在 Laravel 中加载所有关系及其子项

Question

我有一个包含多个关系的相当复杂的结构。如果我的关系是这样定义的，我怎样才能在一次调用中加载所有关系？

Model
    (has many) ChildModels1
        Child1a
        Child1b
        ...
    (has many) ChildModels2
        Child2a
        Child2b
        ...
    (has many) ChildModels3
        Child3a
        Child3a
            Child3aa
            Child3ab
            ...

我可以做到以下几点：

$entity = Entity::find($id)->load('ChildModels1', 'ChildModels2', 'ChildModels3');

但我也不确定如何加载所有子关系。

Answer 1

这可以通过预加载来实现：

Entity::where('id', $id)->with('relation1.subrelation1', 'relation1.subrelation2', 'relation2.subrelation1', 'relation2.subrelation2')->get();

When accessing Eloquent relationships as properties, the relationship data is "lazy loaded". This means the relationship data is not actually loaded until you first access the property. However, Eloquent can "eager load" relationships at the time you query the parent model. Eager loading alleviates the N + 1 query problem.

您可以在 Laravel documentation on eager loading 中阅读更多相关信息。

在 Laravel 中加载所有关系及其子项

Load all relations and their children in Laravel

laravel

laravel-5.1