Bootstrap 3 rails form builder

_form.html.erb

<%= bs_form_for [:backend, @publisher] do |f| %>
  <%= f.lock %>
  <%= f.error_messages %>

  <%= f.labeled_text_field :name %>
  <%= f.labeled_text_field :support_link, placeholder: "http://help.ea.com", hint: "Possibly visible to customers if given." %>
  <%= f.labeled_text_field :support_email, placeholder: "support@ea.com", hint: "Only for internal use." %>
  <%= f.indicate_tenant(:global) unless @publisher.persisted? %>

  <%= f.actions do %>
    <%= f.submit "submit" %> or <%= link_to "cancel", :back %>
  <% end %>
<% end %>

_form.png

_form_errors.html.erb

<% target, field = *[*target] %>
<% if field %>
  <% if target.error?(field) %>
    <span class="help-block text-danger">
      <% errors = target.errors[field] %>
      <% if errors.count > 1 %>
        <ul>
          <% errors.each do |err| %>
            <li><%= err %></li>
          <% end %>
        </ul>
      <% else %>
        <%= errors.first %>
      <% end %>
    </span>
  <% end %>
<% else %>
  <% if target.errors[:base].any? %>
    <div class="alert alert-danger">
      <button type="button" class="close" data-dismiss="alert">&times;</button>
      <h4>Errors occured</h4>
      <div>
        <ul>
          <% target.errors.full_messages_for(:base).each do |message| %>
            <li><%= message %></li>
          <% end %>
        </ul>
      </div>
    </div>
  <% end %>
<% end %>

application_helper.rb

module ApplicationHelper
  def bs_form_for(object, options = {}, &block)
    options[:builder] = Bootstrap3FormBuilder
    options[:bs]   ||= {}
    options[:html] ||= {}
    options[:html][:class] ||= "form-horizontal"
    form_for(object, options, &block)
  end
end

bootstrap3_form_builder.rb

class Bootstrap3FormBuilder < ActionView::Helpers::FormBuilder
  delegate :content_tag, :tag, :capture, to: :@template

  def label_cols
    @options[:bs].try(:[], :label_cols) || 2
  end

  def controls_cols
    @options[:bs].try(:[], :controls_cols) || 10
  end

  # labeled tags
  %w[text_field text_area password_field select file_field].each do |method_name|
    define_method("labeled_#{method_name}") do |name, *args, &block|
      labeled_custom(name, *args) do |errors_or_hint|
        content = block.try(:call) || __send__(method_name, name, *args)
        content + errors_or_hint
      end
    end
  end

  def bs_resize lcols = 2, ccols = 10
    if block_given?
      lcols_was = @options[:bs].try(:[], :label_cols)
      ccols_was = @options[:bs].try(:[], :controls_cols)
    end
    @options[:bs] ||= {}
    @options[:bs][:label_cols] = lcols
    @options[:bs][:controls_cols] = ccols
    yield if block_given?
  ensure
    if block_given?
      @options[:bs][:label_cols] = lcols_was
      @options[:bs][:controls_cols] = ccols_was
    end
  end

  # default input classes
  %w[text_field text_area password_field file_field].each do |method_name|
    define_method("#{method_name}") do |name, *args, &block|
      opts = args.extract_options!
      opts[:class] ||= "form-control"

      if object.class.respond_to?(:columns)
        col = object.class.columns.detect{|c| [:string, :text].include?(c.type) && c.name == name.to_s }
        if col && col.limit
          opts[:data] ||= {}
          opts[:data][:maxlength] ||= col.limit
        end
      end

      super(name, *args, opts)
    end
  end

  def select name, choices, opts = {}
    opts[:html] ||= {}
    opts[:html][:class] ||= "form-control"
    html_opts = opts.delete(:html)
    super(name, choices, opts, html_opts)
  end

  def submit *args
    opts = args.extract_options!
    opts[:class] ||= "btn btn-primary"
    super(*args, opts)
  end

  def labeled_static name, text = "", opts = {}, &block
    labeled_custom(name, opts) {|hint| static((text.presence || "#{capture(&block) if block}".presence || "#{object.try(name)}").html_safe + hint) }
  end

