the oAuth URL, subscribing users to recurring application charges, and more.

When I created my next Shopify app, Click to Call, I leveraged that code and refactored it to be more reusable. Configurable parameters let me set the database and API credentials dynamically.

Step 1: Check Installation Status

When the app’s url loads in the merchant admin dashboard, the first step is to check installation status for that shop.

public function checkInstallationStatus(){
	$conn = $this->conn;
	$shop = $_GET['shop'];

	//check if app is already installed or not
	$statement = $conn->prepare("SELECT * FROM `shopify_installation_complete` WHERE shop = :shop");
	$statement->execute(['shop' => $shop]);
	$count = $statement->rowCount();
	if($count == 0){
		//app is not yet installed
		return false;
	}else{
		//app is already installed
		$row = $statement->fetch();
		return $row;
	}

}

You’ll notice we don’t hit any Shopify API for this. Instead, our own database is queried. We manually track if the app has already been installed in a MySql table.

shopify installation record in a mysql database table

Two database tables are used to manage the Shopify App installation:

CREATE TABLE IF NOT EXISTS `shopify_authorization_redirect` (
    `shopify_authorization_redirect_id` int NOT NULL AUTO_INCREMENT,
    `shop` varchar(200),
    `nonce` varchar(500),
    `scopes` varchar(500),
    created_date datetime DEFAULT CURRENT_TIMESTAMP,
    updated_date datetime ON UPDATE CURRENT_TIMESTAMP,
    PRIMARY KEY (`shopify_authorization_redirect_id`)
);

 
CREATE TABLE IF NOT EXISTS `shopify_installation_complete` (
    `shopify_installation_complete_id` int NOT NULL AUTO_INCREMENT,
    `splitwit_account_id` int,
    `splitwit_project_id` int,
    `shop` varchar(200),
    `access_token` varchar(200),
    `scope` varchar(200),
    `expires_in` int,
    `associated_user_scope` varchar(200),
    `associated_user_id` BIGINT,
    `associated_user_first_name` varchar(200),
    `associated_user_last_name` varchar(200),
    `associated_user_email` varchar(200),
    `associated_user_email_verified` varchar(10),
    `associated_user_account_owner` varchar(10),
    `associated_user_account_locale` varchar(10),
    `associated_user_account_collaborator` varchar(10),
    created_date datetime DEFAULT CURRENT_TIMESTAMP,
    updated_date datetime ON UPDATE CURRENT_TIMESTAMP,
    PRIMARY KEY (`shopify_installation_complete_id`)
);

The root file (index.php) looks like this:

<?php

require '/var/www/html/service-layer/shopify-app-service.php';
include 'shopify-creds.php'; // $api_key, $secret, $app_db, $app_slug
use SplitWit\ShopifyService\ShopifyService;
$shopify_service = new ShopifyService($api_key, $secret, $app_db);

$already_installed = $shopify_service->checkInstallationStatus();

if(!$already_installed){
    $install_redirect_url = $shopify_service->buildAuthorizationUrl(false, $app_slug);
}else{
    $install_redirect_url = $shopify_service->buildAuthorizationUrl(true, $app_slug);
}
header('Location: ' . $install_redirect_url );

?>

After determining the merchant’s installation status, the next step is to authenticate them.

oAuth Authentication

The Shopify developer resources explain “how to ask for permission” with oAuth. The merchant user needs to be redirected to a Shopify URL:

https://{shop}.myshopify.com/admin/oauth/authorize?client_id={api_key}&scope={scopes}&redirect_uri={redirect_uri}&state={nonce}&grant_options[]={access_mode}

I wrote a PHP class “ShopifyService” (shopify-app-service.php) to handle all of the Shopify specific logic. The method buildAuthorizationUrl() builds the Shopify authorization URL. It accepts a boolean parameter set according to the merchant’s installation status. That value toggles the authorization URL’s redirect URI, directing the code flow through either first-time installation or re-authentication.

The built URL includes query params: an API key, a nonce, the scope of permission being requested, and a redirect URI. The shop name is the subdomain, and can be pulled as GET data delivered to your app.

The API key can be found in the developer’s partner dashboard in the app’s overview page.

A nonce (“number used once”) is used as an oAuth state parameter. It serves to “link requests and callbacks to prevent cross-site request forgery attacks.” We save that random value in our database to check against during the oAuth callback.

The redirect URI (the oAuth callback) is dynamic based on the users installation status.

public function buildAuthorizationUrl($reauth = false, $slug= "shopify-app"){
	$conn = $this->conn;
	$requestData = $this->requestData;
	$scopes = "write_script_tags"; //write_orders,read_customers, read_content
	$nonce = bin2hex(random_bytes(10));
	$shop = $requestData['shop'];

	//first check if there is already a record for this shop. If there is, delete it first.
	$statement = $conn->prepare("SELECT * FROM `shopify_authorization_redirect` WHERE shop = :shop");
	$statement->execute(['shop' => $shop]);
	$count = $statement->rowCount();
	
	if($count > 0){
		$statement = $conn->prepare("DELETE FROM `shopify_authorization_redirect` WHERE shop = :shop");
		$statement->execute(['shop' => $shop]);
	}

