How PHP json_validate Function Will Improve The Validation of JSON Data in PHP 8.3

Why PHP needs a JSON Validation Built-In Function

JSON is a format that has become very popular among developers of different languages. It is often used to send and receive data structures to APIs that implement Web services.

Before PHP version 8.3, there was no built-in function that PHP developers could use to perform validation of a string that checks if it has a valid JSON data structure.

So PHP developers have used workarounds to validate JSON data strings. Although those workarounds work, they have inconveniences, such as using too much memory when JSON data strings are not small.

What Will the json_validate Will Do

The function json_validate is simple. It will take a JSON string and return whether it contains valid JSON data. More details about how the json_validate function will work are available on the json_validate function RFC page.

How you Can Benefit From the json_validate Function When it Will be Available

One common use case for this function is in implementing an API with parts that take a data structure as a parameter, like an object or an array. The data structure can be passed in JSON format.

Applications that implement that API can use json_validate to ensure the API client passes valid JSON data.

$api_parameter_data = '"some JSON data string"';

$valid = json_validate($api_parameter_data);

How You Can Implement a json_validate Emulation Function in Current PHP Versions

Before PHP 8.3 you could use the json_decode function to emulate the json_validate function. The json_decode function does more than the json_validate will do because it also parses and validate the JSON data.

A straightforward way to implement an emulation of the json_validate could look like this:

function emulate_json_validate($json, $depth = 512, int $flags = 0)
{
	$decoded = json_decode($json, false, $depth, $flags);
	return json_last_error() === JSON_ERROR_NONE;
}

Other implementations of similar functions emulate the json_validate function in the RFC page.