JsonMapper

This module provides a mapper to map JSON to PHP classes utilizing Symfony's property info and access packages.

Installation

Using Composer

To install using composer, just run the following command from the command line.

composer require magicsunday/jsonmapper

To remove the module run:

composer remove magicsunday/jsonmapper

Usage

PHP classes

In order to guarantee a seamless mapping of a JSON response into PHP classes you should prepare your classes well. Annotate all properties with the requested type.

In order to ensure correct mapping of a collection, the property has to be annotated using the phpDocumentor collection annotation type. A collection is a non-scalar value capable of containing other values.

For example:

@var SomeCollection<DateTime>
@var SomeCollection<string>
@var Collection\SomeCollection<App\Entity\SomeEntity>

Custom annotations

Sometimes its may be required to circumvent the limitations of a poorly designed API. Together with custom annotations it becomes possible to fix some API design issues (e.g. mismatch between documentation and webservice response), to create a clean SDK.

@MagicSunday\JsonMapper\Annotation\ReplaceNullWithDefaultValue

This annotation is used to inform the JsonMapper that an existing default value should be used when setting a property, if the value derived from the JSON is a NULL value instead of the expected property type.

This can be necessary, for example, in the case of a bad API design, if the API documentation defines a certain type (e.g. array), but the API call itself then returns NULL if no data is available for a property instead of an empty array that can be expected.

/**
 * @var array<string>
 *
 * @MagicSunday\JsonMapper\Annotation\ReplaceNullWithDefaultValue
 */
public array $array = [];

If the mapping tries to assign NULL to the property, the default value will be used, as annotated.

@MagicSunday\JsonMapper\Annotation\ReplaceProperty

This annotation is used to inform the JsonMapper to replace one or more properties with another one. It's used in class context.

For instance if you want to replace a cryptic named property to a more human-readable name.

/**
 * @MagicSunday\JsonMapper\Annotation\ReplaceProperty("type", replaces="crypticTypeNameProperty")
 */
class FooClass
{
    /**
     * @var string
     */
    public $type;
}

Instantiation

In order to create an instance of the JsonMapper you are required to pass some arguments to the constructor. The constructor requires an instance of \Symfony\Component\PropertyInfo\PropertyInfoExtractor and an instance of \Symfony\Component\PropertyAccess\PropertyAccessor. The other arguments are optional.

So first create instances of Symfony's property info extractors. Each list of extractors could contain any number of available extractors. You could also create your own extractors to adjust the process of extracting property info to your needs.

To use the PhpDocExtractor extractor you need to install the phpdocumentor/reflection-docblock library too.

use \Symfony\Component\PropertyInfo\Extractor\ReflectionExtractor;
use \Symfony\Component\PropertyInfo\Extractor\PhpDocExtractor;
use \Symfony\Component\PropertyInfo\PropertyInfoExtractor;
use \Symfony\Component\PropertyAccess\PropertyAccessor;

A common extractor setup:

$listExtractors = [ new ReflectionExtractor() ];
$typeExtractors = [ new PhpDocExtractor() ];
$propertyInfoExtractor = new PropertyInfoExtractor($listExtractors, $typeExtractors);

Create an instance of the property accessor:

$propertyAccessor = PropertyAccess::createPropertyAccessor();

Using the third argument you can pass a property name converter instance to the mapper. With this you can convert the JSON property names to you desired format your PHP classes are using.

$nameConverter = new \MagicSunday\JsonMapper\Converter\CamelCasePropertyNameConverter();

The last constructor parameter allows you to pass a class map to JsonMapper in order to change the default mapping behaviour. For instance if you have an SDK which maps the JSON response of a webservice to PHP. Using the class map you could override the default mapping to the SDK's classes by providing an alternative list of classes used to map.

$classMap = [
    SdkFoo::class => Foo::class,
];

Create an instance of the JsonMapper:

$mapper = new \MagicSunday\JsonMapper(
    $propertyInfoExtractor,
    $propertyAccessor,
    $nameConverter,
    $classMap
);

To handle custom or special types of objects, add them to the mapper. For instance to perform special treatment if an object of type Bar should be mapped:

$mapper->addType(
    Bar::class,
    /** @var mixed $value JSON data */
    static function ($value): ?Bar {
        return $value ? new Bar($value['name']) : null;
    }
);

or add a handler to map DateTime values:

$mapper->addType(
    \DateTime::class,
    /** @var mixed $value JSON data */
    static function ($value): ?\DateTime {
        return $value ? new \DateTime($value) : null;
    }
);

Convert a JSON string into a JSON array/object using PHPs built in method json_decode

$json = json_decode('JSON STRING', true, 512, JSON_THROW_ON_ERROR);

Call method map to do the actual mapping of the JSON object/array into PHP classes. Pass the initial class name and optional the name of a collection class to the method.

$mappedResult = $mapper->map($json, Foo::class, FooCollection::class);

A complete set-up may look like this:

/**
 * Returns an instance of the JsonMapper for testing.
 *
 * @param string[]|Closure[] $classMap A class map to override the class names
 *
 * @return \MagicSunday\JsonMapper
 */
protected function getJsonMapper(array $classMap = []): \MagicSunday\JsonMapper
{
    $listExtractors = [ new ReflectionExtractor() ];
    $typeExtractors = [ new PhpDocExtractor() ];
    $extractor      = new PropertyInfoExtractor($listExtractors, $typeExtractors);

    return new \MagicSunday\JsonMapper(
        $extractor,
        PropertyAccess::createPropertyAccessor(),
        new CamelCasePropertyNameConverter(),
        $classMap
    );
}

Development

Testing

composer update
composer ci:cgl
composer ci:test
composer ci:test:php:phplint
composer ci:test:php:phpstan
composer ci:test:php:rector
composer ci:test:php:unit