完整性约束违规:1452无法添加或更新子行:外键约束失败(Laravel应用程序)
问题描述:
我在我的laravel应用程序中遇到此错误。完整性约束违规:1452无法添加或更新子行:外键约束失败(Laravel应用程序)
这些都是表:
后
Schema::create('posts', function (Blueprint $table) {
$table->increments('id');
$table->string('title');
$table->text('content');
$table->timestamps();
$table->integer('user_id')->unsigned();
});
分类
Schema::create('categories', function (Blueprint $table) {
$table->increments('id');
$table->string('name');
$table->timestamps();
});
Post_Category
Schema::create('post_category', function (Blueprint $table) {
$table->integer('post_id')->unsigned()->unique()->nullable();
$table->integer('cat_id')->unsigned()->unique()->nullable();
$table->timestamps();
});
外键
Schema::table('posts', function (Blueprint $table) {
$table->foreign('id')->references('post_id')->on('post_category')->onDelete('cascade');
});
Schema::table('categories', function (Blueprint $table) {
$table->foreign('id')->references('cat_id')->on('post_category')->onDelete('cascade');
});
这里我的模型
class Categorie extends Model
{
protected $table = 'categories';
public function posts() {
return $this->hasMany('App\PostCategory');
}
}
...
class Post extends Model
{
public function author() {
return $this->belongsTo('App\User', 'user_id');
}
public function featuredImage() {
return $this->belongsTo('App\Media', 'media_id');
}
public function categories() {
return $this->hasMany('App\PostCategory');
}
}
...
class PostCategory extends Model
{
protected $table = 'post_category';
}
这里控制器
店铺分类:
public function store(StoreCategory $request)
{
$category = new Categorie;
$category->name = $request->input('name');
$category->save();
return redirect('/admin/categories')->with('status', 'New category created!');
}
店后
public function store(StorePost $request)
{
$post = new Post;
$post->title = $request->input('title');
$post->content = $request->input('content');
$post->media_id = $request->input('media_id');
$post->user_id = $request->input('user_id');
$post->save();
return redirect('/admin/posts')->with('status', 'New post created!');
}
有了这个错误
SQLSTATE [2300 0]:完整性约束违规:1452无法添加或更新子行:外键约束失败(
the_film_corner
。tfc_categories
,约束categories_id_foreign
外键(id
)参考文献tfc_post_category
(cat_id
)ON DELETE CASCADE)(SQL:插入tfc_categories
(name
,updated_at
,created_at
)值(新闻,2017年2月26日14时51分15秒,2017-02- 26 14时51分15秒))
感谢
答
你在错误的表添加外键:
Schema::table('post_category', function(Blueprint $table) {
$table->foreign('post_id')->references('id')->on('post')->onDelete('cascade');
$table->foreign('category_id')->references('id')->on('category')->onDelete('cascade');
});
则...
class Categorie extends Model
{
protected $table = 'categories';
public function posts() {
return $this->belongsToMany('App\Category');
// Or more specifically
return $this->belongsToMany('App\Category', 'post_category', 'id', 'post_id');
}
}
class Post extends Model
{
// ...
public function categories() {
return $this->belongsToMany('App\Category');
// Or more specifically
return $this->belongsToMany('App\Category', 'post_category', 'id', 'category_id');
}
}
您可以找到以下官方指南的详细信息:https://laravel.com/docs/5.4/eloquent-relationships#one-to-many
答
错误说明了一切。通过此设置,在将行插入tfc_categories
之前,id
列的值必须存在于表tfc_post_category
的列cat_id
中。如果没有,则违反了失败消息中提到的约束条件。
但我宁愿猜你想要一列来引用另一列,反之亦然。
感谢Samuele的帮助。 –