Laravel hasMany 和belongsTo 参数

2021-12-26 00:00:00 php mysql laravel eloquent

我有一个表存储，存储有很多库，在库中我有存储store_id的外键.

I have a table store, and store has many libraries, in library I have foreign key of store store_id.

存储表

id(PK)

图书馆表

id(PK)
store_id(FK)

我对 hasMany 和 belongsTo 参数感到困惑，包括在 docs 它说

I'm confused with hasMany and belongsTo parameters include, in the docs it says

return $this->hasMany('AppComment', 'foreign_key');

return $this->hasMany('AppComment', 'foreign_key');

return $this->hasMany('AppComment', 'foreign_key', 'local_key');

return $this->hasMany('AppComment', 'foreign_key', 'local_key');

return $this->belongsTo('AppPost', 'foreign_key', 'other_key');

return $this->belongsTo('AppPost', 'foreign_key', 'other_key');

hasMany foreign_key 和 local_key 来自哪个表?和belongsTo一样，foreign_key和other_key是从哪个表来的?

Which table of hasMany foreign_key and local_key came from? Same with belongsTo which table of foreign_key and other_key came from?

店铺模式

public function library(){
    return $this->hasMany('AppLibrary', 'what_foreign_key_should_be_here','what_other_key_should_be_here');
}

图书馆模型

public function stores(){
    return $this->belongsTo('AppStores', 'what_foreign_key_should_be_here', 'what_other_key_should_be_here');
}

因为有时候我把一个表的主键id改成sid这样的其他名字，所以我总是想指定哪个是外键和主键

Because sometimes I change my primary key id of a table to other name like sid, so I always want to specify which is foreign key and primary key

推荐答案

为了简化语法，想到了 return $this->hasMany('AppComment', 'foreign_key', 'local_key'); 参数为:

To simplify the syntax, think of the return $this->hasMany('AppComment', 'foreign_key', 'local_key'); parameters as:

  1. 您要链接到的模型
  2. 链接回当前表的 id 列的外部表(您要链接到的表)的列(除非您指定了第三个参数，在这种情况下它将使用那个)
  3. 应该使用的当前表的列 - 即如果您不希望其他表的外键链接到当前表的 id 列
  1. The model you want to link to
  2. The column of the foreign table (the table you are linking to) that links back to the id column of the current table (unless you are specifying the third parameter, in which case it will use that)
  3. The column of the current table that should be used - i.e if you don't want the foreign key of the other table to link to the id column of the current table

在您的情况下，因为您在 libraries 表中使用了 store_id，您的生活变得轻松了.在您的 Store 模型中定义时，以下内容应该可以完美运行:

In your circumstance, because you have used store_id in the libraries table, you've made life easy for yourself. The below should work perfectly when defined in your Store model:

public function libraries()
{
    return $this->hasMany('AppLibrary');
}

在幕后，Laravel 会自动将Store 表的id 列链接到Library<的store_id 列/code> 表格.

Behind the scenes, Laravel will automatically link the id column of the Store table to the store_id column of the Library table.

如果你想明确定义它，那么你可以这样做:

If you wanted to explicitly define it, then you would do it like this:

public function libraries(){
    return $this->hasMany('AppLibrary', 'store_id','id');
}

  • 模型标准是单数命名的函数返回一个belongsTo，而复数函数返回一个hasMany(即$store->libraries() 或$library->store()).

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