Question

I want user to remove group that user attending groups by removing groupings.
So, I tried write below the code , but when run leave action , it happen error that
Unknown key: group_id.But I don’t know how to deal with it . Please some help.
Thanks in advance.

GroupingsController.rb

def leave
  @user = current_user
  @group = Group.find(params[:id])
  @user.remove(@group)
  redirect_to :back , notice: "Destroy!"
end

User.rb

has_many :groups, :through => :groupings,:source => :group

def remove(group)
  groupings.find_by_group_id(:group_id => group).destroy
end

# attend method is work correctly.
def attend(group)
  groupings.create(:group_id => group)
end

Answer 1

You’ve already specified that you’re using group_id (by saying find_by_group_id) – so you don’t need to specify it again by passing it as a ‘key’ (eg :group_id =>)

So your code should just be

def remove(group)
  groupings.find_by_group_id(group.id).destroy
end