PHP GET Requests for Mobile Apps

TL;DR

Use PHP’s $_GET superglobal to receive data from mobile apps via HTTP GET requests. Sanitize all input to prevent security vulnerabilities. Return JSON-formatted responses for easy parsing on the app side.

1. Understanding HTTP GET Requests

HTTP GET requests are used to retrieve data from a server. When a mobile app makes a GET request, it includes parameters in the URL after a question mark (?). These parameters are key-value pairs separated by ampersands (&).

Example:

https://yourserver.com/api/data.php?name=John&age=30

2. Receiving Data in PHP

PHP provides the $_GET superglobal array to access these parameters.

1. Accessing Parameters: Each parameter is stored as an element in the $_GET array, using the parameter name as the key.

Important: Always check if the parameters exist before using them to avoid errors.

3. Data Sanitization

Crucially important for cyber security! Never trust data received from the client (mobile app). Sanitize all input to prevent attacks like cross-site scripting (XSS) and SQL injection.

1. htmlspecialchars(): Escape special characters in strings.
2. intval(): Convert values to integers.
3. filter_var(): Validate and sanitize data based on specific filters (e.g., email, URL).

4. Returning JSON Responses

Mobile apps typically prefer data in JSON format. Use PHP’s json_encode() function to convert your data into a JSON string.

1. Create an Associative Array: Store the data you want to return in an associative array.
2. Encode to JSON: Use json_encode() to convert the array to a JSON string.
3. Set Content Type Header: Set the Content-Type header to application/json so the app knows how to interpret the response.

 htmlspecialchars($_GET['name']),
  'age' => intval($_GET['age'])
);

echo json_encode($data);
?>

5. Example Complete Script

 'success',
    'name' => $name,
    'age' => $age
  );

echo json_encode($data);
} else {
  $data = array('status' => 'error', 'message' => 'Missing parameters');
echo json_encode($data);
}
?>

6. Security Considerations

• HTTPS: Always use HTTPS to encrypt communication between the app and server.
• Rate Limiting: Implement rate limiting to prevent abuse.
• Input Validation: Thoroughly validate all input data on the server-side.
• Error Handling: Handle errors gracefully and avoid exposing sensitive information in error messages.