php Laravel attach() 方法不适用于 hasMany 方
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Laravel attach() method not working to hasMany side
提问by Bledson
The application has the models:
该应用程序具有以下模型：
Atividade.php
抗疫网
class Atividade extends Eloquent {
public function intervencoes() {
return $this->belongsToMany('Intervencao');
}
}
Intervencao.php
干预.php
class Intervencao extends Eloquent {
public function atividades() {
return $this->hasMany('Atividade');
}
}
The following code works:
以下代码有效：
Atividade::find($id)->intervencoes()->attach($intervencao_id);
But, this...
但是这个...
Intervencao::find($id)->atividades()->attach($atividade_id);
Returns an BadMethodCallException:
返回一个 BadMethodCallException：
Call to undefined method Illuminate\Database\Query\Builder::attach()
调用未定义的方法 Illuminate\Database\Query\Builder::attach()
SOLUTION (thanks to @gnack):
解决方案（感谢@gnack）：
I was trying to set a many-to-many relationship, so just needed to change this...
我试图建立一个多对多的关系，所以只需要改变这个......
return $this->hasMany('Atividade');
To this:
对此：
return $this->belongsToMany('Atividade');
回答by Nick Coad
See the Laravel documentation here: http://laravel.com/docs/eloquent#inserting-related-models
请参阅此处的 Laravel 文档：http://laravel.com/docs/eloquent#inserting-related-models
Basically you have set up two different types of relationships for the same two tables - you've set up a many-to-many and a one-to-many. It looks as though you probably wanted a many-to-many, so you'll need to change this line:
基本上，您已经为相同的两个表设置了两种不同类型的关系 - 您已经设置了多对多和一对多。看起来您可能想要多对多，因此您需要更改此行：
return $this->hasMany('Atividade');
To this:
对此：
return $this->belongsToMany('Atividade');
This will set the relationship up as a many-to-many relationship, which will then support the attach()method.
这会将关系设置为多对多关系，然后支持该attach()方法。
The attach()method is only for many-to-many, for other relationships there's save()or saveMany()and associate()(see the docs linked above).
该attach()方法仅适用于多对多，其他关系有save()orsaveMany()和associate()（请参阅上面链接的文档）。
回答by warspite
attach()is for many-to-many relationships. It seems your relationship is supposed to be a many-to-many but you have not set it up correctly for that.
attach()用于多对多关系。看起来你们的关系应该是多对多的，但你没有为此正确设置。
class Intervencao extends Eloquent {
public function atividades() {
return $this->belongsToMany('Atividade');
}
}
Then the attach()should work
然后attach()应该工作
回答by UserHelpNeeding02356
See the documentation Laravel 5.7
请参阅文档 Laravel 5.7
A Comment belongTo an unique Post
评论属于一个独特的帖子
class Comment extends Model
{
/**
* Get the post that owns the comment.
*/
public function post()
{
return $this->belongsTo('App\Post');
}
}
A Post can Have multiple Comments
一个帖子可以有多个评论
class Post extends Model
{
/**
* Get the comments for the blog post.
*/
public function comments()
{
return $this->hasMany('App\Comment');
}
When you want to update/delete a belongsTo relationship, you may use the associate/dissociate method.
当你想更新/删除一个belongsTo关系时，你可以使用associate/dissociate方法。
$post= App\Post::find(10);
$comment= App\Comment::find(3);
$comment->post()->associate($post); //update the model
$comment->save(); //you have to call save() method
//delete operation
$comment->post()->dissociate();
$comment->save(); //save() method
