Have you ever wondered how to filter data for admin users in a rails app? If so, I present a reasonble way of doing it, such that you can use your existing form helpers via form_for. At first, filtering data in rails seems simple. You can just create a custom form using the form_tag helper right? The problem with using the form_tag helper is that once you are using form_tag you are no longer using a form builder to create the fields in your form. This would not be an issue if you were using the default builder that ships with Rails.

In my opinion the default builder is pretty lacking from a useability standpoint. This is the primary reason gems like simple_form exist. They give you a better starting point and quicker API for creating forms. At my day job, we have lovingly created our own form builder that makes building forms from our models very quick and easy. The problem we were facing was that our admin interfaces did not share the look and feel of the rest of the forms on our site because there wasn’t a simple way to use form_for to filter lists of data.

Enter, the FormFilterObject. The FormFilterObject is an object in our application that mimics an active record instance just enough to get form_for to work. Now that you know the punchline, let me show you some code to illustrate the point.

First the form builder.

    
class BootstrapFormBuilder < ActionView::Helpers::FormBuilder

def field_settings(method, options = {}, tag_value = nil)
field_name = "#{@object_name}_#{method.to_s}"
default_label = tag_value.nil? ? "#{method.to_s.gsub(/\_/, " ")}" : "#{tag_value.to_s.gsub(/\_/, " ")}"
label = options[:label] ? options.delete(:label) : default_label
options[:class] ||= ""
options[:class] += options[:required] ? " required" : ""
[field_name, label, options]
end

def check_box(method, options={}, checked_value = "1", unchecked_value = "0")
field_name, label, options = field_settings(method, options)
options[:help_placement] = "top" unless options[:help_placement]
options[:help_trigger] = "hover" unless options[:help_trigger]
str = ""
str << %Q{<div class="checkbox #{options[:class]}">}
str << %Q{<label for="#{field_name}">#{super} #{label}}
str << %Q{&nbsp;<a data-toggle="modal" data-target="##{field_name}_modal"><i class="glyph-help"></i></a>} if options[:help_modal]
str << %Q{&nbsp;<a data-toggle="popover" data-target="##{field_name}_popover" data-placement="#{options[:help_placement]}" data-title="#{options[:help_header]}" data-trigger="#{options[:help_trigger]}"><i class="glyph-help"></i></a>} if options[:help_popover]
str << %Q{</label>}
str << %Q{</div>}
if options[:help_modal]
str << %Q{<div class="modal fade" id="#{field_name}_modal"><div class="modal-dialog"><div class="modal-content"><div class="modal-header"><button type="button" class="close" data-dismiss="modal">&times;</button>}
str << %Q{<h3>#{options[:help_header]}</h3>} if options[:help_header]
str << %Q{</div><div class="modal-body">#{options[:help_modal]}</div><div class="modal-footer"><a href="#" class="btn btn-default" data-dismiss="modal">Close</a></div></div></div></div>}
end
str << %Q{<span class="hide" id="#{field_name}_popover">#{options[:help_popover]}</span>} if options[:help_popover]
str.html_safe
end

def radio_button(method, tag_value, options = {})
field_name, label, options = field_settings(method, options)
options[:help_placement] = "top" unless options[:help_placement]
options[:help_trigger] = "hover" unless options[:help_trigger]
str = ""
str << %Q{<div class="radio #{options[:class]}">}
str << %Q{<label for="#{field_name}">#{super} #{label}}
str << %Q{&nbsp;<a data-toggle="modal" href="##{field_name}_modal"><i class="glyph-help"></i></a>} if options[:help_modal]
str << %Q{&nbsp;<a data-toggle="popover" data-target="##{field_name}_popover" data-placement="#{options[:help_placement]}" data-title="#{options[:help_header]}" data-trigger="#{options[:help_trigger]}"><i class="glyph-help"></i></a>} if options[:help_popover]
str << %Q{</label>}
str << %Q{</div>}
if options[:help_modal]
str << %Q{<div class="modal fade" id="#{field_name}"><div class="modal-dialog"><div class="modal-content"><div class="modal-header"><button type="button" class="close" data-dismiss="modal">&times;</button>}
str << %Q{<h3>#{options[:help_header]}</h3>} if options[:help_header]
str << %Q{</div><div class="modal-body">#{options[:help_modal]}</div><div class="modal-footer"><a href="#" class="btn btn-default" data-dismiss="modal">Close</a></div></div></div></div>}
end
str << %Q{<span class="hide" id="#{field_name}_popover">#{options[:help_popover]}</span>} if options[:help_popover]
str.html_safe
end