	$statement = $conn->prepare("INSERT INTO `shopify_authorization_redirect` (shop, nonce, scopes) VALUES (:shop, :nonce, :scopes)");
	$statement->bindParam(':shop', $shop);
	$statement->bindParam(':nonce', $nonce);
	$statement->bindParam(':scopes', $scopes);
	$statement->execute();

	
	$redirect_uri = "https://www.splitwit.com/".$slug."/authorize-application";
	
	if($reauth){ //change the redirect URI
		$redirect_uri = "https://www.splitwit.com/".$slug."/reauthorize-application";
	}

	$redirect_url = "https://".$shop."/admin/oauth/authorize?client_id=". $this->api_key ."&scope=".$scopes."&redirect_uri=". $redirect_uri ."&state=".$nonce . "&grant_options[]=per-user";

	return $redirect_url;

}

Both possible redirect URLs needed to be white-listed in the “App setup” page.

white listed URLs

A location header routes the user. If the app hasn’t been installed yet, Shopify prompts the merchant to confirm authorization.

install shopify app

If the app was already installed then the oAuth grant screen is skipped entirely and the merchant is immediately routed to the /reauthorize-application resource instead (and ultimately lands on the app home screen).

Install App & Register the Merchant User

What actually happens when “Install app” is clicked?  The user is redirected from Shopify permissions screen back to our app ( /authorize-application ), calling the authorizeApplication() function. That method receives four values as GET parameters: ‘shop’, ‘state’, ‘hmac’, ‘code’

The ‘shop’ name is used to look up the nonce value we saved when the Shopify authorization URL was first built. We compare it to the ‘state’ parameter. This security step ensures that the callback request is valid and is not fraudulent. We also check that the shop name provided matches a valid Shopify hostname. Here is the relevant code, pulled from authorizeApplication():

$conn = $this->conn; 
$requestData = $this->requestData;
$requiredKeys = ['code', 'hmac', 'state', 'shop'];
foreach ($requiredKeys as $required) {
    if (!in_array($required, array_keys($requestData))) {
        throw new Exception("The provided request data is missing one of the following keys: " . implode(', ', $requiredKeys));
    }
}

//lookup and validate nonce
$shop = $requestData['shop'];

$statement = $conn->prepare("SELECT * FROM `shopify_authorization_redirect` WHERE shop = :shop");
$statement->execute(['shop' => $shop]);
$count = $statement->rowCount();
if($count == 0){
    throw new Exception("Nonce not found for this shop.");
}
$row = $statement->fetch();
$nonce = $row['nonce'];
//

//make sure the 'state' parameter provided matches the stored nonce
$state = $requestData['state'];
if($state !== $nonce){
    throw new Exception("Nonce does not match provided state.");
}
//

//validate the shop name
$pattern = "/[a-zA-Z0-9][a-zA-Z0-9\-]*\.myshopify\.com[\/]?/";
if(!preg_match($pattern, $shop)) {
    throw new Exception("The shop name is an invalid Shopify hostname.");
}

Every request or redirect from Shopify” includes a HMAC value that can be used to verify its authenticity. Here is how I do it in PHP:

public function verifyHmac($requestData){
	// verify HMAC signature. 
	// https://help.shopify.com/api/getting-started/authentication/oauth#verification
	if( !isset($requestData['hmac'])){
		return false;
	}

	$hmacSource = [];

	foreach ($requestData as $key => $value) {
	    
	    if ($key === 'hmac') { continue; }

	    // Replace the characters as specified by Shopify in the keys and values
	    $valuePatterns = [
	        '&' => '%26',
	        '%' => '%25',
	    ];
	    $keyPatterns = array_merge($valuePatterns, ['=' => '%3D']);
	    $key = str_replace(array_keys($keyPatterns), array_values($keyPatterns), $key);
	    $value = str_replace(array_keys($valuePatterns), array_values($valuePatterns), $value);

	    $hmacSource[] = $key . '=' . $value;
	}

	sort($hmacSource);
	$hmacBase = implode('&', $hmacSource);
	$hmacString = hash_hmac('sha256', $hmacBase, $this->secret);
	// Verify that the signatures match
    if ($hmacString !== $requestData['hmac']) {
        return false;
    }else{
    	return true;
    }
}

That method is called in the class construct function, to be sure it happens every time.

The ‘code’ parameter is the access code. It is exchanged for an access token by sending a request to the shop’s access_token endpoint. We record that token to the ‘shopify_installation_complete’ table along with relevant data.

To fully complete the installation, app specific project records are saved. For SplitWit, this means a user-account is created along with an initial project. Any JavaScript tags are injected onto the merchant’s site using the Shopify admin API ScriptTag resource. Linking a privately hosted JS file, unique to each merchant, allows our app to dynamically update the shop website. You can learn about how that snippet tag works in another post that explains how the visual editor is built.

Lastly, a webhook is created to listen for when this app in uninstalled ( ‘topic’ => ‘app/uninstalled’ ) in order to call our “uninstallApplication” method. Webhooks allow you to listen for certain events in a shop, and run code based on data about what happened.

