Laravel 5.1 关系 - SQLSTATE[23000]：违反完整性约束：1452 无法添加或更新子行：外键约束失败

Question

我有 3 个表用户，posts 和评论。 users 和 posts 之间的关系是可以的。我可以存储新的 posts。但是如果我评论 post，我会得到这个错误信息：

错误信息

QueryException in Connection.php line 631: SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (blog.comments, CONSTRAINT comments_post_id_foreign FOREIGN KEY (post_id) REFERENCES posts (id)) (SQL: insert into comments (body, user_id, updated_at, created_at) values (new comment, 1, 2015-07-20 14:16:07, 2015-07-20 14:16:07))

迁移用户

Schema::create('users', function (Blueprint $table) {
        $table->increments('id');
        $table->string('name');
        $table->string('email')->unique();
        $table->string('password', 60);
        $table->rememberToken();
        $table->timestamps();
    });

迁移posts

Schema::create( 'posts', function ( Blueprint $table ) {
        $table->increments( 'id' );
        $table->integer( 'user_id' )->unsigned();
        $table->string( 'title' );
        $table->text( 'body' );
        $table->timestamps();

        $table->foreign( 'user_id' )->references( 'id' )->on( 'users' );
    } );

迁移评论

Schema::create('comments', function (Blueprint $table) {
        $table->increments( 'id' );
        $table->integer( 'user_id' )->unsigned();
        $table->integer( 'post_id' )->unsigned();
        $table->text( 'body' );
        $table->timestamps();

        $table->foreign( 'user_id' )->references( 'id' )->on( 'users' );
        $table->foreign( 'post_id' )->references( 'id' )->on( 'posts' );
    });

模型用户

protected $fillable = [
    'name',
    'email',
    'password'
];

public function posts() {
    return $this->hasMany( 'App\Post' );
}

public function comments() {
    return $this->hasMany( 'App\Comment' );
}

型号Post

protected $fillable = [
    'title',
    'body'
];

public function user() {
    return $this->belongsTo( 'App\User' );
}

public function comments() {
    return $this->hasMany( 'App\Comment' );
}

模特评论

protected $fillable = [
    'body'
];

public function user() {
    return $this->belongsTo( 'App\User' );
}

public function post() {
    return $this->belongsTo( 'App\Post' );
}

评论控制器

public function store( CommentRequest $request ) {
    Auth::user()->comments()->create( $request->all() );
    return redirect()->back();
}

Post控制器$request->all()

"_token" => "TzdItNKU3TChVg50vAqdy1CYCrIR562l4Wv2z6ef"
"title" => "New Post"
"body" => "New text"

CommentController $request->all()

"_token" => "TzdItNKU3TChVg50vAqdy1CYCrIR562l4Wv2z6ef"
"body" => "New Comment"

Answer 1

您的评论模型通过post_id[与Post模型有关系 字段，并且该字段在数据库中为 NOT NULL。因此 table 中的所有记录都需要填写该字段。此外，由于您对该字段有外键约束，它总是需要指向 Post table.

中的现有行

在你的情况下，似乎无论数据传递给你的 Auth::user()->comments()->create()，它都不包含post_id 字段或 post_id 字段未标记为 fillable 评论型号。

我建议您首先检查控制器方法中的 $request->all() returns。如果该字段存在，请将 post_id 添加到 Comment[=30= 中的 fillable 字段列表中] 型号：

protected $fillable = [ /** list all fields that should be fillable by create/update methods **/ ];

Answer 2

我在互联网上发现这个技巧在这种情况下非常有效。

DB::statement('SET FOREIGN_KEY_CHECKS=0;');

Schema::table('foo_products', function(Blueprint $table)
{
    $table->unsignedInteger('foo_type_id');
    $table->foreign('foo_type_id')->references('id')->on('foo_types');
});
DB::statement('SET FOREIGN_KEY_CHECKS=1;');

您只需在模式之前禁用外键检查，然后再启用它。

Laravel 5.1 关系 - SQLSTATE[23000]：违反完整性约束：1452 无法添加或更新子行：外键约束失败

Laravel 5.1 Relationship - SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails

constraints

foreign-keys

relationship

laravel