Presenters/Unpresenters Framework
Presenters are often used to convert data in a storage format for display. Typical implementations use the decorator pattern., (*1)
A similar problem exists when receiving information back from a user, for example on a web form. This needs to be
converted from a human readable format into a format suitable for storage., (*2)
This is an Unpresenter., (*3)
This implementation provides four core capabilities, (*4)
- Automatically handles date conversion from a defined format into a Carbon instance for storage
- Automatically handles checkboxes from forms (not nested)
- Handles validation simply
- Provides facility to mutate any attribute.
Requirements
- Laravel
- As for Laravel >= v4.1
Installation
You must install this library through Composer:, (*5)
{
"require": {
"SauveSolutions/presenters": "0.2.*"
}
}
Usage
Using the library is very simple., (*6)
- Derive an unpresenter class from SauveSolutions\presenters\Unpresenter and implement the functionality you need, typically
this is just listing the date variables, the checkbox variables and the validation rules.
- In a controller instantiate an instance of the Unpresenter and pass the input array to the constructor.
- Call validate and trap any ValidationExceptions thrown.
- Access input variables directly from the unpresenter instance.
class ExampleUnpresenter extends SauveSolutions\presenters\Unpresenter {
//specify any date fields
protected $dates = ['a_date'];
//specify any checkboxes that may be expected in the data sent with the web request
protected $checkboxes = ['important'];
/**
* Specify the validation rules to be applied.
*
* @param $bUpdate boolean Pass true if the object is being updated, false otherwise.
* @return array The validation rules.
*/
public function getValidationRules($update) {
//if updating an existing record then $update would be true, for a new record it would be false. This allows you
//to create different rules for updates to existing records or creation of new records, e.g. unique checks that exclude the current record.
//for this example however simply use a single response.
return array(
'a_date' => 'date_format:d/m/Y'
);
}
}
Then in your controller method, for example Store., (*7)
public function store() {
$input = Input::except('_token', '_method');
$input = new ExampleUnpresenter($input);
//simple try/catch block - the exception could be caught globally if preferred.
try {
//now try and validate
$input->validate(false);
} catch (SauveSolutions\exceptions\ValidationException $e) {
//if it failed then redirect back.
return Redirect::route('example.create')->withInput()->withErrors($e->getValidationErrors());
}
//now create a new example model.
$model = new ExampleModel();
$model->a_date = $input['a_date'];
$model->save();
//and finally let's show the index page.
return Redirect::route('example.index');
}
Alternative
An alternative is to call $unpresenter->parseInput() which processes all of the input data and returns a plain php array
of the transformed inputs., (*8)
FAQ
The DateConverter trait uses an English locale date format (d/m/Y) how can I change this? The simplest approach would be
to derive your own Unpresenter class which overrides DateConverter::getDateFormat(). It is expected in any non trivial application
that the date format is an attribute of the User or a similar global setting. Then use your Unpresenter class as the base class
of any other Unpresenters you create., (*9)
Laravel 4.3
Laravel 4.3 has implemented a new FormRequest object that performs the validation functionality of the Unpresenter class. Together with the
ability to resolve a class from a hint on a controller method out of the IoC container will provide a further productivity boost.
It is likely that the Unpresenter functionality can be combined with the FormRequest functionality in a subclass to provide the
transformation capbility. This will be investigated in a future update., (*10)
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