Once installation is complete, our server returns a header that reloads the app.

shopify app

Below is the original authorizeApplication() method. Eventually, I moved app specific logic into its own files after refactoring this class to support another SAAS, Click to Call.

public function authorizeApplication(){
	$conn = $this->conn; 
	$requestData = $this->requestData;
	$requiredKeys = ['code', 'hmac', 'state', 'shop'];
        foreach ($requiredKeys as $required) {
           if (!in_array($required, array_keys($requestData))) {
             throw new Exception("The provided request data is missing one of the following keys: " . implode(', ', $requiredKeys));
           }
        }

	//lookup and validate nonce
	$shop = $requestData['shop'];
	
	$statement = $conn->prepare("SELECT * FROM `shopify_authorization_redirect` WHERE shop = :shop");
	$statement->execute(['shop' => $shop]);
	$count = $statement->rowCount();
	if($count == 0){
        throw new Exception("Nonce not found for this shop.");
	}
	$row = $statement->fetch();
	$nonce = $row['nonce'];
	//
	
	//make sure the 'state' parameter provided matches the stored nonce
	$state = $requestData['state'];
	if($state !== $nonce){
        throw new Exception("Nonce does not match provided state.");
	}
	//
	
	//validate the shop name
	$pattern = "/[a-zA-Z0-9][a-zA-Z0-9\-]*\.myshopify\.com[\/]?/";
	if(!preg_match($pattern, $shop)) {
        throw new Exception("The shop name is an invalid Shopify hostname.");
	}
	//

	$already_installed = $this->checkInstallationStatus();
	//if it is already installed, then lets update the access token 
        if(!$already_installed){
    	  //install the app
    	
	  //exchange the access code for an access token by sending a request to the shop’s access_token endpoint
	  $code = $requestData['code'];
	  $post_url = "https://" . $shop . "/admin/oauth/access_token";
		
	  $params = [
            'client_id'    => $this->api_key,
            'client_secret'    => $this->secret,
            'code'    => $code
          ];

          $curl_response_json = $this->curlApiUrl($post_url, $params);
	  $access_token = $curl_response_json['access_token'];
		
          $statement = $conn->prepare("INSERT INTO `shopify_installation_complete` (shop, access_token, scope, expires_in, associated_user_scope, associated_user_id, associated_user_first_name, associated_user_last_name, associated_user_email, associated_user_email_verified, associated_user_account_owner, associated_user_account_locale, associated_user_account_collaborator) VALUES (:shop, :access_token, :scope, :expires_in, :associated_user_scope, :associated_user_id, :associated_user_first_name, :associated_user_last_name, :associated_user_email, :associated_user_email_verified, :associated_user_account_owner, :associated_user_account_locale, :associated_user_account_collaborator)");
		
	  $statement->bindParam(':shop', $shop);
		
	  $statement->bindParam(':access_token', $access_token);
	  $statement->bindParam(':scope', $curl_response_json['scope']);
	  $statement->bindParam(':expires_in', $curl_response_json['expires_in']);
	  $statement->bindParam(':associated_user_scope', $curl_response_json['associated_user_scope']);
	  $statement->bindParam(':associated_user_id', $curl_response_json['associated_user']['id']);
	  $statement->bindParam(':associated_user_first_name', $curl_response_json['associated_user']['first_name']);
	  $statement->bindParam(':associated_user_last_name', $curl_response_json['associated_user']['last_name']);
	  $statement->bindParam(':associated_user_email', $curl_response_json['associated_user']['email']);
	  $statement->bindParam(':associated_user_email_verified', $curl_response_json['associated_user']['email_verified']);
	  $statement->bindParam(':associated_user_account_owner', $curl_response_json['associated_user']['account_owner']);
	  $statement->bindParam(':associated_user_account_locale', $curl_response_json['associated_user']['locale']);
	  $statement->bindParam(':associated_user_account_collaborator', $curl_response_json['associated_user']['collaborator']);

	  $statement->execute();
	  $installation_complete_id = $conn->lastInsertId();
		 
	  if(isset($curl_response_json['associated_user']['email']) && strlen($curl_response_json['associated_user']['email']) > 0){

		$store_name = explode(".", $shop);
		$store_name = ucfirst($store_name[0]);

		//create account
		$method = "thirdPartyAuth";
		$user_service_url = "https://www.splitwit.com/service-layer/user-service.php?third_party_source=shopify&method=" . $method . "&email=".$curl_response_json['associated_user']['email']."&companyname=" .$store_name . "&first=" . $curl_response_json['associated_user']['first_name'] . "&last=" . $curl_response_json['associated_user']['last_name'] ;
			
		$params = [];

		$curl_user_response_json = $this->curlApiUrl($user_service_url, $params);
		
		$account_id = $curl_user_response_json['userid']; 
			
		$method = "createProject";
			
		$project_service_url = "https://www.splitwit.com/service-layer/project-service.php?method=" . $method . "&accountid=" . $account_id;

		$params = [
	            'projectname'    => $store_name . " Shopify",
	            'projectdomain'    => "https://".$shop,
	            'projectdescription'    => ""
	        ];

		$curl_project_response_json = $this->curlApiUrl($project_service_url, $params);
		$project_id = $curl_project_response_json['projectid'];
		$snippet = $curl_project_response_json['snippet'];
			
			

		//inject JS snippet into site
		// https://shopify.dev/docs/admin-api/rest/reference/online-store/scripttag#create-2020-04
		$create_script_tag_url = "https://" . $this->api_key . ":" . $this->secret . "@" . $shop . "/admin/api/2020-04/script_tags.json";
		$params = [
                    'script_tag' => [
                     'event' => 'onload',
                     'src' => 'https://www.splitwit.com/snippet/' . $snippet
                    ]
        	];

        	$headers = array(
		  'X-Shopify-Access-Token:' . $access_token,
		  'content-type: application/json'
		);

		$json_string_params = json_encode($params);

		$create_script_curl_response_json = $this->curlApiUrl($create_script_tag_url, $json_string_params, $headers);
		
		//shopify app should only ever have access to this one project.
		//write accountID and ProjectID to this shopify_installation_complete record.

