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PHP, cURL, and HTTP POST example?

Can anyone show me how to do a PHP cURL with an HTTP POST?

I want to send data like this:

username=user1, password=passuser1, gender=1

To www.example.com

I expect the cURL to return a response like result=OK. Are there any examples?


m
mimarcel
<?php
//
// A very simple PHP example that sends a HTTP POST to a remote site
//

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL,"http://www.example.com/tester.phtml");
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS,
            "postvar1=value1&postvar2=value2&postvar3=value3");

// In real life you should use something like:
// curl_setopt($ch, CURLOPT_POSTFIELDS, 
//          http_build_query(array('postvar1' => 'value1')));

// Receive server response ...
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$server_output = curl_exec($ch);

curl_close ($ch);

// Further processing ...
if ($server_output == "OK") { ... } else { ... }
?>

no need to use http_build_query() to handle parameters; just pass the array to CURLOPT_POSTFIELDS is enough.
@Raptor providing array directly to CURLOPT_POSTFIELDS actually curl makes slightly different type of POST. (Expect: 100-continue)
Also if value of CURLOPT_POSTFIELDS is an array, the Content-Type header will be set to multipart/form-data instead of application/x-www-form-urlencoded. php.net/manual/en/function.curl-setopt.php
Using CURLOPT_RETURNTRANSFER means that curl_exec will return the response as a string rather than outputting it.
I suggest using true instead of 1 for CURLOPT_POST.
e
emix

Procedural

// set post fields
$post = [
    'username' => 'user1',
    'password' => 'passuser1',
    'gender'   => 1,
];

$ch = curl_init('http://www.example.com');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post);

// execute!
$response = curl_exec($ch);

// close the connection, release resources used
curl_close($ch);

// do anything you want with your response
var_dump($response);

Object oriented

<?php

// mutatis mutandis
namespace MyApp\Http;

class CurlPost
{
    private $url;
    private $options;
           
    /**
     * @param string $url     Request URL
     * @param array  $options cURL options
     */
    public function __construct($url, array $options = [])
    {
        $this->url = $url;
        $this->options = $options;
    }

    /**
     * Get the response
     * @return string
     * @throws \RuntimeException On cURL error
     */
    public function __invoke(array $post)
    {
        $ch = \curl_init($this->url);
        
        foreach ($this->options as $key => $val) {
            \curl_setopt($ch, $key, $val);
        }

        \curl_setopt($ch, \CURLOPT_RETURNTRANSFER, true);
        \curl_setopt($ch, \CURLOPT_POSTFIELDS, $post);

        $response = \curl_exec($ch);
        $error    = \curl_error($ch);
        $errno    = \curl_errno($ch);
        
        if (\is_resource($ch)) {
            \curl_close($ch);
        }

        if (0 !== $errno) {
            throw new \RuntimeException($error, $errno);
        }
        
        return $response;
    }
}

Usage

// create curl object
$curl = new \MyApp\Http\CurlPost('http://www.example.com');

try {
    // execute the request
    echo $curl([
        'username' => 'user1',
        'password' => 'passuser1',
        'gender'   => 1,
    ]);
} catch (\RuntimeException $ex) {
    // catch errors
    die(sprintf('Http error %s with code %d', $ex->getMessage(), $ex->getCode()));
}

Side note here: it would be best to create some kind of interface called AdapterInterface for example with getResponse() method and let the class above implement it. Then you can always swap this implementation with another adapter of your like, without any side effects to your application.

Using HTTPS / encrypting traffic

Usually there's a problem with cURL in PHP under the Windows operating system. While trying to connect to a https protected endpoint, you will get an error telling you that certificate verify failed.

What most people do here is to tell the cURL library to simply ignore certificate errors and continue (curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);). As this will make your code work, you introduce huge security hole and enable malicious users to perform various attacks on your app like Man In The Middle attack or such.

Never, ever do that. Instead, you simply need to modify your php.ini and tell PHP where your CA Certificate file is to let it verify certificates correctly:

; modify the absolute path to the cacert.pem file
curl.cainfo=c:\php\cacert.pem

The latest cacert.pem can be downloaded from the Internet or extracted from your favorite browser. When changing any php.ini related settings remember to restart your webserver.


