Transformer

A simple way to transform data, with helpers for transforming data in Laravel applications.

Installation

• Install Transformer using composer: composer require konsulting/laravel-transformer

Transformer in a Laravel application

• Transformer uses Illuminate\Support\Collection and Illuminate\Support\Arr, and requires a couple of extensions to these. The extensions are available in the konsulting/laravel-extend-collections package.
• You'll need both the CollectionsServiceProvider from that package, and TransformerServiceProvider in your config/app.php.

If you are using Laravel 5.5, they will auto-register. However, if you have chosen not to auto-register, or are using an earlier version, add the following to config/app.php

'providers' => [
    // Other service providers...

    Konsulting\Laravel\CollectionsServiceProvider::class,
    Konsulting\Laravel\Transformer\TransformerServiceProvider::class,
],

• Optionally, add the Transformer Facade to config/app.php

'aliases' => [
    // Other aliases...

    'Transformer' => Konsulting\Laravel\Transformer\TransformerFacade::class,
],

• Optionally publish the config file, and adjust the rule packs you want to use. php artisan vendor:publish --provider=Konsulting\\Laravel\\Transformer\\TransformerServiceProvider --tag=config

Transformer outside a Laravel application

• Transformer uses Illuminate\Support\Collection and Illuminate\Support\Arr. Outside a Laravel application, it will use tighten/collect (an extraction of Collection && Arr from Laravel's Illuminate\Support) to get these dependencies.
• Transform also requires a couple of extensions to these. The extensions are available in the konsulting/laravel-extend-collections package. You'll need to register the extensions manually.
• You will need to build up your Transformer manually for use in your application.

    // Basic example

    use Konsulting\Laravel\Transformer\Transformer;
    use Konsulting\Laravel\Transformer\RulePacks\CoreRulePack;
    use Konsulting\Laravel\Transformer\RulePacks\CarbonRulePack;

    require __DIR__ . '/../vendor/autoload.php';

    // Extend Illuminate\Support\Arr and Illuminate\Support\Collection
    \Konsulting\Laravel\load_collection_extensions();

    // Build up Transformer
    $transformer = new Transformer([CoreRulePack::class, CarbonRulePack::class]);

    // Transformer now available to use, see Usage

Usage

Transformer uses RulePacks to provide transformation functionality. RulePacks can be added to the Transformer during construction, or after with the addRulePack or addRulePacks methods.

A set of rules can be passed in during construction (useful when applying the same rules to different sets of data) or rules can be passed in at the point when performing transformation.

To transform data, the transform method is used. It accepts an array (or collection) of data to transform, and optionally rules to apply.

• Rules are presented in a similar manner to the Laravel Validator. They provide functionality to handle nested data, and follow the same string format.
• Arrays of rules are indexed by a field expression and provide a | (pipe) delimited list of rules to apply.
• Rules may be provided a set of parameters in CSV format. Field expressions may use * as a wildcard to match elements at that depth and ** as a special case to match everything.
• Rule sequences are built up in the order they are provided.

    // using the $transformer built up earlier

    $rules = [
        '*' => 'drop_if_empty',
        'name' => 'trim',
        'contacts.*.name' => 'trim|uppercase'
    ];

    $data = [
        0 => '',
        'name' => '   Keoghan Litchfield   ',
        'contacts' => [
            ['name' => 'Robin'],
            ['name' => 'Roger'],
            ['name' => ''],
        ],
    ];

    $result = $transformer->transform($data, $rules);

    //    Outputs [
    //        'name' => 'Keoghan Litchfield',
    //        'contacts' => [
    //            ['name' => 'ROBIN'],
    //            ['name' => 'ROGER'],
    //        ],
    //    ];

Transform helper

There is also a helper class Transform, which facilitates the easy transformation of a single value by one or more rules. Transform receives an instance of Transformer via its constructor, which provides the transformation logic and determines which rules are available. Using the instance of Transformer built up previously:

use Konsulting\Laravel\Transformer\Transform;

$transform = new Transform($transformer);

Rules may be called as methods on the Transform object, with the value to be transformed passed in as the first argument and any rule parameters as subsequent arguments.

$transform->trim(' Some string to be trimmed   ');  // Outputs 'Some string to be trimmed'

$transform->regexReplace('testing', 'e', 'oa');     // Outputs 'toasting'

Alternatively, rules may be passed via the withRule() and withRules() methods (for singular and multiple rules respectively). Rule parameters are passed either as separate arguments, or as an array.

// Single rule
$transform->withRule('  test  ', 'trim');                           // Outputs 'test'

// Single rule with parameters passed as separate arguments
$transform->withRule('test', 'regex_replace', 'e', 'oa');           // Outputs 'toast'

// Singe rule with parameters passed as an array
$transform->withRule('test', 'regex_replace', ['e', 'oa']);         // Outputs 'toast' as well

// Multiple rules passed as a sequential array
$transform->withRules('  test  ', ['trim', 'uppercase']);           // Outputs 'TEST'

// Multiple rules and parameters passed as an assocative array: [$rule => [$param1, $param2], $rule2 => []...]
$transform->withRules('--test--', [                                 // Outputs 'TOAST'
    'trim'          => ['-'],
    'regex_replace' => ['e', 'oa'],
    'uppercase'     => [],
]);

Fluent API

Rules may also be called fluently: the input value is set with the input() method, and the result is obtained with get(). Any number of rule methods may be chained between these.

