加入获取组成员的查询，然后在Laravel中将组作为查询

I have a website build in Laravel. I have two tables - Groups and Group members.

For each group_member, the row in the table has id, group_id and user_id.

The groups have a name and a description.

When a user joins a group, a row is created in the group_member table.

But I now need to get the groups that a user is part of.

So if I have user_id = 5, I need to get all the rows in group_member where user_id = 5, and then get the corresponding group, so I can query the groups.

I need to do something like $groups = Groups::whereGroup_member ... But I cant query the model like that, because in Groups there is no where it specificies who the members are, it is just the group details - the members are specificed in group_member table.

How do I get the groups, which a member is part of using the laravel query standards?

In your User.php Model

public function group_member(){
     return $this->hasMany(GroupMember::class,'user_id','id;);
}

In your GroupMember.php Model

public function group(){
     return $this->belongsTo(Group::class,'group_id','id');
}

Your query will be

$users = User::with('group_member.group')->find($user_id);

You should use Many-to-Many relation:

class Group
...
public function members() {
    return $this->belongsToMany(User::class); // Users (members) that belongs to Group
}

class User
...
public function groups() {
    return $this->belongsToMany(Group::class, 'group_member', 'user_id', 'group_id'); // Groups that User belongs to
}

And at controller, when You have user id:

 $groups = User::where('id', $user_id)->groups;

More about this written at official docs: https://laravel.com/docs/5.4/eloquent-relationships#many-to-many