Entity Mapper

The entity mapper is used to hydrate an array of data, usually from json_decode via a web service, to custom nested PHP objects.

To map the array to PHP objects you need to provide a map describing how the data should be transformed.

Features

• Simple way to transform raw data into your objects
• Provides a way to use bespoke objects rather than accessing a large array
• Helps to keep all your business logic in domain models
• No inheritance required on your objects
• Can hydrate complex / nested arrays

Setup

The constructor takes the raw data array and an allowAutoPropertySetting option - Whether a property with the same name as the data key should be auto set:

• true: properties will be mapped automatically if they have the same name
• false: you have to explicitly add properties to the map

Mapping array

The main way to control the hydration is through the mapping array. Each top level key corresponds to a PHP class and the value is an array consisting of the input data keys.

Each input data key has an array to describe how to deal with it:

• name: (string) The object property name the data will be mapped to.
• class: (string) Name of the class to be mapped to (optional)

Example

<?php

require_once  __DIR__.'/../src/EntityMapper/Mapper.php';
require_once  __DIR__.'/Tweet.php';

use EntityMapper\mapper;

// Fetch the data
$contents = file_get_contents('http://search.twitter.com/search.json?q=london&rpp=5');
$tweetsContainer = json_decode($contents, true);


// Provide the mapping
$map = array(
    'Tweet' => array(
        'from_user_name' => array('name' => 'userName'),
        'created_at' => array('name' => 'createdAt', 'class' => 'DateTime')
    )
);

// Create the mapper - seting the mapper to automatically set properties of the same name
$mapper = new Mapper($map, true);

// Hydrate the twitter data to 'Tweet' objects at a depth of 1
$tweets = $mapper->hydrate($tweetsContainer['results'], 'Tweet', 1);

// Use the new objects
foreach ($tweets as $tweet) {
    echo "\n\n" . $tweet->getUserName() . ' - ' . $tweet->getCreatedAt() ;
    echo "\n ---> " . $tweet->getText();
}

Result:

Daniel Chandra - Wednesday 28th of December 2011
 ---> RT @simplepassing: Cant wait for next (year) London derby, West Ham vs Chelsea :p RT @TruebluesIndo: *uhuk adminnya westham toh, ngeri juga kaya hooligan NYA

Advanced Usage

Depth property

Sometime the data you're interested in is nested within arrays. You can use the depth property to tell the mapper to only hydrate at a certain nested level.

_new function

The _new function can be used to customise the creation of objects. The function is passed the raw child data and the last key string which helps give it context.

<?php
// If you add a '_new' function to the map you can customise an object's creation.
// The function is passed the data and last string array key which is usefiul for deciding what object to create.
// So a complex array structure like array-Tweet-Entities-array['urls']-array-url can be hydrated pretty easily.

$createEntity = function($data, $lastStringKey) {
    switch ($lastStringKey) {
        case 'hashtags':
            return new Hash;
        case 'urls':
            return new Url;
    }
};

$map = array(
    'Tweet' => array(
        'from_user_name' => array('name' => 'userName'),
        'created_at' => array('name' => 'createdAt', 'class' => 'DateTime'),
        'entities'=> array('name' => 'entities', 'class' => 'Entity', 'depth' => 2)
    ),
    'Entity' => array('_new' => $createEntity)
);