Decoding Laravel Validation : $this->validate()Jul 31, 2017
Recently, while working on one of my project, I was wondering how laravel
$this->validate() works under the hood. So I decided to dig deep into laravel core to find its implementation. Upon finding, it persuaded me to start a series called “Decoding Laravel”. So from now on, I’m planning to publish once in a while explaining about core functionalities of laravel. Today, we are going to decode laravel validation ($this->validate()) method. I’m using laravel 5.4 for this article.
In order to understand its implementation, first we need to know what does
$this->validate() do. So lets start with its function definition on
Illuminate\Foundation\Validation\ValidatesRequests trait file. You can see this trait being imported and used on
App\Http\Controllers\Controller file so that you can access it with
It has four parameters.
- The Request object
- List of rules for validation
- List of custom errors messages if any.
- List of custom attributes (To know more about custom attributes implementation, check this stackoverflow answer)
Now inside, you can see it calls the
getValidationFactory() method. So lets go to its definition on same file.
getValidationFactory() returns the instance of contract class
Illuminate\Contracts\Validation\Factory which is binded with laravel’s Validation Factory class on
Illuminate\Foundation\Application the core file.
getValidationFactory() it calls
make() method. Which is nothing but calling the original
$this->validate() is nice wrapper around the
Now, if validation passes, it doesn’t do anything but if it fails, it throws Exception
Here, you can see it throws
Illuminate\Validation\ValidationException exception after calling the
buildFailedValidationResponse method and this is passed with request object and list of errors that is returned from
On buildFailedValidationResponse method, it is generates failed validation response along with Redirect URL, Old inputs and Error messages.
ValidationException class on
Illuminate\Validation accepts two params on construct method, validator instance and redirect response instance that is returned from buildFailedValidationResponse
Now thrown exception is caught and handled by laravel’s Handler class on
Here you can see it checks for ValidationException and returns the response from
This method checks whether the response variable on ValidationException has any value(in our case we already have redirect response stored on response variable), if so, it simply returns it. If not, it fetches the error messages and returns the redirect response accordingly.
This is how laravel validation using
$this->validate() method works.