How to validate JSON in PHP?

Question

Is there any way to check that a variable is a valid JSON string in PHP without using json_last_error()? I don\'t have PHP 5.3.3.

Answer 1

If you want to check if your input is valid JSON, you might as well be interested in validating whether or not it follows a specific format, i.e a schema. In this case you can define your schema using JSON Schema and validate it using this library.

Example:

person.json

{
    "title": "Person",
    "type": "object",
    "properties": {
        "firstName": {
            "type": "string"
        },
        "lastName": {
            "type": "string"
        },
        "age": {
            "description": "Age in years",
            "type": "integer",
            "minimum": 0
        }
    },
    "required": ["firstName", "lastName"]
}

Validation

validate($data, (object)['$ref' => 'file://' . realpath('person.json')]);

$validator->isValid()