php - How to prevent duplicate values being posted?

$request->validate([
    '*.location' => 'distinct',
]);

Solution:

I suggest you the following to have a good quality software :

Create a separate request Validation object called ModelStore with the following command :

php artisan make:request ModelStore

use this created as a parameter of your controller store function. like following

public function store(ModelStore $request)

in this ModelStore class implement 2 more function (there is 2 created by default for error code and message)

public function rules()
    {
        return [
            'request_field'  => ['LaravelValidation|anotherLaravelValidation']
        ];
    }

    //In this function you can put all your if else validations and returned a validation array
    public function all($keys = null)
    {
        $data = parent::all($keys);
        $data['one_field'] = affectValue;
        return $data;
    } 

finaly in your controller store function start with this line to have the data array

$validated_data = $request->validated();

And then you have your data validated and cleaned. in the controller you keep only the logic and not validation.

To answer your initial question : if you want to have a complete unique slug field than you simply implement it in the rules with the distinct or unique laravel validation.

Good luck

Solution:

when you creating migration set table field as unique

$table->unique('email');

then you searching use distinct for query

return DB::table('teat_table')
        ->select('teat_table.*')
        ->distinct()
        ->get();