validation custom message for rails 3
Try this
validates :title, presence: { message: "Story title is required" }
Actually, I did this in a better way. If you want to remove the field title from the message you should use this on your _form.htmk.erb view:
As you can see inside this view:
<ul> <% @article.errors.full_messages.each do |msg| %> <li><%= msg %></li> <% end %></ul>
Replace it by:
<ul> <% @article.errors.each_with_index do |msg, i| %> <li><%= msg[1] %></li> <% end %></ul>
A custom message for a boolean with conditionals might be:
validates :foo, inclusion: { in: [true, false], message: "cannot be blank" }, if: :bar?