Laravel Eloquent：急切加载多个嵌套关系
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Laravel Eloquent: eager loading of multiple nested relationships
提问by DrivingInsanee
What laravel says:
什么 laravel 说：
$books = App\Book::with('author.contacts')->get();
What I need is something like this
我需要的是这样的
$books = App\Book::with('author[contacts,publishers]')->get();
where we eager load multiple relationships within a relationship.
我们急切地加载关系中的多个关系。
Is this possible?
这可能吗？
回答by oseintow
You can do
你可以做
$books = App\Book::with('author.contacts','author.publishers')->get();
回答by Elisha Senoo
Laravel documentation on eager loadingrecommends listing the relationships in an array as follows:
Laravel 上关于预先加载的文档建议按如下方式列出数组中的关系：
$books = App\Book::with(['author.contacts', 'author.publishers'])->get();
You can have as many relationships as desired. You can also specify which columns should be included for a relationship like this:
您可以根据需要拥有任意数量的关系。您还可以指定应为关系包含哪些列，如下所示：
//only id, name and email will be returned for author
//id must always be included
$books = App\Book::with(['author: id, name, email', 'author.contacts', 'author.publishers'])->get();
You may also add constrains as follows:
您还可以按如下方式添加约束：
$books = App\Book::with(['author: id, name, email' => function ($query) {
$query->where('title', 'like', '%first%');
}, 'email', 'author.contacts', 'author.publishers'])->get();
