创建对象时的Ruby on Rails NoMethodError

Question

I am trying to create a new object with group.group_member.build however this throws an error:

NoMethodError: undefined method `group_member' for #<Group:0x007fe50d5468f8>

group.rb

belongs_to :owner
has_many :group_members

group_member.rb

belongs_to :group

I used owner.build_group which successfully created the group, I'm under the impression that group.group_member.build should do the same for the group_member object.

I have also tried group.group_members.build which returns a slightly different error:

ActiveRecord::UnknownAttributeError: unknown attribute: group_id

All help is appreciated, I can't seem to figure out the issue here. Thanks.

Answer 1

You need to use the name of the association, which is plural group.group_members . Update your code to use:

group.group_members.build

Your group_members table will need to have a group_id column for this to work.