		$statement = $conn->prepare("UPDATE `shopify_installation_complete` SET splitwit_account_id = ?, splitwit_project_id = ? WHERE shopify_installation_complete_id = ?");

		$statement->execute(array($account_id, $project_id, $installation_complete_id));
			
    	}
		
    	//create webhook to listen for when app in uninstalled.
	//https://{username}:{password}@{shop}.myshopify.com/admin/api/{api-version}/{resource}.json
	// https://shopify.dev/docs/admin-api/rest/reference/events/webhook#create-2020-04
	$create_webhook_url = "https://" . $this->api_key . ":" . $this->secret . "@" . $shop . "/admin/api/2020-04/webhooks.json";
	$params = [
                'webhook' => [
                    'topic' => 'app/uninstalled',
                    'address' => 'https://www.splitwit.com/service-layer/shopify-app-service?method=uninstallApplication',
                    'format' => 'json'
                ]
        ];

	$headers = array(
		'X-Shopify-Access-Token:' . $access_token,
		'content-type: application/json'
	);
		
	$json_string_params = json_encode($params);

    	$create_webhook_curl_response_json = $this->curlApiUrl($create_webhook_url, $json_string_params, $headers);
		
	//installation complete.
   }

   header('Location: ' . "https://" . $shop . "/admin/apps/splitwit");
	
}

You’ll notice that I call a custom method that abstracts the PHP cURL (client URL library) methods. This helps me avoid repeating the same code in multiple places.

public function curlApiUrl($url, $params, $headers = false, $use_post = true, $use_delete = false, $use_put = false){
		
	$curl_connection = curl_init();
	// curl_setopt($curl_connection, CURLOPT_FOLLOWLOCATION, true);
	if($headers){
	    curl_setopt($curl_connection, CURLOPT_HTTPHEADER, $headers);
	    curl_setopt($curl_connection, CURLOPT_HEADER, false);
	}
	curl_setopt($curl_connection, CURLOPT_URL, $url);
    
       // TODO: refactor these three conditions into one, that accepts the RESTful request type!!
       if($use_post){
	    curl_setopt($curl_connection, CURLOPT_POST, true);
	    curl_setopt($curl_connection, CURLOPT_POSTFIELDS, $params);
	}
        if($use_delete){
	    curl_setopt($curl_connection, CURLOPT_CUSTOMREQUEST, "DELETE");
	}
        if($use_put){
	    curl_setopt($curl_connection, CURLOPT_CUSTOMREQUEST, "PUT");
	    curl_setopt($curl_connection, CURLOPT_POSTFIELDS, $params);
	}
	//end TODO

	curl_setopt($curl_connection, CURLOPT_RETURNTRANSFER, true);
	$curl_response = curl_exec($curl_connection);
	$curl_response_json = json_decode($curl_response,true);
	curl_close($curl_connection);
	return $curl_response_json;
}

The merchant will be able to find the app in the ‘Apps’ section of their dashboard. Shopify remembers that permission was granted by the merchant.

installed apps dashboard

Returning User Log in

The oAuth grant screen will not show again when the app is selected in the future.  As the installation status returns true, our code will flow into the reAuthenticate() method. The same validation checks are performed and a new access token is received.

   
public function reAuthenticate(){
    $conn = $this->conn; 
    $requestData = $this->requestData;
    $requiredKeys = ['code', 'hmac', 'state', 'shop'];
    foreach ($requiredKeys as $required) {
        if (!in_array($required, array_keys($requestData))) {
            throw new Exception("The provided request data is missing one of the following keys: " . implode(', ', $requiredKeys));
            // return;
        }
    }

    //lookup and validate nonce
    $shop = $requestData['shop'];
    
    $statement = $conn->prepare("SELECT * FROM `shopify_authorization_redirect` WHERE shop = :shop");
    $statement->execute(['shop' => $shop]);
    $count = $statement->rowCount();
    if($count == 0){
        throw new Exception("Nonce not found for this shop.");
    }
    $row = $statement->fetch();
    $nonce = $row['nonce'];
    //
    
    //make sure the 'state' parameter provided matches the stored nonce
    $state = $requestData['state'];
    if($state !== $nonce){
        throw new Exception("Nonce does not match provided state.");
    }
    //
    
    //validate the shop name
    $pattern = "/[a-zA-Z0-9][a-zA-Z0-9\-]*\.myshopify\.com[\/]?/";
    if(!preg_match($pattern, $shop)) {
        throw new Exception("The shop name is an invalid Shopify hostname.");
    }

    //exchange the access code for an access token by sending a request to the shop’s access_token endpoint
    $code = $requestData['code'];
    $post_url = "https://" . $shop . "/admin/oauth/access_token";
    
    $params = [
        'client_id'    => $this->api_key,
        'client_secret'    => $this->secret,
        'code'    => $code
    ];

    $curl_response_json = $this->curlApiUrl($post_url, $params);
    $access_token = $curl_response_json['access_token'];
    
    $statement = $conn->prepare("UPDATE `shopify_installation_complete` SET access_token = ? WHERE shop = ?");
    $statement->execute(array($access_token, $shop));

    header('Location: ' . "/home?shop=".$shop);
}

The merchant is routed to the app’s /home location. A few session variables are set and the user interface is loaded.

