无法注册用户 - photo_id没有默认值（版本5.6）

Question

我创建了我的用户和照片表。现在我已将photo_id添加到我的users表中，我无法注册用户，并且它给出了一个错误，指出photo_id没有默认值。

这是我的用户模型：

<?php
namespace App;
use Illuminate\Notifications\Notifiable;
use Illuminate\Foundation\Auth\User as Authenticatable;
class User extends Authenticatable
{
    use Notifiable;
    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'name', 'email', 'password','photo_id'
    ];
    public function photo(){
        return $this->belongsTo('App\Photo');
    }
    /**
     * The attributes that should be hidden for arrays.
     *
     * @var array
     */
    protected $hidden = [
        'password', 'remember_token',
    ];
}

照片模型：

<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class Photo extends Model
{
    //
    protected $fillable = ['path'];
}

用户迁移表

class CreateUsersTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('users', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('photo_id');
            $table->string('name');
            $table->string('email')->unique();
            $table->string('password');
            $table->rememberToken();
            $table->timestamps();
        });
    }
    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('users');
    }
}

这是我的照片迁移

<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreatePhotosTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('photos', function (Blueprint $table) {
            $table->increments('id');
            $table->string('path');
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('photos');
    }
}

这是我在尝试注册用户时看到的内容：