In this example, I create a user
with no profile
, then later on create a profile
for that user. I tried using build with a has_one
association but that blew up. The only way I see this working is using has_many
. The user
is supposed to only have at most one profile
.
I have been trying this. I have:
class User < ActiveRecord::Base
has_one :profile
end
class Profile < ActiveRecord::Base
belongs_to :user
end
But when I do:
user.build_profile
I get the error:
ActiveRecord::StatementInvalid: Mysql::Error: Unknown column 'profiles.user_id' in 'where clause': SELECT * FROM `profiles` WHERE (`profiles`.user_id = 4) LIMIT 1
Is there a way in rails to have 0 or 1 association?
The build
method signature is different for has_one
and has_many
associations.
class User < ActiveRecord::Base
has_one :profile
has_many :messages
end
The build syntax for has_many
association:
user.messages.build
The build syntax for has_one
association:
user.build_profile # this will work
user.profile.build # this will throw error
Read the has_one
association documentation for more details.