<?php
require '/var/www/html/service-layer/shopify-app-service.php';
use SplitWit\ShopifyService\ShopifyService;
$shopify_service = new ShopifyService();
include '/var/www/html/head.php'; 
?>
<style>
	.back-to-projects{
		display: none;
	}   
</style>

<body class="dashboard-body">
    <?php 
    // log the user out...
    $sess_service = new UserService();
    $sess_service -> logout();
    //logout destroys the session. make sure to start a new one.
    if (session_status() == PHP_SESSION_NONE) {
        session_start();
    }
    // ...then log them in
    $already_installed = $shopify_service->checkInstallationStatus();
    $shopify_service->makeSureRecordsExist($already_installed);
    $projectid = $shopify_service->splitwit_project_id; 
    $accountid = $shopify_service->splitwit_account_id; 
    $_SESSION['accountid'] = $accountid;
    $_SESSION['userid'] =  $accountid;
    $_SESSION['email'] = $already_installed['associated_user_email'];
    
    $sess_service -> login();
    $_SESSION['active'] = true;
    include '/var/www/html/includes/experiments-ui.php'; 
    
    ?>
</body>
</html>

The method makeSureRecordsExist() checks that the SplitWit user account and project records exist, as a failsafe. The .back-to-projects CTA is hidden because Shopify users only have access to one project for their shop. The app is installed for free, while premium functionality requires a subscription after a one-week trial.

free trial UI in shopify

When building my second Shopify app, I started with an empty home screen UI:

<?php
require '/var/www/html/service-layer/shopify-app-service.php';
include 'shopify-creds.php';
use SplitWit\ShopifyService\ShopifyService;
$shopify_service = new ShopifyService($api_key, $secret, $app_db);
?>
<html>
<head>
</head>
<body>
   
</body>
<script>


    if(self!==top){
        // if loaded outside of an iframe, redirect away to a marketing page
        window.location = "https://www.splitwit.com";
    }


</script>
</html>

Subscription Payment

SplitWit’s codebase is originally used as a non-Shopify, stand-alone, web app SAAS. It uses Stripe as a payment gateway. Shopify requires apps to use their Billing API instead. To remedy this, I’m able to write Shopify specific front-end code with a simple JavaScript check. I leverage the browser’s window.self property to check if my app’s code is running in the top most window (opposed to being nested in an iFrame).

if(self!==top){
	// shopify app
	$(".activate-cta").remove();
	if(window.pastDueStatus || window.customerId.length === 0){
		$(".activate-loading").show();

		$.ajax({
			url:"/service-layer/shopify-app-service?method=createRecurringApplicationCharge",
			complete: function(response){
				console.log(response)
				//user is redirected to shopify confirmation screen
				$(".activate-loading").hide();
				$(".activate-cta-top").attr("href", response.responseText).show();
			}
		});
	}
	 
	$(".back-cta").click(function(){
		window.history.back();
	})
	$(".reset-pw-cta").hide()

}else{

	$(".activate-cta").click(function(){
		$(".stripe-payment-modal").show();
	});
	
	$(".back-cta").hide();
}

If it’s not the top most window, I assume the code is running in Shopify. I’ll change the click-event listener on the .activate-cta element to create a recurring subscription charge. An AJAX call is made to our PHP end-point that hits Shopify’s RecurringApplicationCharge API.

public function createRecurringApplicationCharge(){
	
	$conn = $this->conn;
	$statement = $conn->prepare("SELECT * FROM `shopify_installation_complete` WHERE splitwit_account_id = :splitwit_account_id");
	$statement->execute(['splitwit_account_id' => $_SESSION['accountid']]);
	$row = $statement->fetch();
	$shop = $row['shop'];
	$access_token = $row['access_token'];
	
	$create_recurring_charge_url = "https://" . $this->api_key . ":" . $this->secret . "@" . $shop . "/admin/api/2020-04/recurring_application_charges.json";
	$params = [
        'recurring_application_charge' => [
            'name' => 'Basic Plan',
            'price' => 25.0,
            // 'return_url' => "https://" . $shop . "/admin/apps/splitwit",
            // 'test' => true,
            'return_url' => "https://www.splitwit.com/service-layer/shopify-app-service?method=confirmSubscription"
        ]
	];
	$headers = array(
		'X-Shopify-Access-Token: ' . $access_token,
	 	'content-type: application/json'
	);
	$json_string_params = json_encode($params);

	$create_recurring_charge_curl_response_json = $this->curlApiUrl($create_recurring_charge_url, $json_string_params, $headers);
	echo $create_recurring_charge_curl_response_json['recurring_application_charge']['confirmation_url'];
}

The charge ID (delivered by the Shopify request to our ‘return_url’), payment processor, and subscription expiry date are saved to our database on call-back before returning a location header to reload the app.

