Laravel attach() 方法不适用于 hasMany 方面

问题描述

应用程序具有模型:

class Atividade extends Eloquent {
    public function intervencoes() {
        return $this->belongsToMany('Intervencao');
    }
}

class Intervencao extends Eloquent {
    public function atividades() {
        return $this->hasMany('Atividade');
    }
}

以下代码有效:

Atividade::find($id)->intervencoes()->attach($intervencao_id);

但是，这个……

Intervencao::find($id)->atividades()->attach($atividade_id);

返回一个 BadMethodCallException:

Returns an BadMethodCallException:

调用未定义的方法 IlluminateDatabaseQueryBuilder::attach()

Call to undefined method IlluminateDatabaseQueryBuilder::attach()

我试图设置多对多关系，所以只需要更改它...

I was trying to set a many-to-many relationship, so just needed to change this...

return $this->hasMany('Atividade');

为此:

return $this->belongsToMany('Atividade');

推荐答案

在此处查看 Laravel 文档:http://laravel.com/docs/eloquent#inserting-related-models

See the Laravel documentation here: http://laravel.com/docs/eloquent#inserting-related-models

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:

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:

return $this->hasMany('Atividade');

为此:

return $this->belongsToMany('Atividade');

这会将关系设置为多对多关系，然后将支持 attach() 方法.

This will set the relationship up as a many-to-many relationship, which will then support the attach() method.

attach() 方法仅适用于多对多，对于其他关系有 save() 或 saveMany() 和associate()(参见上面链接的文档).

The attach() method is only for many-to-many, for other relationships there's save() or saveMany() and associate() (see the docs linked above).

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