Eloquent ORM / Laravel - 使用自定义数据透视表结构
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Eloquent ORM / Laravel - use custom pivot table structure
提问by Томица Кора?
I'm trying to build a Laravel app using a customized database structure. I have tables types, units, content, and a pivot table called relations. The structure of the relationstable is such:
我正在尝试使用自定义数据库结构构建 Laravel 应用程序。我有表types、units、content和一个名为 的数据透视表relations。relations表的结构是这样的：
---------------------------------------------
| id | relation_type | first_id | second_id |
---------------------------------------------
| 1 | type_unit | 1 | 2 |
---------------------------------------------
| 2 | unit_content | 2 | 3 |
---------------------------------------------
In other words, the first three tables have many-to-many relations among themselves, and the fourth one is the pivot table for all the relations. How can I use the Eloquent's BelongsToManymethod with this pivot table structure, i.e. how can I select only the pivot table's records relevant to the given relation? For example, how would I use only the type_unit relations in this:
换句话说，前三个表之间是多对多的关系，第四个是所有关系的数据透视表。我怎样才能在BelongsToMany这个数据透视表结构中使用 Eloquent 的方法，即我怎样才能只选择与给定关系相关的数据透视表的记录？例如，我将如何仅使用 type_unit 关系：
class Type extends Eloquent {
public function units()
{
return $this->belongsToMany('Unit', 'relations');
}
}
but at the same time ignore the unit_content relations?
但同时忽略了 unit_content 关系？
回答by Umut Sirin
belongsToManywould accept 3rd and 4th arguments. You can see it in documentation: http://laravel.com/docs/eloquent#relationships
belongsToMany将接受第三和第四个参数。您可以在文档中看到它：http: //laravel.com/docs/eloquent#relationships
But the thing that is not in documentation is that you can constraint your relation by chaining the query builder functions like where, orderByetc.
但是，这不是在文档中的事情是，你可以通过链接查询约束你们的关系建设者功能，如where，orderBy等。
So your code would be something like:
所以你的代码会是这样的：
class Type extends Eloquent {
public function units()
{
return $this->belongsToMany('Unit', 'relations', 'first_id', 'second_id')
->withPivot(['relation_type'])
->where('relations.relation_type', '=', 'type_unit');
}
}