This should really be the accepted answer, because best-practice would be to let the HTTP library handle the encoding of your variables.
This is not always the case. I've seen web servers that expect POST variables to be encoded in a certain way, causing them to fail otherwise. It seems to me that http_build_query() is actually more reliable than cURL for this.
HTTP spec is pretty straightforward on how the POST parameters should look like. The webserver software should comply to standards anyway.
By using this way you will force cURL to use slightly different type of POST. (Expect: 100-continue). Check this article: support.urbanairship.com/entries/…
Expanding on @César's comment, the PHP documentation explicitly notes the following: "Passing an array to CURLOPT_POSTFIELDS will encode the data as multipart/form-data, while passing a URL-encoded string will encode the data as application/x-www-form-urlencoded.". I recently spent an inordinate amount of time trying to troubleshoot why a cURL call was failing on a third-party endpoint only to eventually realize that they did not support multipart/form-data.
E
Eric Leschinski

A live example of using php curl_exec to do an HTTP post:

Put this in a file called foobar.php:

<?php
  $ch = curl_init();
  $skipper = "luxury assault recreational vehicle";
  $fields = array( 'penguins'=>$skipper, 'bestpony'=>'rainbowdash');
  $postvars = '';
  foreach($fields as $key=>$value) {
    $postvars .= $key . "=" . $value . "&";
  }
  $url = "http://www.google.com";
  curl_setopt($ch,CURLOPT_URL,$url);
  curl_setopt($ch,CURLOPT_POST, 1);                //0 for a get request
  curl_setopt($ch,CURLOPT_POSTFIELDS,$postvars);
  curl_setopt($ch,CURLOPT_RETURNTRANSFER, true);
  curl_setopt($ch,CURLOPT_CONNECTTIMEOUT ,3);
  curl_setopt($ch,CURLOPT_TIMEOUT, 20);
  $response = curl_exec($ch);
  print "curl response is:" . $response;
  curl_close ($ch);
?>

Then run it with the command php foobar.php, it dumps this kind of output to screen:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" 
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Title</title>

<meta http-equiv="Pragma" content="no-cache">
<meta http-equiv="Expires" content="0">
<body>
  A mountain of content...
</body>
</html>

So you did a PHP POST to www.google.com and sent it some data.

Had the server been programmed to read in the post variables, it could decide to do something different based upon that.


$postvars .= $key . $value; should $postvars .= $key . $value ."&"; or not?
Looking again at this answer, you can also replace your custom query string converter implementation with http_build_query, just give it the $fields array and it'll output a query string.
Be aware that you should encode your data in order for it to be submitted safely.
Oh no don't try to build the post string yourself! use this: curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($fields));
-1 because you are not escaping your post vars. The OP's example is sending user-submitted usernames and passwords for authentication. With your solution, a user with an & in their password will never be able to log in. oriadam's comment is correct, but you can leave out http_build_query like: curl_setopt($ch, CURLOPT_POSTFIELDS, $fields);
c
cn007b

It's can be easily reached with:

<?php

$post = [
    'username' => 'user1',
    'password' => 'passuser1',
    'gender'   => 1,
];
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'http://www.domain.com');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post));
$response = curl_exec($ch);
var_export($response);

M
MSS

Curl Post + Error Handling + Set Headers [thanks to @mantas-d]:

function curlPost($url, $data=NULL, $headers = NULL) {
    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

    if(!empty($data)){
        curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
    }

    if (!empty($headers)) {
        curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    }

    $response = curl_exec($ch);

    if (curl_error($ch)) {
        trigger_error('Curl Error:' . curl_error($ch));
    }

    curl_close($ch);
    return $response;
}


curlPost('google.com', [
    'username' => 'admin',
    'password' => '12345',
]);

Your code won't close the handle and free resources, because you curl_close after throwing an exception. You should curl_close inside a finally block.
P
Pejman Kheyri

1.Step by step

Initialize the cURL session:

$url = "www.domain.com";
$ch = curl_init($url);

