Category: Development

cURL is a library for transferring data using various protocols – in this case most importantly HTTP POST and GET. PHP installed on a Linux distribution or as part of XAMPP uses libcurl. If you haven’t enabled cURL yet, open your php.ini and remove the semicolon at the beginning of this line:

;extension=php_curl.dll
^--- remove this semicolon

You will find the location of your php.ini in the output’s first line when running

php --ini

on the command line or by using the XAMPP control panel on a Windows machine. Click the ‘Config’ button next to the Apache module and select ‘PHP (php.ini)’ from the context menu. Save the changes and restart Apache – either by pressing ‘Stop’ & ‘Start’ on the XAMPP control panel or by using the Linux command line:

sudo service apache2 restart

If cURL for PHP isn’t installed, run

sudo apt-get install php-curl

 prior to the step above.

You’ll find further information on how to use cURL here: http://php.net/manual/en/book.curl.php

This boilerplate wraps cURL in a simple function with four parameters: request type, url, parameters and headers. The first snippet contains comments for every step. The second snippet is exactly the same code but without any comments.

Commented boilerplate:

<?php
 
$url = 'http://httpbin.org/post';
 
$parameters = array(
      'firstKey' => 'firstValue',
      'secondKey' => 'secondValue',
      'thirdKey' => 'thirdValue'
);
 
$headers = array(
      'X-Custom: 123',
      'X-Api-Key: ABC123'
);
 
// fire the request. Access the response object with $response->success and $response->body
$response = request('POST', $url, $parameters, $headers);

     
/**
 * cURL a resource with parameters
 *
 * @param string $requestType The request type POST or GET  
 * @param string $url The request URL
 * @param array|null $parameters An array of request parameters
 * 
 * @return object Response object with $success (bool) and $body (string) property.
 */ 
function request($requestType, $url, $parameters = null, $headers = null){
 
      // instantiate the response object
      $response = new stdClass();

      // check if cURL is enabled
      if(!function_exists('curl_init')){

            $response->success = false;
            $response->body = 'cURL is not enabled.';

            return $response;
      }
 
      // instantiate a cURL instance and set the handle
      $ch = curl_init();
 
      // build http query if $parameters is not null. Parameters with null as value will be removed from query.
      ($parameters !== null) ? $query = http_build_query($parameters) : $query = '';
 
      // POST:
      if($requestType === 'POST'){
 
            // 1 tells libcurl to do a regular HTTP post and sets a "Content-Type: application/www-form-urlencoded" header by default
            curl_setopt($ch,CURLOPT_POST, 1);                
            // add the query as POST body
            curl_setopt($ch,CURLOPT_POSTFIELDS, $query);     
            
      // GET:
      }elseif ($requestType === 'GET') {
      
            // if not empty, add parameters to URL
            if($query) $url = $url . '?' . $query;                
               
      // ELSE: 
      }else{
 
            $response->success = false;
            $response->body = 'request type GET or POST is missing.';

            return $response;
      }
      
      // set the URL
      curl_setopt($ch, CURLOPT_URL, $url);                  
      // tell cURL to return the response body. A successful request will return true if not set.
      curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);       
      // disable ssl certificate checks. Dirty, insecure workaround for common error "SSL Error: unable to get local issuer certificate". Fix it the correct way and remove the line!
      curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);      
      // more options here: http://php.net/manual/en/function.curl-setopt.php
 
      // add headers if present
      if ($headers !== null) curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

      // execute and store the result
      $result = curl_exec($ch);                             
 
      // check if request was successful. If yes, return result. If not, return error and its code.
      if($result !== false){

            $response->success = true;
            $response->body = $result;

      }else{

            $response->success = false;
            $response->body = curl_error($ch);
            $response->error = curl_errno($ch);
      }                  
      
      // close session and delete handle
      curl_close($ch);                                      

      // return response object
      return $response;                                       
}
 
 
 
?>

 

And the raw template without comments:

<?php
 
$url = 'http://httpbin.org/post';
 
$parameters = array(
      'firstKey' => 'firstValue',
      'secondKey' => 'secondValue',
      'thirdKey' => 'thirdValue'
);
 
$headers = array(
      'X-Custom: 123',
      'X-Api-Key: ABC123'
);
 

$response = request('POST', $url, $parameters, $headers);


function request($requestType, $url, $parameters = null, $headers = null){
 
      $response = new stdClass();

      if(!function_exists('curl_init')){

            $response->success = false;
            $response->body = 'cURL is not enabled.';

            return $response;
      }
 
      $ch = curl_init();
 
      ($parameters !== null) ? $query = http_build_query($parameters) : $query = '';
 
      if($requestType === 'POST'){
 
            curl_setopt($ch,CURLOPT_POST, 1);                
            curl_setopt($ch,CURLOPT_POSTFIELDS, $query);  

      }elseif ($requestType === 'GET') {

            if($query) $url = $url . '?' . $query;

      }else{
 
            $response->success = false;
            $response->body = 'request type GET or POST is missing.';

            return $response;
      }
      
      curl_setopt($ch, CURLOPT_URL, $url);                  
      curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);       
      curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);      
 
      if ($headers !== null) curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

      $result = curl_exec($ch);                             

      if($result !== false){

            $response->success = true;
            $response->body = $result;

      }else{

            $response->success = false;
            $response->body = curl_error($ch);
            $response->error = curl_errno($ch);
      }                  
      
      curl_close($ch);                                      

      return $response;                                       
}
 
 
 
?>