  def labeled_date_select name, opts = {}
    labeled_datetime_select(name, opts.merge(time: false))
  end

  def labeled_time_select name, opts = {}
    labeled_datetime_select(name, opts.merge(date: false))
  end

  def labeled_datetime_select name, opts = {}
    opts = opts.reverse_merge(pos: "before", date: true, time: true, locale: I18n.locale)
    icon_class = opts[:date] ? "calendar" : "clock-o"
    sopts = (opts.delete(:opts) || {}).reverse_merge(
      pickDate: opts[:date],
      pickTime: opts[:time],
      language: opts[:locale],
      useSeconds: false,
      minuteStepping: 15,
      startDate: "2000-1-1",
    )

    labeled_custom(name, opts) do |errors_or_hint|
      content = content_tag :div, data: sopts, class: "input-group bs-#{"date" if opts[:date]}#{"time" if opts[:time]}-select" do
        tf  = text_field(name, value: object.send(name))
        ico = content_tag(:span, class: "input-group-addon") do
          content_tag(:span, "", class: "fa fa-#{icon_class}", data: { "icon-element" => "" })
        end
        clear = content_tag(:a, @template.icon(:times), href: "#", class: "datetime-clear times")

        opts[:pos] == "before" ? ico + clear + tf : tf + clear + ico
      end
      content + errors_or_hint
    end
  end

  # ===========
  # = generic =
  # ===========

  def errors_or_hint name, hint
    (object.try(:error?, name) ? field_errors(name) : hint)
  end

  def labeled_custom name, *args, &block
    opts = args.last.is_a?(Hash) ? args.last : {}
    group name, opts[:group] do
      hint  = self.hint(opts.delete(:hint)) if opts[:hint]
      lopts = opts[:label].is_a?(String) ? { text: opts[:label] } : (opts[:label] || {})
      field_label(name, lopts[:text], lopts) + controls(capture("#{errors_or_hint(name, hint)}".html_safe, &block))
    end
  end

  def hint hints = {}
    hints = case hints
      when String, Array then { muted: hints }
      else hints
    end
    "".html_safe.tap do |o|
      hints.each do |type, msgs|
        [*msgs].each do |msg|
          o << content_tag(:span, content_tag(:span, msg, class: "text-#{type}"), class: "help-block")
        end
      end
    end
  end

  def group name = nil, opts = {}, &block
    opts ||= {}
    has_error = name && object.try(:error?, name) ? "has-error" : ""
    content_tag :div, opts.merge(class: "form-group #{has_error}") do
      capture(&block)
    end
  end

  def field_label(name, text = nil, opts = {})
    opts = opts.is_a?(String) ? { text: opts } : opts
    opts[:text]  ||= text
    opts[:class] ||= "col-md-#{label_cols} control-label"
    if object.class.respond_to?(:validators_on)
      opts[:class] << " required" if object.class.validators_on(name).any? { |v| v.kind_of? ActiveModel::Validations::PresenceValidator }
    end

    label(name, opts[:text], opts)
  end

  def controls text = nil, &block
    content_tag :div, class: "col-md-#{controls_cols}" do
      text || capture(&block)
    end
  end

  def static text = nil, &block
    content_tag :p, class: "form-control-static" do
      text || capture(&block)
    end
  end

  def actions text = nil, &block
    content_tag(:hr) +
    content_tag(:div, class: "form-group") do
      content_tag :div, class: "col-md-offset-#{label_cols} col-md-#{controls_cols}" do
        text || capture(&block)
      end
    end
  end

  def indicate_tenant which = nil
    value = case which
      when :all then "All existing tenants"
      when :global then @template.icon(:globe, "Global").to_s
      else (which || Tenant.current).try(:full_desc)
    end
    labeled_static :tenant_id, value
  end

  def error_messages
    @template.render "shared/form_errors", target: object
  end

  def field_errors name
    @template.render "shared/form_errors", target: [object, name]
  end

  def lock
    hidden_field :original_updated_at
  end

  private

  def objectify_options(options)
    super.except(:label)
  end
end