我有一个帖子表，可以是视频帖子，文本帖子或图片帖子，以及一个帖子属于一个组。我认为多态关系是正确的方法，但我的表看起来有点奇怪。
我的帖子表：
+---------------+------------------+------+-----+---------------------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------------+------------------+------+-----+---------------------+----------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| postable_id | int(10) unsigned | NO | | NULL | |
| postable_type | varchar(255) | NO | | NULL | |
| group_id | int(10) unsigned | NO | MUL | NULL | |
| upvotes | int(10) unsigned | NO | | 0 | |
| downvotes | int(10) unsigned | NO | | 0 | |
| created_at | timestamp | NO | | 0000-00-00 00:00:00 | |
| updated_at | timestamp | NO | | 0000-00-00 00:00:00 | |
+---------------+------------------+------+-----+---------------------+----------------+
text_posts表：
+------------+------------------+------+-----+---------------------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+------------------+------+-----+---------------------+----------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| title | varchar(130) | NO | | NULL | |
| body | text | NO | | NULL | |
| created_at | timestamp | NO | | 0000-00-00 00:00:00 | |
| updated_at | timestamp | NO | | 0000-00-00 00:00:00 | |
+------------+------------------+------+-----+---------------------+----------------+
video_posts表：
+------------+------------------+------+-----+---------------------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+------------------+------+-----+---------------------+----------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| title | varchar(130) | NO | | NULL | |
| path | varchar(255) | NO | | NULL | |
| body | varchar(255) | YES | | NULL | |
| created_at | timestamp | NO | | 0000-00-00 00:00:00 | |
| updated_at | timestamp | NO | | 0000-00-00 00:00:00 | |
+------------+------------------+------+-----+---------------------+----------------+
picture_posts表：
+-------------+------------------+------+-----+---------------------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+------------------+------+-----+---------------------+----------------+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| path | varchar(255) | NO | | NULL | |
| body | varchar(255) | YES | | NULL | |
| is_external | tinyint(1) | NO | | NULL | |
| created_at | timestamp | NO | | 0000-00-00 00:00:00 | |
| updated_at | timestamp | NO | | 0000-00-00 00:00:00 | |
+-------------+------------------+------+-----+---------------------+----------------+
我看了laravel.com的例子。它指出“多态关系允许模型属于多个其他模型，在一个关联上。”但在这种情况下，我的“帖子”不应属于“视频帖子”或“文本帖子”等。视频帖子等应该属于“帖子”。我怎样才能改进我的表？
答案 0 :(得分：1)
Many To Many多态关系：根据您的表格，您的公共表格是posts，您希望在其他三个不同的实体（表格）之间建立关系，换句话说，就是所有三个表格（texts，videos并且pictures）将共享posts表，例如，您有三个这样的表（每个表id为Primary Key）：
texts table |
videos table |--- posts
pictures table |
每个表都应与posts表相关联，因此您需要三个单独的表，每个表需要三个模型;
Table | Other Personal Fields | Model
------------------------------------------------------------
texts (with id PK) | title, body | Text
videos (with id PK) | title, path, body | Video
pictures (with id PK) | path, body, is_external | Picture
主/公用表为posts，将所有常用字段放在此表中：
id (PK) |
group_id |
upvotes |--- These are common/sharable fields by other three models
downvotes |
created_at |
updated_at |
postables与所有其他人（文字，视频和图片）之间关系的第四张表POST：
post_id | Always id of posts table
| These two fields will build relation
postable_id | id of texts or videos or pictures
postable_type | The model/type: Text/Video/Picture
与Post相对的三个模型：
// Text: In the postables table postable_id
// will be texts_id and type will be Text for text_post
class Text extends Eloquent {
public function posts()
{
return $this->morphToMany('Post', 'postable');
}
}
// Video: in the postables table postable_id will
// be videos_id and type will be Video for video_post
class Video extends Eloquent {
public function posts()
{
return $this->morphToMany('Post', 'postable');
}
}
// Picture: in the postables table postable_id will
// be pictures_id and type will be Picture for picture_post
class Picture extends Eloquent {
public function posts()
{
return $this->morphToMany('Post', 'postable');
}
}
Post型号：
class Post extends Eloquent {
public function texts()
{
return $this->morphedByMany('Text', 'postable');
}
public function videos()
{
return $this->morphedByMany('Video', 'postable');
}
public function pictures()
{
return $this->morphedByMany('Picture', 'postable');
}
}
在postables表数据中可能是这样的：
post_id | postable_id | postable_type
---------------------------------------
1 | 1 | Text // In postable_id 1 is id of texts table
1 | 1 | Video // In postable_id 1 is id of videos table
1 | 1 | Picture // In postable_id 1 is id of pictueres table
2 | 3 | Text // In postable_id 3 is id of texts table
用法：
$post = Post::find(1);
$postsHastTextPosts = $post->texts();
反向使用（Text）：
$text = Text::find(1);
$text->posts()->first()->group_id;
$text->posts()->first()->upvotes;
反向使用（Video）：
$vdo = Video::find(1);
$vdo->posts()->first()->group_id;
$vdo->posts()->first()->upvotes;
反向使用（Picture）：
$picture = Picture::find(1);
$picture->posts()->first()->group_id;
$picture->posts()->first()->upvotes;
这可以使用many to many多态关系来完成。所有三个模型（Text，Video和Picture）都可以共享相同的公共POST属性，意味着在一个组（group_id）中所有三种类型的模型都属于。< / p>
在此many-to-many polymorphic关系中，使用一个表格（postables），三个pivot个表post_text，post_picture和post_video排除。