(PHP Extension) curl with Variable Substitution in a JSON Request Body

See more CURL Examples

This example shows how to use variables inside a JSON request body using the {{variable_name}} syntax. When the HTTP request’s Content-Type indicates JSON, Chilkat automatically applies proper JSON escaping to each substituted value, ensuring the resulting JSON remains valid.

Note: This example requires Chilkat v11.5.0 or greater.

Chilkat PHP Downloads

PHP Extension for Windows, Linux, MacOS, Alpine Linux

<?php

include("chilkat.php");

$success = false;

// Variable names are enclosed between {{ and }}
// Important: The variable {{var_name}} should be placed inside the quotes.

// This is correct:
// curl -X POST https://api.example.com/messages \
//   -H "Content-Type: application/json" \
//   -d '{"text":"{{message}}"}'

// This is incorrect:
//   -d '{"text":{{message}}}'

$sbCurl = new CkStringBuilder();
$sbCurl->AppendLn('curl -X POST https://api.example.com/messages \\');
$sbCurl->AppendLn('  -H \'Content-Type: application/json\' \\');
$sbCurl->AppendLn('  -d '{\'text\':\'{{message}}\'}'');

$curl = new CkHttpCurl();

// In this example, the value we'll provide for the "message" variable
// will contain chars that require JSON escaping.
$curl->SetVar('message','He said \'Hello, world!\'');

// To demonstrate how the variables are replaced, this example does not execute the curl command. 
// Instead, it generates the raw HTTP request that would be sent if the curl command were run.
$sbRawRequest = new CkStringBuilder();
$success = $curl->ToRawRequest($sbCurl->getAsString(),$sbRawRequest);
if ($success == false) {
    print $curl->lastErrorText() . "\n";
    exit;
}

print $sbRawRequest->getAsString() . "\n";

// The output is shown below.
// Notice that the quote chars around "Hello World!" are properly JSON escaped.

// POST /messages HTTP/1.1
// Host: api.example.com
// Content-Type: application/json
// Content-Length: 36
// 
// {"text":"He said \"Hello, world!\""}

?>