how to override model validation messages in rails 3 - ruby-on-rails

Question

I have a model,group_question_answer.rb
class GroupQuestionAnswer < ActiveRecord::Base
belongs_to :group_question
validates_presence_of :answer
validates_presence_of :answer_question
end
for attribute answer and answer_question i get error message as Group question answers answer can't be blank
I need to show only answer cant be blank.i even tried adding :message=>"cant be blank",but still i dont get my required message.how can i remove model name and can just arrtibute error message ....

Answer 1

class GroupQuestionAnswer < ActiveRecord::Base
attr_accessible :answer
validate do |group_question_answer|
errors.add(:base, "answer can't be blank") if group_question_answer.answer.blank?
end
end
works perfectly
rails c
Loading development environment (Rails 3.2.9)
irb(main):001:0> q = GroupQuestionAnswer.create
(0.1ms) begin transaction
(0.1ms) rollback transaction
=> #<GroupQuestionAnswer id: nil, answer: nil, created_at: nil, updated_at: nil>
irb(main):002:0> q
=> #<GroupQuestionAnswer id: nil, answer: nil, created_at: nil, updated_at: nil>
irb(main):003:0> q.save
(0.1ms) begin transaction
(0.1ms) rollback transaction
=> false
irb(main):004:0> q.errors
=> #<ActiveModel::Errors:0x007fc2fb325fa8 #base=#<GroupQuestionAnswer id: nil, answer: nil, created_at: nil, updated_at: nil>, #messages={:base=>["answer can't be blank"]}>
irb(main):006:0> q.errors.messages
=> {:base=>["answer can't be blank"]}
=> {:base=>["answer can't be blank"]}
irb(main):007:0> q = GroupQuestionAnswer.create(answer: "123")
(0.1ms) begin transaction
SQL (9.0ms) INSERT INTO "group_question_answers" ("answer", "created_at", "updated_at") VALUES (?, ?, ?) [["answer", "123"], ["created_at", Fri, 28 Dec 2012 11:01:38 UTC +00:00], ["updated_at", Fri, 28 Dec 2012 11:01:38 UTC +00:00]]
(1.1ms) commit transaction
=> #<GroupQuestionAnswer id: 1, answer: "123", created_at: "2012-12-28 11:01:38", updated_at: "2012-12-28 11:01:38">
irb(main):008:0> q.errors.messages
=> {}
In my opinion validate method perfect way to fully customize rails validations and that does exactly what you ask for.

Answer 2

You can try like this:
validates :answer, presence: { message: '<Your message>'}
validates :answer_question, presence: { message: '<Your message>'}

Answer 3

Try adding them in your config/locales/en.yml file
As there you can do something like this,
en:
errors:
messages:
answer: answer can't be blank