def select(method, choices, options = {}, html_options = {})
field_name, label, options = field_settings(method, options)
options[:help_placement] = "top" unless options[:help_placement]
options[:help_trigger] = "hover" unless options[:help_trigger]
options[:feedback] = "has-feedback has-required" if options[:required] && options[:feedback] !~ /required/
options[:feedback] = options[:feedback].to_s + " has-help" if options[:help_popover] && (!options[:feedback] || options[:feedback] !~ /help/)
(html_options[:class] ||= "") << " input-lg form-control"
str = ""
str << %Q{<div class="form-group #{options[:icon]} #{options[:feedback]}">}
str << %Q{<label for="#{field_name}"#{(options[:sr_only] ? ' class="sr-only"' : "")}>#{label}}
str << %Q{&nbsp;<a data-toggle="modal" href="##{field_name}_modal"><i class="glyph-help"></i></a>} if options[:help_modal]
str << %Q{&nbsp;<a data-toggle="popover" data-target="##{field_name}_popover" data-placement="#{options[:help_placement]}" data-title="#{options[:help_header]}" data-trigger="#{options[:help_trigger]}"><i class="glyph-help"></i></a>} if options[:help_popover]
str << %Q{</label>}
str << %Q{<span id="helpBlock" class="help-block">#{options[:help_block]}</span>} if options[:help_block]
str << %Q{#{super}}
str << %Q{</div>}
if options[:help_modal]
str << %Q{<div class="modal fade" id="#{field_name}"><div class="modal-dialog"><div class="modal-content"><div class="modal-header"><button type="button" class="close" data-dismiss="modal">&times;</button>}
str << %Q{<h3>#{options[:help_header]}</h3>} if options[:help_header]
str << %Q{</div><div class="modal-body">#{options[:help_modal]}</div><div class="modal-footer"><a href="#" class="btn btn-default" data-dismiss="modal">Close</a></div></div></div></div>}
end
str << %Q{<span class="hide" id="#{field_name}_popover">#{options[:help_popover]}</span>} if options[:help_popover]
str.html_safe
end

def file_field(method, options = {})
options[:type] = "file"
text_field(method, options)
end

def password_field(method, options = {})
options[:type] = "password"
text_field(method, options)
end

def text_field(method, options = {})
field_name, label, options = field_settings(method, options)
options[:help_placement] = "top" unless options[:help_placement]
options[:help_trigger] = "hover" unless options[:help_trigger]
(options[:class] ||= "") << " input-xlg form-control"
options[:placeholder] = "#{label}" if options[:glyph]
options[:feedback] = "has-feedback has-required" if options[:required] && options[:feedback] !~ /required/
options[:feedback] = options[:feedback].to_s + " has-help" if options[:help_popover] && (!options[:feedback] || options[:feedback] !~ /help/)
str = ""
str << %Q{<div class="form-group #{options[:icon]} #{options[:feedback]}#{(options[:help_block] ? ' has-help' : "")}">}
if [label, options[:glyph]].any?(&:present?)
str << %Q{<label for="#{field_name}"#{(options[:glyph]||options[:sr_only] ? ' class="sr-only"' : "")}>#{label}}
str << %Q{&nbsp;<a data-toggle="modal" href="##{field_name}_modal"><i class="glyph-help"></i></a>} if options[:help_modal]
str << %Q{&nbsp;<a data-toggle="popover" data-target="##{field_name}_popover" data-placement="#{options[:help_placement]}" data-title="#{options[:help_header]}" data-trigger="#{options[:help_trigger]}"><i class="glyph-help"></i></a>} if options[:help_popover]
str << %Q{</label>}
end
str << %Q{<span id="helpBlock" class="help-block">#{options[:help_block]}</span>} if options[:help_block]
if options[:glyph]
str << %Q{<div class="input-group">}
str << %Q{<div class="input-group-addon glyph-#{options[:glyph]} size32"></div>}
end
str << %Q{#{super}}
str << %Q{</div>} if options[:glyph]
if options[:required]
str << %Q{<span class="size32 form-control-feedback" aria-hidden="true">*</span>}
else
str << %Q{<span class="#{options[:feedback_glyph]} size32 form-control-feedback" aria-hidden="true"></span>}
end
str << %Q{</div>}
if options[:help_modal]
str << %Q{<div class="modal fade" id="#{field_name}"><div class="modal-dialog"><div class="modal-content"><div class="modal-header"><button type="button" class="close" data-dismiss="modal">&times;</button>}
str << %Q{<h3>#{options[:help_header]}</h3>} if options[:help_header]
str << %Q{</div><div class="modal-body">#{options[:help_modal]}</div><div class="modal-footer"><a href="#" class="btn btn-default" data-dismiss="modal">Close</a></div></div></div></div>}
end
str << %Q{<span class="hide" id="#{field_name}_popover">#{options[:help_popover]}</span>} if options[:help_popover]
str.html_safe
end

