雄辩的ORM渴望在许多关系中加载不同的记录

本文介绍了雄辩的ORM渴望在许多关系中加载不同的记录的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

背景

我有一个列表模型，属于并拥有多个订阅者。当然，一个订阅者属于并有很多列表。

I have a List model which belongs to and has many Subscriber. And of course a Subscriber which belongs to and has many List.

问题

我想要从多个列表中加载所有订阅者。但是，我只对不同的用户感兴趣，因为用户可以拥有并且确实属于多个列表。

I want to eager-load all subscribers from multiple lists. BUT, I am only interested in distinct subscribers, since a subscriber can have and indeed belong to multiple lists.

我的尝试

我使用了 （）方法，但这并没有产生任何喜悦。我也可以循环查看结果集，手动分割重复。只是想知道有没有办法让Laravel为我做肮脏的工作？

I have used the distinct() method but this hasn't yielded any joy. And I can also loop through the result set to manually slice out duplicates. Just wondering if there is a way of letting Laravel do the dirty job for me?

代码

    $lists = Input::get('listsarray');

    $addresses = Addressbook::with(array('subscribers' => function($query)
                    {
                        $query->where('active', '=', 1);
                        // $query->distinct(); //This didn't work
                    }))->whereIn('id', $lists)->get();

通过加入检索唯一订阅者

我会尽力解释，使用列表而不是地址簿因为我真的不了解你的模型，可能会引起进一步的混淆。

Retrieving unique subscribers through join

I'll try my best to explain it using Lists instead of Adressbook, because I couldn't really understand your model and that may introduce further confusion.

如果我正确地理解了你的意见，那么你试图检索所有与 id IN listarray 的列表。在这种情况下，Eager Loading不是正确的方法。渴望加载用于为模型预加载关联的目的，以便稍后使用它们。在您的情况下，您不会检索列表及其订阅者，而是唯一的订阅者

If I understood your comments correctly, you are trying to retrieve all unique subscribers that have associations with lists of id IN listarray. In that case, Eager Loading is not the proper way of doing that. Eager loading serves the purpose of pre-loading associations for a model, in order to use them later on. In your case, you are not retrieving Lists and their Subscribers, but rather the unique Subscribers themselves.

$lists = Input::get('listsarray');

$subscribers = Subscriber::join('list_subscriber', 'list_subscriber.subscriber_id', '=', 'subscribers.id')
    ->whereIn('list_subscriber.list_id', $lists)
    ->groupBy('list_subscriber.subscriber_id')
    ->get(array('subscribers.*'));

如果您还希望检索与此类订阅者相关联的所有列表，您可以这样做：

If you also wish to retrieve all lists associated with such subscribers, you can do so:

// Simply include a with('lists') and Eloquent will eager load them
$subscribers = Subscriber::with('lists')
    ->join('list_subscriber', 'list_subscriber.subscriber_id', '=', 'subscribers.id')
    ->whereIn('list_subscriber.list_id', $lists)
    ->groupBy('list_subscriber.subscriber_id')
    ->get(array('subscribers.*'));

Eager Loading

简单地提高性能，你不需要使用不同的，Laravel已经做到了。口头表现如下：

Eager Loading

If it's a matter of simply improving performance, you don't need to use distinct, Laravel already does it. Eloquent behaves like this:

获取所有列表。

通过列表迭代构建一组唯一的 list_ids

使用获取全部 list_subscribers WHERE list_id IN（X，Y，Z）

通过所有 list_subscribers 迭代创建一个唯一的 subscriber_id

获取使用 WHERE id IN（X，Y，Z）

Fetchs all lists.
Iterates through lists building an array of unique list_ids
Fetchs all list_subscribers using WHERE list_id IN (X, Y, Z)
Iterates through all list_subscribers building an array of unique subscriber_id
Fetchs all subscribers using WHERE id IN (X, Y, Z)

这篇关于雄辩的ORM渴望在许多关系中加载不同的记录的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！

subscribers