laravel sql error: SQLSTATE [HY000]: General error: 1364 Field 'user_id' does not have a default value

SQLSTATE [HY000]: General error: 1364 Field 'user_id' does not have a default value (SQL: insert into `tasks` (`status`, `content`, `updated_at`, `created_at`)

<?php
namespace App;
use Illuminate\Database\Eloquent\Model;

class Task extensions Model
{
    protected$fillable=['content', 'status', 'user_id'];

    public function user()
    {
        return$this->belongsTo(User::class);
    }
}

<?php
namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Task;

class TasksController extensions Controller
{
    /**
     * Display a listing of the resource.
     *
     * @return\Illuminate\Http\Response
     */
    public function index()
    {
        $data=[];
        if(\Auth::check()){
            $user=\Auth::user();
            $tasks=$user->tasks()->orderBy('created_at','desc')>paginate(10);

            $data=[
                'user' = > $user,
                'tasks' = > $tasks,
            ];

            return view('tasks.index',[
                'tasks' = > $tasks,
            ]);

        } else{
            return view('welcome');    
        }

    }

    /**
     * Show the form for creating a new resource.
     *
     * @return\Illuminate\Http\Response
     */
    public function create()
    {
        $task = new Task;

        return view('tasks.create',[
            'task' = > $task,
        ]);
    }

    /**
     * Store a newly created resource in storage.
     *
     * @param\Illuminate\Http\Request$request
     * @return\Illuminate\Http\Response
     */
    public function store(Request$request)
    {

        $this->validate($request,[
            'status' = > 'required | max:10',
            'content' = > 'required | max:191',
        ]);

        $task = new Task;
        $task->status=$request->status;
        $task->content=$request->content;
        $task->save();

        return redirect('/');
    }

    /**
     * Display the specified resource.
     *
     * @param int$id
     * @return\Illuminate\Http\Response
     */
    public function show($id)
    {
        $task=Task::find($id);

        return view('tasks.show',[
            'task' = > $task,
        ]);
    }

    /**
     * Show the form for editing the specified resource.
     *
     * @param int$id
     * @return\Illuminate\Http\Response
     */
    public function edit($id)
    {
        $task=Task::find($id);

        return view('tasks.edit',[
            'task' = > $task,
        ]);
    }

    /**
     * Update the specified resource in storage.
     *
     * @param\Illuminate\Http\Request$request
     * @param int$id
     * @return\Illuminate\Http\Response
     */
    public function update(Request$request,$id)
    {

        $this->validate($request,[
            'status' = > 'required | max:10',
            'content' = > 'required | max:191',
        ]);

        $task=Task::find($id);
        $task->status=$request->status;
        $task->content=$request->content;
        $task->save();

        return redirect('/');
    }

    /**
     * Remove the specified resource from storage.
     *
     * @param int$id
     * @return\Illuminate\Http\Response
     */
    public function destroy($id)
    {
        $task=Task::find($id);
        $task->delete();

        return redirect('/');
    }
}