selective / transformer
A strictly typed array transformer with dot-access, fluent interface and filters.
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Requires
- php: ^8.1
Requires (Dev)
README
A strictly typed array transformer with dot access and fluent interface. The mapped result can be used for JSON responses and many other things.
Table of Contents
- Requirements
- Installation
- Introduction
- Dot access
- Transforming
- Mapping rules
- Filter
- Examples
- License
Requirements
- PHP 8.1+
Installation
composer require selective/transformer
Introduction
This Transformer component provides functionality to map, cast and loop array values from an array or object to another array.
Converting complex data with simple PHP works by using a lot of type casting, if conditions and looping through the
data with foreach(). This leads to very high cyclomatic complexity and nesting depth, and thus poor "code rating".
Before: Conditions: 9, Paths: 256, CRAP Score: 9
Click to expand!
After: Conditions: 1, Paths: 1, CRAP Score: 1
Click to expand!
Use Cases
When building an API it is common for people to just grab stuff from the database and pass it to json_encode(). This
might be passable for “trivial” APIs but if they are in use by the public, or used by mobile applications then this will
quickly lead to inconsistent output. The Transformer is able to create a “barrier” between source data and output, so
schema changes do not affect users.
The Transformer works also very well to put any kind of database resultset (e.g. from PDO) into a new data structure.
The uses cases are not limited.
Dot access
You can copy any data from the source array to any sub-element of the destination array using the dot-syntax.
<?php use Selective\Transformer\ArrayTransformer; $transformer = new ArrayTransformer(); $transformer->map('firstName', 'address.first_name') ->map('lastName', 'address.last_name') ->map('invoice.items', 'root.sub1.sub2.items'); // ...
Object access
It's possible to access the properties of an object using the dot notation.
use Selective\Transformer\ArrayTransformer; $transformer = new ArrayTransformer(); $transformer->map('bar1', 'foo.bar', 'string') ->map('bar2', 'foo.bar2.0', 'string') ->map('sub.sub2.sub3', 'foo.bar2.1', 'string'); $user = new stdClass(); $user->foo = new stdClass(); $user->foo->bar = 'Hello Bar'; $user->foo->bar2 = [ 0 => 'Test 0', 1 => 'Test 1', ]; $result = $transformer->toArray((array)$user);
The result:
[
'bar1' => 'Hello Bar',
'bar2' => 'Test 0',
'sub' => [
'sub2' => [
'sub3' => 'Test 1',
],
],
];
Transforming
Transforming arrays
For the sake of simplicity, this example has been put together as though it was one file. In reality, you would spread the manager initiation, data collection and JSON conversion into separate parts of your application.
Sample data:
$data = [ 'first_name' => 'Sally', 'last_name' => '', 'email' => 'sally@example.com', ];
<?php use Selective\Transformer\ArrayTransformer; $transformer = new ArrayTransformer(); $transformer->map('firstName', 'first_name') ->map('lastName', 'last_name') ->map('email', 'email'); $result = $transformer->toArray($data);
The result:
[
'firstName' => 'Sally',
'email' => 'sally@example.com',
];
Transforming list of arrays
The method toArrays is able to transform a list of arrays.
This can be useful if you want to transform a resultset from a database query, or a response payload from an API.
Example:
$transformer = new ArrayTransformer(); $transformer->map('id', 'id', $transformer->rule()->integer()) ->map('first_name', 'first_name', $transformer->rule()->string()) ->map('last_name', 'last_name', $transformer->rule()->string()) ->map('phone', 'phone', $transformer->rule()->string()) ->map('enabled', 'enabled', $transformer->rule()->boolean()); $rows = []; $rows[] = [ 'id' => '100', 'first_name' => 'Sally', 'last_name' => '', 'phone' => null, 'enabled' => '1', ]; $rows[] = [ 'id' => '101', 'first_name' => 'Max', 'last_name' => 'Doe', 'phone' => '+123456789', 'enabled' => '0', ]; $result = $transformer->toArrays($rows);
The result:
[
[
'id' => 100,
'first_name' => 'Sally',
'enabled' => true,
],
[
'id' => 101,
'first_name' => 'Max',
'last_name' => 'Doe',
'phone' => '+123456789',
'enabled' => false,
],
]
Mapping Rules
Simple mapping rules
Using strings, separated by |, to define a filter chain:
<?php use Selective\Transformer\ArrayTransformer; $transformer = new ArrayTransformer(); $transformer->map('firstName', 'first_name', 'string|required') ->map('lastName', 'last_name', 'string|required') ->map('email', 'email', 'string|required'); $data = [ 'first_name' => 'Sally', 'last_name' => '', 'email' => 'sally@example.com', ]; $result = $transformer->toArray($data);
Because lastName is blank but required the result looks like this:
[
'firstName' => 'Sally',
'lastName' => '',
'email' => 'sally@example.com',
];
Complex mapping rules
For complexer mapping rules there is a fluent interface available. To create a new rule use the rule method and pass
it as 3rd. parameter to the map method.
