BootstrapFormBuilder #rails #bootstrap3 #has-error, based on http://stackoverflow.com/a/22183501

bootstrap_form_builder.rb

#
# Bootstrap 3 integration for rails form_for
#
class BootstrapFormBuilder < ActionView::Helpers::FormBuilder
  # Creates a .form-group which adds .has-error automatically
  # Usage:
  #   <%= f.form_group :attribute_name %>
  # Result:
  #   <div class="form-group has-error" />
  # http://stackoverflow.com/a/22183501
  def form_group(method, options = {})
    class_def = 'form-group'
    class_def << ' has-error' unless @object.errors[method].blank?
    class_def << " #{options[:class]}" if options[:class].present?
    options[:class] = class_def
    @template.content_tag(:div, options) { yield }
  end

  # Creates a .help-text for every error when there are errors
  # Usage:
  #   <%= f.help_text :attribute_name %>
  # Result:
  #   <span class="help-text">Email måste anges</span>
  #   <span class="help-text">Email är fel</span>
  def help_text(method, options = {})
    return unless @object.errors[method].any?
    @object.errors.full_messages_for(method).map { |error|
      @template.content_tag(:span, error, class: 'help-block')
    }.join.html_safe
  end

  # Creates a .alert when errors are available
  # Usage:
  #   <%= f.alert_danger :attribute_name %>
  # Result:
  #   <div class="alert alert-danger">2 fel förhindrade denna ...</div>
  def alert_danger(options = {})
    return unless @object.errors.any?
    model = I18n.t("activerecord.models.#{@object.class.to_s.underscore}")
    text = I18n.t("activerecord.errors.template.header",
                  model: model,
                  count: @object.errors.full_messages.count)
    @template.content_tag(:div, text, class: "alert alert-danger").html_safe
  end
end