How do I display Ruby on Rails form validation error messages one at a time?

Question

I\'m trying to understand how I can achieve this. Can anyone advise me or point me in the right direction?

What I currently do, which is shown in the code snippet be

Answer 1

A better idea,

if you want to put the error message just beneath the text field, you can do like this

.row.spacer20top
  .col-sm-6.form-group
    = f.label :first_name, "*Your First Name:"
    = f.text_field :first_name, :required => true, class: "form-control"
    = f.error_message_for(:first_name)

---

What is error_message_for?
--> Well, this is a beautiful hack to do some cool stuff

# Author Shiva Bhusal
# Aug 2016
# in config/initializers/modify_rails_form_builder.rb
# This will add a new method in the `f` object available in Rails forms
class ActionView::Helpers::FormBuilder
  def error_message_for(field_name)
    if self.object.errors[field_name].present?
      model_name              = self.object.class.name.downcase
      id_of_element           = "error_#{model_name}_#{field_name}"
      target_elem_id          = "#{model_name}_#{field_name}"
      class_name              = 'signup-error alert alert-danger'
      error_declaration_class = 'has-signup-error'

      "
"\
      "#{self.object.errors[field_name].join(', ')}"\
      "
"\
      ""\
      "".html_safe
    end
  rescue
    nil
  end
end

---

Result

Markup Generated after error

has already been taken

Corresponding SCSS

  .has-signup-error{
    .signup-error{
      background: transparent;
      color: $brand-danger;
      border: none;
    }

    input, select{
      background-color: $bg-danger;
      border-color: $brand-danger;
      color: $gray-base;
      font-weight: 500;
    }

    &.checkbox{
      label{
        &:before{
          background-color: $bg-danger;
          border-color: $brand-danger;
        }
      }
    }

Note: Bootstrap variables used here