laravel eloquent 中的一对多关系
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One-To-Many Relationships in laravel eloquent
提问by Santiago Capdevila
Good morning, I am having a little trouble with model relationships in Eloquent, I need to link articles and images for those articles with an intermediate table. In the intermediate table I'd like to add the id's of both article and image, and I would like to retrieve all the images belonging to an article, what would be the best way to manage the relationship? Thanks in advance
早上好，我在 Eloquent 中的模型关系方面遇到了一些麻烦，我需要将这些文章的文章和图像与中间表链接起来。在中间表中，我想添加文章和图像的 id，并且我想检索属于文章的所有图像，管理关系的最佳方法是什么？提前致谢
采纳答案by Saumya Rastogi
You can use morphMany()relationship (Polymorphic Relationship) to solve your problem like this:
您可以使用morphMany()关系（多态关系）来解决您的问题，如下所示：
UPDATE: The table structure goes like this:
更新：表结构如下：
- articles
- id
- title
- content
- ...
- images
- id
- owner_id
- owner_type (Here there can be - Article, Auction, User, etc)
- name
- mime_type
- ...
Polymorphic relationsallow a model to belong to more than one other model on a single association. For example, imagine users of your application can "comment" both posts and videos. Using polymorphic relationships, you can use a single comments table for both of these scenarios.
多态关系允许一个模型在单个关联上属于多个其他模型。例如，假设您的应用程序的用户可以“评论”帖子和视频。使用多态关系，您可以对这两种情况使用单个注释表。
You models will look like this:
您的模型将如下所示：
class Article extends Model
{
public function images()
{
return $this->morphMany(Image::class, 'owner');
}
}
class Image extends Model
{
public function owner()
{
return $this->morphTo();
}
}
To save multiple images to an article, you can do like:
要将多个图像保存到文章中，您可以执行以下操作：
$article->images()->create([... inputs_arr ...]);
and to fetch them, you can do this like:
并获取它们，您可以这样做：
$articleImages = Article::find($id)->images;
Hope this helps!
希望这可以帮助！
回答by Alexey Mezenin
You don't need to use pivot table since it's one-to-manyrelationship.
您不需要使用数据透视表，因为它是一对多的关系。
Just use hasMany()relation:
只需使用hasMany()关系：
public function images()
{
return $this->hasMany('App\Image');
}
And then use eager loadingto load all images with article:
然后使用预先加载来加载所有带有文章的图像：
$article = Article::with('images')->where('id', $articleId)->first();
