Build a Custom Shopify Customer Registration App (With Metafields) – Step-by-Step Guide (PHP)

In this tutorial, we’ll build a simple Shopify custom app using PHP that:

• Creates customers from a custom frontend form

• Saves additional fields (Instagram, Facebook, ENI, Website, etc.) using metafields

• Adds a wholesale tag to customers

• Uses Shopify OAuth authentication

• Works with the new Shopify customer account system

This is perfect if you want a wholesale registration form or custom onboarding system.

🚀 Step 1: Create Shopify Custom App

1. Go to your Shopify Admin

2. Navigate to:
   Settings → Apps and Sales Channels → Develop Apps

3. Create a new app

4. Configure API scopes:

read_customers
write_customers

5. Set URLs:

• App URL:

https://yourdomain.com/

• Redirect URL:

https://yourdomain.com/callback.php

🔐 Step 2: OAuth Authentication

Create a file:

📁 callback.php

<?php
include 'config.php';

if (!isset($_GET['code']) || !isset($_GET['shop'])) {
    die("Missing parameters");
}

$shop = $_GET['shop'];
$code = $_GET['code'];

$url = "https://$shop/admin/oauth/access_token";

$data = [
    "client_id" => $apiKey,
    "client_secret" => $apiSecret,
    "code" => $code
];

$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));
curl_setopt($ch, CURLOPT_HTTPHEADER, ["Content-Type: application/json"]);

$response = curl_exec($ch);
curl_close($ch);

$responseData = json_decode($response, true);

if (isset($responseData['access_token'])) {
    saveAccessToken($responseData['access_token']);
    echo "App installed successfully!";
} else {
    print_r($responseData);
}

📁 config.php

<?php
$apiKey = "YOUR_API_KEY";
$apiSecret = "YOUR_API_SECRET";

$accessTokenFile = __DIR__ . '/access_token.txt';

function saveAccessToken($token) {
    global $accessTokenFile;
    file_put_contents($accessTokenFile, $token);
}

function getAccessToken() {
    global $accessTokenFile;
    return file_exists($accessTokenFile) ? file_get_contents($accessTokenFile) : null;
}

🧾 Step 3: Create Registration Form

📁 customer_register.php

<form method="POST" action="https://yourdomain.com/register_customer.php">

  <input name="first_name" placeholder="First Name" required>
  <input name="last_name" placeholder="Last Name" required>
  <input name="email" type="email" required>
  <input name="phone" placeholder="Phone">

  <input name="company" placeholder="Company">
  <input name="address" placeholder="Address">

  <select name="country" required>
    <option value="United States">United States</option>
    <option value="Canada">Canada</option>
    <option value="Mexico">Mexico</option>
  </select>

  <input name="state" placeholder="State">
  <input name="postal_code" placeholder="Postal Code">

  <input name="eni_code" placeholder="ENI Code">
  <input name="instagram" placeholder="Instagram">
  <input name="facebook" placeholder="Facebook">
  <input name="tiktok" placeholder="TikTok">
  <input name="website" placeholder="Website">

  <button type="submit">Register</button>
</form>

⚙️ Step 4: Create Customer + Save Metafields

📁 register_customer.php

<?php
include 'config.php';

$accessToken = getAccessToken();
$shop = "your-store.myshopify.com";

if (!$accessToken) {
    die("Install app first");
}

$firstName = $_POST['first_name'];
$lastName = $_POST['last_name'];
$email = $_POST['email'];
$phone = $_POST['phone'];

$company = $_POST['company'];
$address = $_POST['address'];
$country = $_POST['country'];
$state = $_POST['state'];
$postal = $_POST['postal_code'];

$eni = $_POST['eni_code'];
$instagram = $_POST['instagram'];
$facebook = $_POST['facebook'];
$tiktok = $_POST['tiktok'];
$website = $_POST['website'];

$customerData = [
    "customer" => [
        "first_name" => $firstName,
        "last_name" => $lastName,
        "email" => $email,
        "phone" => $phone,
        "verified_email" => true,
        "tags" => "wholesale",
        "addresses" => [
            [
                "address1" => $address,
                "city" => "N/A",
                "province" => $state,
                "country" => $country,
                "zip" => $postal,
                "company" => $company
            ]
        ]
    ]
];

$ch = curl_init("https://$shop/admin/api/2024-01/customers.json");

curl_setopt($ch, CURLOPT_HTTPHEADER, [
    "Content-Type: application/json",
    "X-Shopify-Access-Token: $accessToken"
]);

curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($customerData));

$response = curl_exec($ch);
curl_close($ch);

$data = json_decode($response, true);

if (!isset($data['customer']['id'])) {
    print_r($data);
    exit;
}

$customerId = "gid://shopify/Customer/" . $data['customer']['id'];

🧩 Step 5: Save Custom Fields (Metafields)

$graphql = <<<GQL
mutation {
  metafieldsSet(metafields: [
    { ownerId: "$customerId", namespace: "custom", key: "eni_code", type: "single_line_text_field", value: "$eni" },
    { ownerId: "$customerId", namespace: "custom", key: "instagram", type: "single_line_text_field", value: "$instagram" },
    { ownerId: "$customerId", namespace: "custom", key: "facebook", type: "single_line_text_field", value: "$facebook" },
    { ownerId: "$customerId", namespace: "custom", key: "tiktok", type: "single_line_text_field", value: "$tiktok" },
    { ownerId: "$customerId", namespace: "custom", key: "website", type: "single_line_text_field", value: "$website" }
  ]) {
    metafields { key value }
    userErrors { message }
  }
}
GQL;

🎉 Step 6: Success Message (Popup)

After successful registration:

echo "Registration successful! We will review your account.";

Or use a modal popup for better UX.

🌐 Step 7: Show Form in Shopify Frontend

You have 2 options:

Option 1 (Simple)

Create a Shopify page and embed:

<iframe src="https://yourdomain.com/customer_register.php" width="100%" height="800"></iframe>

Option 2 (Better)

Use Shopify theme + AJAX (advanced)

🧠 Important Notes

• Shopify does NOT allow duplicate emails

• Phone must be in international format (+123456789)

• Country must match Shopify-supported values

• Custom fields must be saved using metafields

✅ Final Result

After setup:

✔ Customer is created
✔ Tagged as wholesale
✔ Custom data saved via metafields
✔ Form works on frontend
✔ Ready for approval workflow

🚀 What You Can Build Next

• Admin approval system

• Auto email after registration

• Show metafields in customer account

• Wholesale pricing access control

🎯 Conclusion

You’ve now built a fully functional Shopify custom registration system using PHP without any frameworks.

This approach gives you full control over:

• Customer onboarding

• Data collection

• Wholesale workflows

If you want to extend this further, you can integrate:

• Shopify Webhooks

• Admin dashboards

• React-based embedded apps

Happy coding! 🚀

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