git clone https://github.com/justinrainbow/json-schema.git

composer require justinrainbow/json-schema

<?php

$data = json_decode(file_get_contents('data.json'));

// Validate
$validator = new JsonSchema\Validator;
$validator->validate($data, (object)['$ref' => 'file://' . realpath('schema.json')]);

if ($validator->isValid()) {
    echo "The supplied JSON validates against the schema.\n";
} else {
    echo "JSON does not validate. Violations:\n";
    foreach ($validator->getErrors() as $error) {
        echo sprintf("[%s] %s\n", $error['property'], $error['message']);
    }
}

<?php

use JsonSchema\SchemaStorage;
use JsonSchema\Validator;
use JsonSchema\Constraints\Factory;
use JsonSchema\Constraints\Constraint;

$request = (object)[
    'processRefund'=>"true",
    'refundAmount'=>"17"
];

$validator->validate(
    $request, (object) [
    "type"=>"object",
        "properties"=>(object)[
            "processRefund"=>(object)[
                "type"=>"boolean"
            ],
            "refundAmount"=>(object)[
                "type"=>"number"
            ]
        ]
    ],
    Constraint::CHECK_MODE_COERCE_TYPES
); // validates!

is_bool($request->processRefund); // true
is_int($request->refundAmount); // true

$validator->coerce($request, $schema);
// equivalent to $validator->validate($data, $schema, Constraint::CHECK_MODE_COERCE_TYPES);

<?php

use JsonSchema\Validator;
use JsonSchema\Constraints\Constraint;

$request = (object)[
    'refundAmount'=>17
];

$validator = new Validator();

$validator->validate(
    $request,
    (object)[
        "type"=>"object",
        "properties"=>(object)[
            "processRefund"=>(object)[
                "type"=>"boolean",
                "default"=>true
            ]
        ]
    ],
    Constraint::CHECK_MODE_APPLY_DEFAULTS
); //validates, and sets defaults for missing properties

is_bool($request->processRefund); // true
$request->processRefund; // true

<?php

use JsonSchema\SchemaStorage;
use JsonSchema\Validator;
use JsonSchema\Constraints\Factory;

$jsonSchema = <<<'JSON'
{
    "type": "object",
    "properties": {
        "data": {
            "oneOf": [
                { "$ref": "#/definitions/integerData" },
                { "$ref": "#/definitions/stringData" }
            ]
        }
    },
    "required": ["data"],
    "definitions": {
        "integerData" : {
            "type": "integer",
            "minimum" : 0
        },
        "stringData" : {
            "type": "string"
        }
    }
}
JSON;

// Schema must be decoded before it can be used for validation
$jsonSchemaObject = json_decode($jsonSchema);

// The SchemaStorage can resolve references, loading additional schemas from file as needed, etc.
$schemaStorage = new SchemaStorage();

// This does two things:
// 1) Mutates $jsonSchemaObject to normalize the references (to file://mySchema#/definitions/integerData, etc)
// 2) Tells $schemaStorage that references to file://mySchema... should be resolved by looking in $jsonSchemaObject
$schemaStorage->addSchema('file://mySchema', $jsonSchemaObject);

// Provide $schemaStorage to the Validator so that references can be resolved during validation
$jsonValidator = new Validator( new Factory($schemaStorage));

// JSON must be decoded before it can be validated
$jsonToValidateObject = json_decode('{"data":123}');

// Do validation (use isValid() and getErrors() to check the result)
$jsonValidator->validate($jsonToValidateObject, $jsonSchemaObject);

composer test                            # run all unit tests
composer testOnly TestClass              # run specific unit test class
composer testOnly TestClass::testMethod  # run specific unit test method
composer style-check                     # check code style for errors
composer style-fix                       # automatically fix code style errors