public function confirmSubscription(){
	
	$conn = $this->conn;
	$statement = $conn->prepare("SELECT * FROM `shopify_installation_complete` WHERE splitwit_account_id = :splitwit_account_id");
	$statement->execute(['splitwit_account_id' => $_SESSION['accountid']]);
	$row = $statement->fetch();
	$shop = $row['shop'];
 
 	$charge_id = $_REQUEST['charge_id'];
	//write shopify billing ID to db
	$sql = "UPDATE `account` SET payment_processor = ?, billing_customer_id = ?, current_period_end = ?, past_due = 0 WHERE accountid = ?"; 
	$result = $conn->prepare($sql); 
	$current_period_end = new \DateTime();  //we need the slash here (before DateTime class name), since we're in a different namespace (declared at the top of this file)
	$current_period_end->modify( '+32 day' );
	$current_period_end = $current_period_end->format('Y-m-d H:i:s'); 
	$payment_processor = "shopify";
	$result->execute(array($payment_processor, $charge_id, $current_period_end, $_SESSION['accountid']));
	
	//redirect to app
	header('Location: ' . "https://" . $shop . "/admin/apps/splitwit");

}

That charge ID (saved to our database in a column titled “billing_customer_id”) can later be passed back to Shopify to delete the recurring charge.

Cancel a Subscription

Once a subscription is active, I can check  the payment processor saved the the account’s DB record to toggle the “cancel account” functionality from Stripe to Shopify.

<?php if ($account_row['payment_processor'] == "shopify"){ ?>
	//hit shopify service

	$(".cancel-cta").click(function(){
		//
		$.ajax({
			url:"/service-layer/shopify-app-service?method=cancelSubscription",
			complete: function(response){
				window.location.reload();
			}
		});
	});

<?php }else{ ?>
	//hit the stripe service
	
	$(".cancel-cta").click(function(){
		$(".cancel-subscription-modal").show();
	});

<?php }?>

The cancelSubscription method hits the same Shopify recurring_application_charges API, but uses a DELETE request. It also deletes the Shopify billing ID from our records.

public function cancelSubscription(){
	
	$conn = $this->conn;
	$statement = $conn->prepare("SELECT * FROM `shopify_installation_complete` WHERE splitwit_account_id = :splitwit_account_id");
	$statement->execute(['splitwit_account_id' => $_SESSION['accountid']]);
	$row = $statement->fetch();
	$shop = $row['shop'];
	$access_token = $row['access_token'];

	$statement = $conn->prepare("SELECT * FROM `account` WHERE accountid = :accountid");
	$statement->execute(['accountid' => $_SESSION['accountid']]);
	$account_row = $statement->fetch();
	$charge_id = $account_row['billing_customer_id'];


	$delete_recurring_charge_url = "https://" . $this->api_key . ":" . $this->secret . "@" . $shop . "/admin/api/2020-04/recurring_application_charges/#" . $charge_id . ".json";

	$params = [];
	$headers = array(
		'X-Shopify-Access-Token: ' . $access_token,
	 	'content-type: application/json'
	);
	$json_string_params = json_encode($params);
	$delete = true;

	$delete_recurring_charge_curl_response_json = $this->curlApiUrl($delete_recurring_charge_url, $json_string_params, $headers, $delete);

	//delete shopify billing ID from db
	$empty_string = "";
	$sql = "UPDATE `account` SET payment_processor = ?, billing_customer_id = ? WHERE accountid = ?"; 
	$result = $conn->prepare($sql); 
	$result->execute(array($empty_string, $empty_string, $_SESSION['accountid']));
	
	echo $delete_recurring_charge_curl_response_json;


}

I can use these same recurring application API end-point functions with minimal adjustments for other Shopify apps that I build. After refactoring, I am able to specify an app database as a GET parameter in the AJAX calls to my Shopify PHP service.

Uninstall the App

delete shopify app

Merchants can choose to delete apps from their shop. This will remove it from their list of installed apps. If they try installing it again, they will be re-promoted for permissions. When an app is deleted, a webhook is notified so that code can handle server-side uninstall logic:

The payment processor and billing ID associated with the merchant’s account is set to an empty string. The ‘shopify_installation_complete’ shop record is deleted.

public function uninstallApplication(){
	$conn = $this->conn; 
	
	$res = '';
	$hmac_header = $_SERVER['HTTP_X_SHOPIFY_HMAC_SHA256'];
	$topic_header = $_SERVER['HTTP_X_SHOPIFY_TOPIC'];
	$shop_header = $_SERVER['HTTP_X_SHOPIFY_SHOP_DOMAIN'];
	$data = file_get_contents('php://input'); //similar to $_POST
	$decoded_data = json_decode($data, true);
	$verified = $this->verifyWebhook($data, $hmac_header);

	if( $verified == true ) {
	  if( $topic_header == 'app/uninstalled' || $topic_header == 'shop/update') {
	    if( $topic_header == 'app/uninstalled' ) {
			$domain = $decoded_data['domain'];

			$statement1 = $conn->prepare("SELECT * FROM `shopify_installation_complete` WHERE shop = ?");
			$statement1->execute(array($domain));
			$row = $statement1->fetch();
			$accountid = $row['splitwit_account_id'];