If your request has headers like bearer token or defining JSON contents you have to set HTTPHEADER options to cURL:

$token = "generated token code";
curl_setopt(
    $ch, 
    CURLOPT_HTTPHEADER, 
    array(
        'Content-Type: application/json', // for define content type that is json
        'bearer: '.$token, // send token in header request
        'Content-length: 100' // content length for example 100 characters (can add by strlen($fields))
    )
);

If you want to include the header in the output set CURLOPT_HEADER to true:

curl_setopt($ch, CURLOPT_HEADER, false);

Set RETURNTRANSFER option to true to return the transfer as a string instead of outputting it directly:

curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

To check the existence of a common name in the SSL peer certificate can be set to 0(to not check the names), 1(not supported in cURL 7.28.1), 2(default value and for production mode):

curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);

For posting fields as an array by cURL:

$fields = array(
    "username" => "user1",
    "password" => "passuser1",
    "gender" => 1
);
curl_setopt($ch, CURLOPT_POSTFIELDS, $fields);

Execute cURL and return the string. depending on your resource this returns output like result=OK:

$result = curl_exec($ch);

Close cURL resource, and free up system resources:

curl_close($ch);

2.Use as a class

The whole call_cURL class that can be extended:

class class_name_for_call_cURL {
    protected function getUrl() {
        return "www.domain.com";
    }

    public function call_cURL() {
        $token = "generated token code";

        $fields = array(
            "username" => "user1",
            "password" => "passuser1",
            "gender" => 1
        );

        $url = $this->getUrl();
        $output = $this->_execute($fields, $url, $token);
        
        // if you want to get json data
        // $output = json_decode($output);
            
        if ($output == "OK") {
            return true;
        } else {
             return false;
        }
    }

    private function _execute($postData, $url, $token) {
        // for sending data as json type
        $fields = json_encode($postData);

        $ch = curl_init($url);
        curl_setopt(
            $ch, 
            CURLOPT_HTTPHEADER, 
            array(
                'Content-Type: application/json', // if the content type is json
                'bearer: '.$token // if you need token in header
            )
        );
        curl_setopt($ch, CURLOPT_HEADER, false);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $fields);

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

        return $result;
    }
}

Using the class and call cURL:

$class = new class_name_for_call_cURL();
var_dump($class->call_cURL()); // output is true/false

3.One function

A function for using anywhere that needed:

function get_cURL() {

        $url = "www.domain.com";
        $token = "generated token code";

        $postData = array(
            "username" => "user1",
            "password" => "passuser1",
            "gender" => 1
        );

        // for sending data as json type
        $fields = json_encode($postData);

        $ch = curl_init($url);
        curl_setopt(
            $ch, 
            CURLOPT_HTTPHEADER, 
            array(
                'Content-Type: application/json', // if the content type is json
                'bearer: '.$token // if you need token in header
            )
        );
        curl_setopt($ch, CURLOPT_HEADER, false);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $fields);

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

        return $result;
}

This function is usable just by:

var_dump(get_cURL());

Hello @Pejman, how you going? I saw you good with this.. so could you take a look in my similar question? stackoverflow.com/questions/72122223/…
P
Polluks

I'm surprised nobody suggested file_get_contents:

$url = "http://www.example.com";
$parameters = array('username' => 'user1', 'password' => 'passuser1', 'gender' => '1');
$options = array('http' => array(
    'header'  => 'Content-Type: application/x-www-form-urlencoded\r\n',
    'method'  => 'POST',
    'content' => http_build_query($parameters)
));

$context  = stream_context_create($options);
$result = file_get_contents($url, false, $context);

it's simple, it works; I use it in an environment where I control the code at both ends.

even better, use json_decode (and set up your code to return JSON)

$result = json_decode(file_get_contents($url, false, $context), TRUE);

this approach invokes curl behind the scenes, but you don't jump through as many hoops.

