未找到列：1054 在'字段列表'中的未知列'taggables.tags_model_id' laravel eloquent

Question

我打算实现一个查询,以检索我所有的博客和他们的标签. 我使用的是Laravel Eloquent多态关系,但是我有一个错误是 Column not found: 1054 Unknown column 'taggables.tags_model_id' in 'field list'. 我所有的代码在laravel和我的SQL如下。

我的表格。

create table tags
(
    id         int auto_increment
        primary key,
    name       varchar(200)                        null,
    created_at timestamp default CURRENT_TIMESTAMP not null,
    updated_at timestamp                           null,
    deleted_at timestamp                           null
);


create table taggables
(
    id            int auto_increment
        primary key,
    tag_id        int                                 null,
    taggable_type varchar(512)                        null,
    taggable_id   int                                 null,
    created_at    timestamp default CURRENT_TIMESTAMP not null,
    updated_at    timestamp                           null,
    deleted_at    timestamp                           null,
    constraint fk23
        foreign key (tag_id) references tags (id)
            on update cascade on delete cascade
);

create index taggables_tag_id_index
    on taggables (tag_id);


create table blog
(
    id          int auto_increment
        primary key,
    title       varchar(200)                        null,
    passage     text                                null,
    author      varchar(200)                        null,
    category    varchar(200)                        null,
    img_url     varchar(200)                        null,
    created_at  timestamp default CURRENT_TIMESTAMP not null,
    updated_at  timestamp                           null,
    deleted_at  timestamp                           null,
    user_id     int                                 not null,
    category_id int                                 null,
    constraint fk18
        foreign key (user_id) references users (id)
            on update cascade on delete cascade,
    constraint fk19
        foreign key (category_id) references blog (id)
            on update cascade on delete cascade
);

create index blog_index
    on blog (category_id);

create index blog_users_index
    on blog (user_id);

Eloquent Models

class BaseModel extends Model
{
    protected $table;
    protected $primaryKey;


    use SoftDeletes;

}

class BlogModel extends BaseModel
{

    protected $table = 'blog';
    protected $primaryKey = 'id';


    public function tags()
    {
        return $this->morphToMany(TagsModel::class,"taggable");

    }
}


class TagsModel extends BaseModel
{

    protected $table = 'tags';
    protected $primaryKey = 'id';

    public function blog()
    {
        return $this->morphedByMany(BlogModel::class,"taggable");
    }

}

当我调用这个查询时，结果是一个空数组。

 public function getItemsWithTags(array $attr)
    {
        return BlogModel::find(1)->tags;
    }

非常感谢您。

Answer 1

Laravel的多态关系默认使用反射来确定你的关键列的名称. 因为你的模型被称为 TagModel, Laravel假设外键为 tag_model_id.

    // Illuminate\Database\Eloquent\Model
    public function getForeignKey()
    {
        return Str::snake(class_basename($this)).'_'.$this->getKeyName();
    }

你可以通过将正确的外键显式传递给 morphedByMany 方法。

public function tags()
{
    return $this->morphedByMany(TagsModel::class, 'taggable', null, 'tag_id');
}

Answer 2

你不能像BaseModel那样做一个中间的父类. 因为在Laravel中用属性$table是不行的，可以尝试这样做。

class BlogModel extends Model
{
    use SoftDeletes;

    protected $table = 'blog';

    protected $primaryKey = 'id';

    public function tags()
    {
        return $this->morphToMany(TagsModel::class,"taggable");
    }
}


class TagsModel extends Model
{
    use SoftDeletes;

    protected $table = 'tags';

    protected $primaryKey = 'id';

    public function blog()
    {
        return $this->morphedByMany(BlogModel::class,"taggable");
    }
}

Answer 3

试试这个例子, 你需要在你的口才方法中引用 "标签".

BlogModel::with('tags')->find(1);