laravel validation

use the validate method provided by the Illuminate\Http\Request object. If the validation rules pass, your code will keep executing normally; however, if validation fails, an exception will be thrown and the proper error response will automatically be sent back to the user. In the case of a traditional HTTP request, a redirect response will be generated, while a JSON response will be sent for AJAX requests.

$validatedData = $request->validate([
        'title' => 'required|unique:posts|max:255',
        'body' => 'required',
    ]);

Stopping On First Validation Failure

Sometimes you may wish to stop running validation rules on an attribute after the first validation failure. To do so, assign the bail rule to the attribute:

$request->validate([

    'title' => 'bail|required|unique:posts|max:255',

    'body' => 'required',

]);

If your HTTP request contains "nested" parameters, you may specify them in your validation rules using "dot" syntax:

$request->validate([

    'title' => 'required|unique:posts|max:255',

    'author.name' => 'required',

    'author.description' => 'required',

]);

Displaying The Validation Errors

@if ($errors->any())

    <div class="alert alert-danger">

        <ul>

            @foreach ($errors->all() as $error)

                <li>{{ $error }}</li>

            @endforeach

        </ul>

    </div>

@endif

You may also use the @error Blade directive(form 5.8.13)to quickly check if validation error messages exist for a given attribute. 

<input id="title" type="text" class="@error('title') is-invalid @enderror">

@error('title')

    <div class="alert alert-danger">{{ $message }}</div>

@enderror

Working With Error Messages

$errors = $validator->errors();
echo $errors->first('email');

retrieve an array of all the messages for a given field, use the get method:

foreach ($errors->get('email') as $message) {
    //
}

foreach ($errors->all() as $message) {
    //
}

if ($errors->has('email')) {
    //
}

Manually Creating Validators

If you do not want to use the validate method on the request, you may create a validator instance manually using the Validator facade.

$validator = Validator::make($request->all(), [

            'title' => 'required|unique:posts|max:255',

            'body' => 'required',

        ]);

if ($validator->fails()) {

            return redirect('post/create')

                        ->withErrors($validator)

                        ->withInput();

        }

If you would like to create a validator instance manually but still take advantage of the automatic redirection offered by the requests's validate method, you may call the validate method on an existing validator instance. If validation fails, the user will automatically be redirected or, in the case of an AJAX request, a JSON response will be returned:

Validator::make($request->all(), [
    'title' => 'required|unique:posts|max:255',
    'body' => 'required',
])->validate();

Custom Error Messages

$messages = [

    'email.required' => 'We need to know your e-mail address!',

];

$validator = Validator::make($input, $rules, $messages);

Validating When Present

email field will only be validated if it is present in the $data array.

$v = Validator::make($data, [

    'email' => 'sometimes|required|email',

]);

$v = Validator::make($data, [

    'email' => 'required|email',

    'games' => 'required|numeric',

]);

$v->sometimes('reason', 'required|max:500', function ($input) {

    return $input->games >= 100;

});

The first argument passed to the sometimes method is the name of the field we are conditionally validating. The second argument is the rules we want to add. If the Closure passed as the third argument returns true, the rules will be added.

A Note On Optional Fields

By default, Laravel includes the TrimStrings and ConvertEmptyStringsToNull middleware in your application's global middleware stack. These middleware are listed in the stack by the  App\Http\Kernel class. Because of this, you will often need to mark your "optional" request fields as nullable if you do not want the validator to consider null values as invalid.