			//delete shopify billing ID from db
			$empty_string = "";
			$result = $conn->prepare("UPDATE `account` SET payment_processor = ?, billing_customer_id = ? WHERE accountid = ?"); 
			$result->execute(array($empty_string, $empty_string, $accountid));

			$statement = $conn->prepare("DELETE FROM `shopify_installation_complete` WHERE shop = ?");
			$statement->execute(array($domain));

	    } else {
	      $res = $data;
	    }
	  }
	} else {
	  $res = 'The request is not from Shopify';
	}

}

Any webhook requests have the HMAC delivered as a header (instead of a query param, as in the case of oAuth requests) and is processed differently. “The HMAC verification procedure for OAuth is different from the procedure for verifying webhooks“. The method verifyWebhook() takes care of it:

public function verifyWebhook($data, $hmac_header){
  $calculated_hmac = base64_encode(hash_hmac('sha256', $data, $this->secret, true));
  return hash_equals($hmac_header, $calculated_hmac);
}

Cache Busting

When project changes are recorded in the app, the merchant’s snippet file is updated. We need to be sure that their website recognizes the latest version. In a separate class (that handles project & snippet logic) I make a HTTP request to my method that re-writes the script tag.

public function updateSnippetScriptTag(){
	$projectid = $_GET['projectid'];
	$conn = $this->conn;
	$sql = "SELECT * FROM `shopify_installation_complete` WHERE splitwit_project_id = ?"; 
	$result = $conn->prepare($sql); 
	$result->execute(array($projectid));
	$row = $result->fetch(\PDO::FETCH_ASSOC);
	$number_of_rows = $result->rowCount();
	if($number_of_rows == 1){
		$access_token = $row['access_token'];
		$shop = $row['shop'];
		$sql = "SELECT * FROM `project` WHERE projectid = ?"; 
		$project_result = $conn->prepare($sql); 
		$project_result->execute(array($projectid));
		$project_row = $project_result->fetch(\PDO::FETCH_ASSOC);
		$snippet = $project_row['snippet'];			

		$script_tag_url = "https://" . $this->api_key . ":" . $this->secret . "@" . $shop . "/admin/api/2020-04/script_tags.json";
		$headers = array(
		  'X-Shopify-Access-Token:' . $access_token,
		  'content-type: application/json'
		);
		$params = [];
		$json_string_params = json_encode($params);
		$use_post = false;
		//get existing script tag
		$get_script_curl_response_json = $this->curlApiUrl($script_tag_url, $json_string_params, $headers, $use_post);
		$tags = $get_script_curl_response_json['script_tags'];
	
		foreach ($tags as $tag) {
			$id = $tag['id'];
			$delete_script_tag_url = "https://" . $this->api_key . ":" . $this->secret . "@" . $shop . "/admin/api/2020-04/script_tags/" . $id . ".json";
			$use_delete = true;
			$delete_script_curl_response_json = $this->curlApiUrl($delete_script_tag_url, $json_string_params, $headers, $use_post, $use_delete);
		}
		 
		//add snippet
		$snippet = "https://www.splitwit.com/snippet/" . $snippet . "?t=" . time();
		$params = [
			'script_tag' => [
				'event' => 'onload',
				'src' => $snippet 
			]
		];
		$json_string_params = json_encode($params);
		$create_script_curl_response_json = $this->curlApiUrl($script_tag_url, $json_string_params, $headers);	 

	}
}

Once our Shopify app is built and tested we can begin to prepare for submission to the Shopify App Market.

Preparing for production

Shopify allows you to test your app on a development store.

test your app

After debugging your code locally, make sure it works end-to-end in Shopify’s environment.

test your app on Shopify

Even though the app is “unlisted”, and has not yet been accepted into the Shopify App Market, you’ll still be able to work through the entire UX flow.

install an unlisted app

GDPR mandatory webhooks

Each app developer is responsible for making sure that the apps they build for the Shopify platform are GDPR compliant.” Every app is required to provide three webhook end-points to help manage the data it collects. These end-points make requests to to view stored customer data, delete customer data, and delete shop data.  After handling the request, an HTTP status of 200/OK should be returned. PHP lets us do that with its header() function:

header("HTTP/1.1 200 OK");

These GDPR webhook subscriptions can be managed on the “App setup” page.

gdpr webhook settings

App Listing

Before submitting your app to the Shopify App Market, you’ll need to complete “Listing Information”. This section includes the app’s name, icon, description, pricing details, and more. It is encouraged to include screenshots and a demonstration video. Detailed app review instructions, along with screenshots and any on-boarding information, will help move the approval process along more quickly.

app review instructions in the app listing section of Shopify

Approval Process

Complete the setup and listing sections, and submit your app.

shopify app listing issues

You’ll receive an email letting you know that testing will begin shortly.

email from shopify

You may be required to make updates based on feedback from Shopify’s review process. After making any required changes, your application will be listed on the Shopify App Store. Below is an example of feedback that I had received:

Required changes from Shopify's app review process

To remedy the first required change I added additional onboarding copy to the app’s listing and included a demonstration YouTube video.

The second point was fixed by stopping any links from opening in new tabs. (Although, the reviewer’s note about ad blocking software stopping new tabs from opening is bogus).