<?php use Selective\Transformer\ArrayTransformer; $transformer = new ArrayTransformer(); $transformer->map('firstName', 'first_name', $transformer->rule()->string()->required()) ->map('lastName', 'last_name', $transformer->rule()->string()->required()) ->map('email', 'email', $transformer->rule()->string()->required()); $data = [ 'first_name' => 'Sally', 'last_name' => '', 'email' => 'sally@example.com', ]; $result = $transformer->toArray($data);
Because lastName is blank but required the result looks like this:
[
'firstName' => 'Sally',
'lastName' => '',
'email' => 'sally@example.com',
];
Filter
Most filters are directly available as method.
// Cast value to string, convert blank to null $transformer->rule()->string(); // Cast value to string, allow blank string '' $transformer->rule()->string(true); // Cast value to int $transformer->rule()->integer(); // Cast value to float $transformer->rule()->float(); // Cast value to bool $transformer->rule()->boolean(); // Cast value to datetime string, default: Y-m-d H:i:s $transformer->rule()->date(); // Cast value to date string $transformer->rule()->date('Y-m-d'); // Format value to number using the number_format function $transformer->rule()->number(); // Format value to number with a custom number format $transformer->rule()->number(2, '.', ','); // Cast value to array $transformer->rule()->array(); // Cast value using a custom callback function $transformer->rule()->callback( function ($value) { return 'My custom value: ' . $value; } ); // Set fixed value $transformer->set('bar.0.item', 'default-value'); // Apply transformation to array item $transformer->rule()->transform( function (ArrayTransformer $transformer) { $transformer ->map('id', 'id', 'integer') ->map('first_name', 'first_name', 'string'); } ); // Apply transformation to a list of arrays $transformer->rule()->transformList( function (ArrayTransformer $transformer) { $transformer ->map('id', 'id', 'integer') ->map('first_name', 'first_name', 'string'); } );
Custom Filter
You can also add your own custom filter:
$transformer = new ArrayTransformer(); // Add a trim filter using the native trim function $transformer->registerFilter('trim', 'trim'); // Usage $transformer->map('destination', 'source', 'trim'); // or $transformer->map('destination', 'source', $transformer->rule()->filter('trim'));
Add a custom filter using a callback:
$transformer = new ArrayTransformer(); $transformer->registerFilter( 'custom1', function ($value) { return 'Custom value: ' . $value; } ); // Usage $transformer->map('destination', 'source', 'custom1'); // or $transformer->map('destination', 'source', $transformer->rule()->filter('custom1')); // It is possible to chain multiple filters $transformer->map( 'destination', 'source', $transformer->rule()->filter('custom1')->filter('trim')->required()->default('example') );
Define a custom filter using a mapping specific callback:
$transformer = new ArrayTransformer(); $transformer->map( 'destination', 'source', $transformer->rule()->callback( function ($value) { return 'Callback value: ' . $value; } ) );
There are even more filter classes available that can be registered manually:
use Selective\Transformer\Filter\SprintfFilter; $transformer = new ArrayTransformer(); // Convert the value using the sprintf function $transformer->registerFilter('sprintf', new SprintfFilter()); // Usage $transformer->map('destination', 'source', $transformer->rule()->filter('sprintf', 'Count: %d'));
You can also implement and register your own filter classes as well.
Examples
JSON conversion
You can use your own json component or just the native json_encode function.
// Turn all of that into a JSON string $json = (string)json_encode($transformer->toArray($data));
Writing JSON to a PSR-7 response object:
// Set correct header $response = $response->withHeader('Content-Type', 'application/json'); // Write json string to the response body $response->getBody()->write($json); return $response;
PDO resultset conversion
use Selective\Transformer\ArrayTransformer; $pdo = new PDO($dsn, $username, $password, $options); $statement = $pdo->query('SELECT id, username, first_name FROM users'); $rows = $statement->fetchAll(); $transformer = new ArrayTransformer(); $transformer->map('id', 'id', 'integer') ->map('username', 'username', 'string|required') ->map('first_name', 'first_name', 'string|required'); $result = $transformer->toArrays($rows);
The result:
[
[
'id' => 1,
'username' => 'sally',
'first_name' => 'Sally',
]
// ...
];
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License
The MIT License (MIT). Please see License File for more information.