failed POST request in postman with Laravel 5.7

I am using postman to send post request as json file to the tasks table. this is My api.php route

Route::post('/tasks', 'TaskController@create'); 

and TaskController

public function create(Request $request)
    {
        $rules = [
            'name' => 'required',

            'owner' => 'required'
        ];

        $validate = Validator::make($request->all(), $rules);
        if ($validate->fails()) {
            return $validate->errors();
        }

        return Task::create([
            'name' => $request->title,

            'owner' => $request->status
        ]);
    }

and I have following url in postman http://localhost:8000/api/tasks with POST request and under the ‘Body’ tab choose the ‘raw’ radio button and then ‘JSON (application/json)’ from the drop down. and send data body in postman is like this.

{ 
"name": "sara",
"owner": "mala" 
}

but when send data it is not saving to the table and occured following error massage. SQLSTATE[23000]: Integrity constraint violation: 1048 Colum 'name' cannot be null how can fix this problem?

via Chebli Mohamed