如何在Laravel中将'hasManyThrough'与3个以上的表一起使用? [英] How to use 'hasManyThrough' with more than 3 tables in Laravel?

问题描述

当前当您有 country>之类的内容时，可以使用hasManyThrough .用户>帖子

as stated in the docs the current hasManyThrough can be used when u have something like country > users > posts

这会导致类似 Country :: whereName('xx')-> posts; 太好了，但是如果我还有更多类似的东西

which result in something like Country::whereName('xx')->posts; which is great but what if i have more than that like

国家>城市>用户>帖子甚至

国家>城市>城镇用户>帖子

然后您将如何实现类似的内容，以便您可以编写与上面相同的内容

how would you then implement something like that so you can write the same as above

Country :: whereName('xx')->帖子; 或 Town :: whereName('xx')-> posts;

推荐答案

遗憾的是，没有一个简单的解决方案，所以这就是我所发现的

sadly there is no one easy solution, so heres what i found

1-将另一张表的外部ID添加到发布表中，并坚持 hasMany &属于，例如

1- add the other table foreign id into the post table and stick to the hasMany & belongsTo, ex.

posts
    id - integer
    country_id - foreign
    // etc...
    title - string

2-在每个表上都使用 hasManyThrough ，除了 user 和& post ，因为除非您想深入了解，否则没有必要.

2- go with the hasManyThrough on each table except user & post as there is no need unless you want to go deeper, ex.

countries
    id - integer
    name - string

cities
    id - integer
    country_id - foreign
    name - string

towns
    id - integer
    city_id - foreign
    name - string

users
    id - integer
    town_id - foreign
    name - string

posts
    id - integer
    user_id - foreign
    title - string

-因此，让我们尝试第二个选项

- so lets try with the 2nd option

1-设置您的很多和属于关系

2-在模型上设置 hasManyThrough .

3-要实现上述 Country :: whereName('xx')-> posts 的示例，我们向 country 模型中添加了另一种方法

3- to achieve the above example of Country::whereName('xx')->posts we add another method to the country model

// because Country::find($id)->towns, return an array
// so to get all the posts we have to loop over that
// and return a new array with all the country posts
public function posts()
{
    $posts = [];

    foreach ($this->towns as $town) {
        $posts[] = $town->posts;
    }

    return $posts;
}

4-整个操作都通过 foreign_id 进行，因此我们通过 id 而不是 名称 ，例如 Country :: find($ id)-> posts()

4- as the whole thing is working through the foreign_id so we search by the id instead of the name like Country::find($id)->posts()

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