Answer refined from this original answer elsewhere on Stack Overflow: PHP sending variables to file_get_contents()


This is a really great answer. However, it works for me only when I remove the content-type header part.
@lukas, the content-type header was added by an SO editor, not me...
Hello @cloudxix, how you going? I saw you good with this.. so could you take a look in my similar question? stackoverflow.com/questions/72122223/…
M
Mantas D
curlPost('google.com', [
    'username' => 'admin',
    'password' => '12345',
]);


function curlPost($url, $data) {
    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
    $response = curl_exec($ch);
    $error = curl_error($ch);
    curl_close($ch);
    if ($error !== '') {
        throw new \Exception($error);
    }

    return $response;
}

Your code won't close the handle and free resources, because you curl_close after throwing an exception. You should curl_close inside a finally block.
A
Anthony

If the form is using redirects, authentication, cookies, SSL (https), or anything else other than a totally open script expecting POST variables, you are going to start gnashing your teeth really quick. Take a look at Snoopy, which does exactly what you have in mind while removing the need to set up a lot of the overhead.


If you want to stick with the stock lib, just try adding curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
The only downside is that you still have to deal with setting a cookie jar and other potential issues (like whether to follow redirects, how to deal with non HTTP-based authentication, etc). 6 years later, I would recommend the more generic concept of a "headless-browser" instead of that specific library (or anything on sourceforge, how dated, right?) And while I generally just deal with curl options directly, I would still advise looking at a headless-browser library that is PSR-7 compatible (Guzzle is the only one I know off-hand) to avoid headaches.
a
andrewsi

A simpler answer IF you are passing information to your own website is to use a SESSION variable. Begin php page with:

session_start();

If at some point there is information you want to generate in PHP and pass to the next page in the session, instead of using a POST variable, assign it to a SESSION variable. Example:

$_SESSION['message']='www.'.$_GET['school'].'.edu was not found.  Please try again.'

Then on the next page you simply reference this SESSION variable. NOTE: after you use it, be sure you destroy it, so it doesn't persist after it is used:

if (isset($_SESSION['message'])) {echo $_SESSION['message']; unset($_SESSION['message']);}

A
AzizSM

Here are some boilerplate code for PHP + curl http://www.webbotsspidersscreenscrapers.com/DSP_download.php

include in these library will simplify development

<?php
# Initialization
include("LIB_http.php");
include("LIB_parse.php");
$product_array=array();
$product_count=0;

# Download the target (store) web page
$target = "http://www.tellmewhenitchanges.com/buyair";
$web_page = http_get($target, "");
    ...
?>

S
Serhii Andriichuk

Examples of sending form and raw data:

$curlHandler = curl_init();

curl_setopt_array($curlHandler, [
    CURLOPT_URL => 'https://postman-echo.com/post',
    CURLOPT_RETURNTRANSFER => true,

    /**
     * Specify POST method
     */
    CURLOPT_POST => true,

    /**
     * Specify array of form fields
     */
    CURLOPT_POSTFIELDS => [
        'foo' => 'bar',
        'baz' => 'biz',
    ],
]);

$response = curl_exec($curlHandler);

curl_close($curlHandler);

echo($response);

P
Pejman Kheyri

If you try to login on site with cookies.

This code:

if ($server_output == "OK") { ... } else { ... }

It May not works if you try to login, because many sites return status 200, but the post is not successful.

The easy way to check if the login post is successful is to check if it setting cookies again. If in output have a Set-Cookies string, this means the posts are not successful and it starts a new session.

Also, the post can be successful, but the status can redirect instead of 200.

To be sure the post is successful try this:

Follow location after the post, so it will go to the page where the post does redirect to:

curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);

And than check if new cookies existing in the request:

if (!preg_match('/^Set-Cookie:\s*([^;]*)/mi', $server_output)) 

{echo 'post successful'; }

else { echo 'not successful'; }

T
Tobias Ernst

Easiest is to send data as application/json. This will take an array as input and properly encodes it into a json string:

$data = array(
    'field1' => 'field1value',
    'field2' => 'field2value',
)

$ch = curl_init($url);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));

curl_setopt($ch, CURLOPT_HTTPHEADER, array(
    'Content-Type:application/json',
));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$resultStr = curl_exec($ch);
return json_decode($resultStr, true);