def text_area(method, options = {})
field_name, label, options = field_settings(method, options)
options[:help_placement] = "top" unless options[:help_placement]
options[:help_trigger] = "hover" unless options[:help_trigger]
options[:feedback] = "has-feedback has-required" if options[:required] && options[:feedback] !~ /required/
options[:feedback] = options[:feedback].to_s + " has-help" if options[:help_popover] && (!options[:feedback] || options[:feedback] !~ /help/)
classes = options.fetch(:class,"").gsub(/\s+/m, ' ').strip.split(" ")
classes << "form-control"
classes << "input-xlg" if (classes & ["input-sm","input-lg","input-xlg","input-xxlg"]).size.zero?
options[:class] = classes.join(" ").strip

str = ""
str << %Q{<div class="form-group #{options[:icon]} #{options[:feedback]}">}

if [label].any?(&:present?)
str << %Q{<label for="#{field_name}"#{(options[:sr_only] ? ' class="sr-only"' : "")}>#{label}}
str << %Q{&nbsp;<a data-toggle="modal" href="##{field_name}_modal"><i class="glyph-help"></i></a>} if options[:help_modal]
str << %Q{&nbsp;<a data-toggle="popover" data-target="##{field_name}_popover" data-placement="#{options[:help_placement]}" data-title="#{options[:help_header]}" data-trigger="#{options[:help_trigger]}"><i class="glyph-help"></i></a>} if options[:help_popover]
str << %Q{</label>}
end

str << %Q{<span id="helpBlock" class="help-block">#{options[:help_block]}</span>} if options[:help_block]
str << %Q{#{super}}
if options[:required]
str << %Q{<span class="size32 form-control-feedback" aria-hidden="true">*</span>}
else
str << %Q{<span class="#{options[:feedback_glyph]} size32 form-control-feedback" aria-hidden="true"></span>}
end
str << %Q{</div>} unless options[:noformgroup]
if options[:help_modal]
str << %Q{<div class="modal fade" id="#{field_name}"><div class="modal-dialog"><div class="modal-content"><div class="modal-header"><button type="button" class="close" data-dismiss="modal">&times;</button>}
str << %Q{<h3>#{options[:help_header]}</h3>} if options[:help_header]
str << %Q{</div><div class="modal-body">#{options[:help_modal]}</div><div class="modal-footer"><a href="#" class="btn btn-default" data-dismiss="modal">Close</a></div></div></div></div>}
end
str << %Q{<span class="hide" id="#{field_name}_popover">#{options[:help_popover]}</span>} if options[:help_popover]
str.html_safe
end


end

Once you have a useful form builder that does what you want for form_for you can then use it by passing it into your form_for helper as follows.

<% # where @setting is an instance of and ActiveRecord based model %>
<%= form_for(@setting, :builder => BootstrapFormBuilder do |f| %>
<%= f.text_field :nickname %>
<%= f.check_box :never_send_me_an_email_for_any_reason, :label=>"Never send me an email for any reason" %>
<%= f.submit %>
<% end %>

While this is great for a single model it does not help you sort through and filter multiple models in a useful way. This is where FormFilterObject comes in handy. Here is an example of what a FormFilterObject might look like.

  # goes in controller or in some sort of helper....
class AdminSettingController < ApplicationController
def index
klass = Class.new do
include ActiveModel::Model
def self.name
"SettingFilterObject"
end
def method_missing(m, *args, &block)
self.open_struct ||= OpenStruct.new
self.open_struct.send(m, *args)
end
end
@instance = klass.new(params[:setting_filter_object] || {items_per_page: 10})
@settings = Setting.all
[:nickname, :never_send_me_an_email_for_any_reason].each do |filter|
if @instance.send(filter).present?
@settings = @settings.where(filter: @instance.send(filter))
end
end
@settings = @settings.paginate(page: params[:page], per_page: @instance.items_per_page)
end
end

your view code would look something like this

  <%= form_for(@instance, as: :setting_filter_object, url: "", builder: BootstrapFormBuilder, method: :get do |f| %>
<%= f.text_field :nickname %>
<%= f.check_box :never_send_me_an_email_for_any_reason, :label=>"Never send me an email for any reason" %>
<%= f.text_field :items_per_page %>
<%= f.submit %>
<% end %>

<ul>
<% @settings.each do |setting| %>
<li><%= setting.id %></li>
<% end %>
</ul>

That should be enough to get you started with more forms that filter ActiveRecord Object. I realize this post is fairly specific and many won’t find it generally useful, but if you do please leave me a quick comment.