Posting multidimensional array with PHP and CURL

Question

I\'m having trouble posting form data via CURL to a receiving PHP script located on a different host.

I get an Array to string conversion error

Answer 1

First I would like to thank Daniel Vandersluis for his insightful reply. Based on his input I came up with this to fix the problem from the original question:

<?php

function curl_postfields_flatten($data, $prefix = '') {
  if (!is_array($data)) {
    return $data; // in case someone sends an url-encoded string by mistake
  }

  $output = array();
  foreach($data as $key => $value) {
    $final_key = $prefix ? "{$prefix}[{$key}]" : $key;
    if (is_array($value)) {
      // @todo: handle name collision here if needed
      $output += curl_postfields_flatten($value, $final_key);
    }
    else {
      $output[$final_key] = $value;
    }
  }
  return $output;
}

Usage should look like this:

curl_setopt($this->ch, CURLOPT_POSTFIELDS, curl_postfields_flatten($post));

This function will convert arrays like this:

array(
  'a' => 'a',
  'b' => array(
    'c' => array(
      'd' => 'd',
      'e' => array(
        'f' => 'f',
      ),
    ),
  ),
);

Into this:

array(
  'a' => 'a',
  'b[c][d]' => 'd',
  'b[c][e][f]' => 'f',
)

It doesn't handle cases with mixed format when there is a key collision like this:

array(
 'b[c]' => '1',
 'b' => array(
   'c' => '2', 
  ),
);

The output will contain only the first value for that key

array(
 'b[c]' => '1'
)

Answer 2

You'd have to build the POST string manually, rather than passing the entire array in. You can then override curl's auto-chose content header with:

curl_setopt($c, CURLOPT_HTTPHEADER, array("Content-type: multipart/form-data"));

Serializing/json-ifying would be easier, but as you say, you have no control over the receiving end, so you've got a bit of extra work to do.

Answer 3

Simplest solution is to do a :

$array = urldecode(http_build_query($array));

Below is sample code where this is used in real life :

https://gist.github.com/gayanhewa/142c48162f72e68a4a23

When you have nested $params section in the above gist it will parse it accordingly and prepare it for posting via curl.

Answer 4

function http_build_query_for_curl( $arrays, &$new = array(), $prefix = null ) {

    if ( is_object( $arrays ) ) {
        $arrays = get_object_vars( $arrays );
    }

    foreach ( $arrays AS $key => $value ) {
        $k = isset( $prefix ) ? $prefix . '[' . $key . ']' : $key;
        if ( is_array( $value ) OR is_object( $value )  ) {
            http_build_query_for_curl( $value, $new, $k );
        } else {
            $new[$k] = $value;
        }
    }
}

$arrays = array(
    'name' => array(
        'first' => array(
            'Natali', 'Yura'
        )
    )
);


http_build_query_for_curl( $arrays, $post );

print_r($post);

Answer 5

The cURL option CURLOPT_POSTFIELDS will accept either a string or simple array but not a nested array. Attempting to do so will generate the Array to string conversion error.

However http_build_query() can handle a nested array so use it to convert the $_POST array to a string then send that string instead. So where you have;

curl_setopt($ch, CURLOPT_POSTFIELDS, $_POST);

use this instead;

curl_setopt($ch, CURLOPT_POSTFIELDS, urldecode(http_build_query($_POST)));

Answer 6

$post = "ac=on&p=1&pr[]=0&pr[]=1&a[]=3&a[]=4&pl=on&sp[]=3&ct[]=3&s=1&o=0&pp=3&sortBy=date";
parse_str($post,$fields); 

$url = 'http://example.com/';


//open connection
$ch = curl_init();

//set the url, number of POST vars, POST data
curl_setopt($ch,CURLOPT_URL, $url);
curl_setopt($ch,CURLOPT_POST, true);
curl_setopt($ch,CURLOPT_POSTFIELDS, $fields);
curl_setopt($ch,CURLOPT_RETURNTRANSFER, true);

//execute post
$result = curl_exec($ch);

//close connection
curl_close($ch);