$transform->input(' hello ')
    ->trim()
    ->regexReplace('hello', 'world')
    ->uppercase()
    ->get();

// Outputs 'WORLD'

When the fluent API is used, the value is not passed as an argument to the rule methods (as it has already been set via input()). As such, all arguments passed to rule methods are treated as rule parameters.

withRule() and withRules() may be used to fluently declare rules with or without parameters:

$transform->input($input)
    ->withRule('trim')
    ->uppercase()
    ->get();

$transform->input($input)
    ->lowercase()
    ->withRules(['trim', 'uppercase'])
    ->get();

Available Rules

We provide a couple of rule packs for use, it is easy to extend the rules available by creating your own Rule Pack. Rule Packs are loaded in the declared order, methods in later packs will override packs loaded earlier.

Parameter names are denoted by <param> and optional parameters by [<param>].

Core Rule Pack

Cleaning up

• null_if_empty
• null_if_empty_string
• return_null_if_empty – equivalent to null_if_empty|bail_if_null.
• return_null_if_empty_string – equivalent to null_if_empty_string|bail_if_null.
• bail_if_null
• drop_if_null
• drop_if_empty
• drop_if_empty_string
• trim:[<character(s)_to_trim>] – performs default PHP trim() if no characters supplied.

Casting

• string - convert to string, an array is transformed to a CSV or returns ‘’ for items that cannot be represented as a string.
• boolean
• array
• collection - convert to Illuminate\Support\Collection
• json
• float
• integer
• date_time:[timezone]
• date_time_immutable:[timezone]

String manipulation

• uppercase
• lowercase

Regex and string replace

• replace:<search_string>,<replace_string>
• regex_replace:<search_regex>,<replace_string>
• numeric
• alpha
• alpha_dash
• alpha_num
• alpha_num_dash

Carbon Rule Pack

• carbon
• date_format - parameter for the format required.

Related Fields Rule Pack

• null_with:<key>
• drop_with:<key>
• bail_with:<key>
• null_without:<key>
• drop without:<key>
• bail_without:<key>

Number Rule Pack

• clamp:<min>,<max> - constrain a number between two values

Note: key is a dot notation key for another field in the dataset

Laravel Helpers

We use Laravel frequently, so have a couple of extras added here.

Facade

Use the facade to gain easy access to the Transformer wherever you are.

\Transformer::transform($data, $rules);

Request Macro transform

The Service Provider adds the transform Macro to the Illuminate\Http\Request class. This makes it simple to invoke the transformation on a request at any point. The method passes the request object back to allow chaining.

// Example Controller

namespace App\Http\Controllers;

use App\ContactRequest;
use Illuminate\Http\Request;

class ContactRequestsController
{
    // ...

    public function store(Request $request)
    {
        $request->transform([
            'name' => 'trim|uppercase',
            'message' => 'trim',
        ]);

        $this->validate($request, [
            'name' => 'required',
        ]);

        return ContactRequest::create(
            $request->only('name', 'message')
        );
    }
}

TransformingRequest Trait

This trait makes the form request transform the data before validation occurs (which is upon it being resolved by the container).

Rules for transformation are provided in the transformRules method.

Using the TransformingRequest Trait

// Form Request

namespace App\Http\Requests;

use Illuminate\Foundation\Http\FormRequest;
use Konsulting\Laravel\Transformer\TransformingRequest;

class ContactFormRequest extends FormRequest
{
    use TransformingRequest;

	  // ... other methods including rules()

    public function transformRules()
    {
        return [
            'name' => 'trim|uppercase',
            'message' => 'trim',
        ];
    }

// Controller

namespace App\Http\Controllers;

use App\ContactRequest;
use App\Http\Requests\ContactFormRequests;

class ContactRequestsController
{
    // ...

    public function store(ContactFormRequest $request)
    {
        return ContactRequest::create(
            $request->only('name', 'message')
        );
    }
}

Middleware

The TransformRequest middleware applies transformations to requests according to configured rules. These rules are specified in the middleware_rules key of the config file as detailed in Usage.

To register the middleware for use in your project, add the following line to your project's App/Http/Kernel.php:

'transform_data' => \Konsulting\Laravel\Transformer\Middleware\TransformRequest::class

The default middleware rules state that every field should be trimmed of whitespace and nulled if empty:

'middleware_rules' => [
    '**' => 'trim|return_null_if_empty',
]

Rules need not be applied to all fields; specific fields may be targeted within the middleware if required:

'middleware_rules' => [
    'postcode'  => 'uppercase',
    'email'     => 'lowercase',
]

With the above configuration, the postcode and email fields of every request sent through the middleware will be affected, but all other fields will be left unchanged.

Multiple transformer middlewares may be useful in a project: to achieve this, copy laravel-transformer/src/Middleware/TransformRequest.php to your project's App/Http/Middleware directory, and rename/edit as necessary. Each new middleware will have to be registered in the kernel.

Contributing

Contributions are welcome and will be fully credited. We will accept contributions by Pull Request.

Please:

• Use the PSR-2 Coding Standard.
• Add tests, if you’re not sure how, please ask.
• Document changes in behaviour, including readme.md.

Testing

We use PHPUnit and the excellent orchestral/testbench.

Run tests using PHPUnit: vendor/bin/phpunit