How to prevent duplicate values being posted?

Question

I have a code that posts details from a form that looks like this. Field that contains Ampang, Kuala Lumpur = area_slug

This form then goes into a controller that as a post function to save the values in a table. Below is the code in the post function:

        if ( $this->outlet->locations->count() ) {
            foreach ( $this->outlet->locations as $index => $location ) {

                $area = Level2::find( $locations[ $index ][ 'area_id' ] );
                $area_slug = ( $area ? $area->slug : '' );
                $shipping_fee_value = (float)$locations[ $index ][ 'shipping_fee_value' ];

                // two type of conditional checks
                // $shipping_fee_allow_negotiate = !empty( $location[ 'shipping_fee_allow_negotiate' ] );
                if ( !empty( $locations[ $index ][ 'shipping_fee_allow_negotiate' ] ) ) {
                    $shipping_fee_allow_negotiate = 1;
                } else {
                    $shipping_fee_allow_negotiate = 0;
                }

                /**
                 * Update each location belongs to Outlet
                 * Laravel Model Insert
                 * @see https://laravel.com/docs/8.x/eloquent#updates
                 */
                $location->area_slug = $area_slug;
                $location->shipping_fee_value = $shipping_fee_value;
                $location->shipping_fee_allow_negotiate = $shipping_fee_allow_negotiate;
                $location->update();
            }
        } else {
            foreach ( $locations as $location ) {

                $area = Level2::find( $location[ 'area_id' ] );
                $area_slug = ( $area ? $area->slug : '' );
                $shipping_fee_value = (float)$location[ 'shipping_fee_value' ];

                // two type of conditional checks
                // $shipping_fee_allow_negotiate = !empty( $location[ 'shipping_fee_allow_negotiate' ] );
                if ( !empty( $location[ 'shipping_fee_allow_negotiate' ] ) ) {
                    $shipping_fee_allow_negotiate = 1;
                } else {
                    $shipping_fee_allow_negotiate = 0;
                }

                /**
                 * Create Location and related it to Outlet with `outlet_id`
                 * Laravel Model Insert
                 * @see https://laravel.com/docs/8.x/eloquent#inserts
                 */
                $location = new Location();
                $location->outlet_id = $this->outlet->id;
                $location->area_slug = $area_slug;
                $location->shipping_fee_value = $shipping_fee_value;
                $location->shipping_fee_allow_negotiate = $shipping_fee_allow_negotiate;
                $location->save();
            }
        }

So what I'm trying to achieve is to prevent the same area_slug being posted eg. Ampang, Kuala Lumpur in both Location 1 and Location 2 respective fields. I have the idea of getting the previous area_slug but I'm not sure how to do so. If there are any unclear details do comment.

Answer 1

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();

Answer 2

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

Answer 3

If you're using Laravel's validation, you can use distinct to ensure uniqueness over all submitted locations:

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