enable cors with php code example

Example 1: php access origin

<?php
 header("Access-Control-Allow-Origin: *");

Example 2: php strict-origin-when-cross-origin

header("Access-Control-Allow-Origin: *");

Example 3: php header allow cross origin

/**
 *  An example CORS-compliant method.  It will allow any GET, POST, or OPTIONS requests from any
 *  origin.
 *
 *  In a production environment, you probably want to be more restrictive, but this gives you
 *  the general idea of what is involved.  For the nitty-gritty low-down, read:
 *
 *  - https://developer.mozilla.org/en/HTTP_access_control
 *  - http://www.w3.org/TR/cors/
 *
 */
function cors() {

    // Allow from any origin
    if (isset($_SERVER['HTTP_ORIGIN'])) {
        // Decide if the origin in $_SERVER['HTTP_ORIGIN'] is one
        // you want to allow, and if so:
        header("Access-Control-Allow-Origin: {$_SERVER['HTTP_ORIGIN']}");
        header('Access-Control-Allow-Credentials: true');
        header('Access-Control-Max-Age: 86400');    // cache for 1 day
    }

    // Access-Control headers are received during OPTIONS requests
    if ($_SERVER['REQUEST_METHOD'] == 'OPTIONS') {

        if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_METHOD']))
            // may also be using PUT, PATCH, HEAD etc
            header("Access-Control-Allow-Methods: GET, POST, OPTIONS");         

        if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']))
            header("Access-Control-Allow-Headers: {$_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']}");

        exit(0);
    }

    echo "You have CORS!";
}

Example 4: cross origin even with allow header

header('Access-Control-Allow-Origin: http://localhost:8100');
header ("Access-Control-Expose-Headers: Content-Length, X-JSON");
header ("Access-Control-Allow-Methods: GET, POST, PATCH, PUT, DELETE, OPTIONS");
header ("Access-Control-Allow-Headers: Content-Type, Authorization, Accept, Accept-Language, X-Authorization");
header('Access-Control-Max-Age: 86400');

if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') {
    // The request is using the POST method
    header("HTTP/1.1 200 OK");
    return;

}

Example 5: Access to XMLHttpRequest at 'http://localhost/MySQL_pracs/InsertUser.php' from origin 'http://localhost:4200' has been blocked by CORS policy: Request header field content-type is not allowed by Access-Control-Allow-Headers in preflight response.

//Access to XMLHttpRequest at 'http://localhost/[api path].php' from origin 'http://localhost:4200' has been blocked by CORS policy: Request header field content-type is not allowed by Access-Control-Allow-Headers in preflight response.

//The error is simply saying that "Content-Type" is missing from "Access-Control-Allow-Headers".

//Therefore we need to add "Content-Type" to "Access-Control-Allow-Headers".

<?php 
header('Access-Control-Allow-Headers: Content-Type');
-----
?>

Example 6: laravel Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on

Step 1 : Create Cors middleware.
php artisan make:middleware Cors

Step 2 : Add below lines in handle function before return.
  //header('Access-Control-Allow-Origin:  *');
header('Access-Control-Allow-Origin:  http://localhost:4200');
header('Access-Control-Allow-Headers:  Content-Type, X-Auth-Token, Authorization, Origin');
header('Access-Control-Allow-Methods:  POST, PUT');

Step 3 : Register the middileware in app/Http/Kernel.php file
  
  Add below line in $middleware array 

 \App\Http\Middleware\Cors::class,

Step 4 : Now we have to call the middleware in app/Http/Kernel.php file
  Add below line in $routeMiddleware array 

'cors' => \App\Http\Middleware\Cors::class,



Using the * works rather than the host origin. Was missing the Cors.php middleware in the array as well