The third issue was resolved by making sure the graphic assets detailed in my app listing were consistent.

Soon after making these changes, my app was finally approved and listed.

Keep Building

While writing this article I extended and refactored my PHP code to support multiple apps. I added configuration files to keep database settings modular. The Shopify PHP class can serve as back-end to several implementations. If you have any questions about how to build a Shopify app, or need my help, send me a message.

Update:

I wrote a subsequent post about building another Shopify app. It’s called SplitWit Click to Call. It explains the creative details that go into shipping a fulling working SAAS. I dive into new features that are only available to Shopify themes running the latest OS2.0 experience.

Custom UI notifications

UI feedback alerts

Showing brief notifications to website visitors is an important UI/UX component. They’re useful for providing feedback. They can communicate success, failure, or warnings.

Don Norman (The Design of Everyday Things) mentions that “Feedback is essential, but not when it gets in the way of other things, including a calm and relaxing environment” and goes on to say “Feedback is essential, but it has to be done correctly”.

A common use-case is data validation. Specifically, when logging in or signing up. If the user enters an invalid email address, or wrong login credentials, we need to let them know. The built in browser alert() is clunky and unsophisticated. Plugins are bloated and over-engineered. I wrote some basic HTML, CSS, and JavaScript that gets the job done and looks great.

My code provides two versions of the alert. The first is a basic sticky bar that fades in and out at the top of the page.

example of alert message for an invalid email address

The other flashes in the middle of the screen. I call it “in-your-face” alerts and reserve them for positive success messages.

example of a flashing UI alert to provide positive feedback to users

The CSS adds styles for both versions. Both utilize ‘position: fixed’ to stay in a set location on the page. The “in-your-face” example uses a pulse animation to achieve its effect.

<!-- UI-notifications.css -->
<style>
body{
  margin: 0px;
}
.status-message{
  display: none;
  color: white;
  text-align: center;
  font-size: 16px;
  padding: 8px;
  border-top: 1px solid white;
  border-bottom: 1px solid white;
  position: fixed;
  width: 100%;
  top: 0px;
  padding: 28px 8px;
  background-color: #b12650;
  z-index: 1000;
}
.status-message-inner{
  margin: 0px;
}

.status-message-close{
  cursor: pointer;
  position: fixed;
  right: 10px;
}
.in-your-face{
  display: none;
  position: fixed;
  top: 45%;
  width: 100%;
  text-align: center;
  font-size: 48px;
  color: white;
  z-index: 2;
}
.in-your-face-inner{
    background: #005b96;
    width: 80%;
    margin: 0 auto;
    opacity: .85;
    padding: 10px;
}
@keyframes pulse{
  50%  {transform: scale(1.2);}

}
.pulse{
  animation: pulse 0.5s ease-in infinite;
}
</style>
<!-- end UI-notifications.css -->

The javascript relies on jQuery as a dependency. It is written as a class, with a constructor and two methods. Each method takes message text as a parameter.

class UINotifications {
	constructor() {
		window.jQuery || document.write('<script src="js/vendor/jquery-1.11.2.min.js"><\/script>');
		var statusMessageHtml = '<div class="status-message"><p class="status-message-inner"><span class="status-message-text">Welcome to My App</span><span class="status-message-close">X</span></p></div>';
		var inYourFaceHtml = '<div class="in-your-face pulse"><p class="in-your-face-inner"><span class="in-your-face-text">Great Job!</span></p></div>';

		$(document).on("click", ".status-message-close", function(){
			$(".status-message").fadeOut();
		});

		this.statusMessage = $("<div/>").html(statusMessageHtml);
		this.inYourFace = $("<div/>").html(inYourFaceHtml);
		
		$('body').prepend(this.inYourFace);
		$('body').prepend(this.statusMessage);

	}

 	showStatusMessage(message){
 		var notifications = this;
	  	var message = message || "Default Message"
	  	var statusMessageTimeout;
	  	
		if(notifications.statusMessage.find(".status-message").is(':visible')){
	     clearTimeout(statusMessageTimeout);
	    }

		notifications.statusMessage.find(".status-message .status-message-text").html(message);
		notifications.statusMessage.find(".status-message").fadeIn();
		
	    statusMessageTimeout = setTimeout(function(){
	       notifications.statusMessage.find(".status-message").fadeOut(); 
	    }, 5000)
		
	}
	showInYourFace(message, callback){
		var notifications = this;
		var inYourFaceTimeout;
		var inYourFaceRandoms = ["Good work!", "Hard work!", "Nice job!", "Hustle!"]

		var message = message || inYourFaceRandoms[Math.floor(Math.random()*inYourFaceRandoms.length)];;
		var callback = callback || function(){};

		if(notifications.inYourFace.find(".in-your-face").is(':visible')){
	     clearTimeout(inYourFaceTimeout);
	    }

		notifications.inYourFace.find(".in-your-face .in-your-face-text").html(message);
		notifications.inYourFace.find(".in-your-face").show();
		
	    inYourFaceTimeout = setTimeout(function(){
	       notifications.inYourFace.find(".in-your-face").fadeOut(function(){
	       	callback();
	       }); 

	    }, 1000)
	}
}

This is a simple and lightweight solution to showing web app visitors informative alerts without using a plugin. Please, checkout the code and use it in your next project.

You can find the code on GitHub.