Criando um FormFilter no rails

01_sponsor.rb

# Este aquivo fica em app/models/sponsor.rb

class Sponsor < ActiveRecord::Base
  # aqui fica meu codigo e scopes
end

02_members_controller.rb

# Este cocdigo fica em app/controllers/members_controller.rb

class MembersController < ApplicationController
  before_action :default_filters

  # Estou usando a gem has_scope
  has_scope :page, :default => 1

  # GET /members
  def index
    authorize :sponsor # usando a gem pundit

    respond_with collection
  end

  # aqui estão minhas actions, o que não vem ao caso mostrar agora
  
  private

  # Definindo os valores padrão para meus filtros
  def default_filters
    params[:filter] ||= {}
    params[:filter][:document_status] = params[:filter].fetch(
      :document_status,
      (current_user.employee? ? DocumentStatusFilterValues::UNVERIFIED : DocumentStatusFilterValues::BOTH)
    )
    params[:filter][:card_photo] = params[:filter].fetch(
      :card_photo,
      BooleanFilterValues::BOTH
    )
    params[:filter][:proof_residence_photo] = params[:filter].fetch(
      :proof_residence_photo,
      BooleanFilterValues::BOTH
    )
    params[:filter][:identification_photo] = params[:filter].fetch(
      :identification_photo,
      BooleanFilterValues::BOTH
    )
  end

  # Only allow a trusted parameter "white list" through.
  def filter_params
    return {} if params[:filter].blank?

    params
      .require( :filter )
      .permit( policy(:member).permitted_filter_attributes )
  end

  def resource_class
    @resource_class ||= Sponsor
  end
  helper_method :resource_class

  def resource_name
    @resource_name ||= :sponsor
  end
  helper_method :resource_name

  def resource
    @member ||= Sponsor.find(params[:id])
  end
  helper_method :resource

  def filter
    @filter ||= MemberFilter.new filter_params
  end
  helper_method :filter

  def collection
    @members ||= apply_scopes( filter.collection )
  end
  helper_method :collection
end

03_index.html.erb

<%# Este aquivo se encontra em app/views/members/index.html.erb%>

<div class="panel panel-default">
  <div class="panel-heading">
    <h4><%= t "title.member.index" %></h4>
  </div>

  <div class="panel-body">
    <div class="row">
      <div class="col-xs-12 col-sm-12 col-md-12 col-lg-12">
        <%= simple_form_for filter, :url => members_path, :method => :get, :as => :filter do |f| %>
          <div class="input-group" >
            <%= f.text_field :search, :placeholder => t('placeholder.member.search'), :class => "form-control" %>
            <span class="input-group-btn">
              <button class="btn btn-success" title="Buscar" type="submit">
                <i class="fa fa-search"></i>
              </button>
            </span>
          </div>

          <div class="row">
            <div class="col-xs-12 col-sm-12 col-md-12 col-lg-12">
              <h5><%= t "title.member.filter" %></h5>
            </div>

            <div class="col-xs-3 col-sm-3 col-md-3 col-lg-3">
              <%= f.input :document_status, :collection => DocumentStatusFilterValues.to_a %>
            </div>

            <div class="col-xs-3 col-sm-3 col-md-3 col-lg-3">
              <%= f.input :identification_photo, :collection => BooleanFilterValues.to_a %>
            </div>

            <div class="col-xs-3 col-sm-3 col-md-3 col-lg-3">
              <%= f.input :proof_residence_photo, :collection => BooleanFilterValues.to_a %>
            </div>

            <div class="col-xs-3 col-sm-3 col-md-3 col-lg-3">
              <%= f.input :card_photo, :collection => BooleanFilterValues.to_a %>
            </div>
          </div>

          <div class="text-right">
            <button class="btn btn-success" title="Buscar" type="submit">
              <i class="fa fa-search"></i>
              Filter
            </button>
          </div>
        <% end %>
      </div>
    </div>

    <hr/>

    <div class="row">
      <%- collection.each do |resource| %>
        <div class="col-xs-12 col-sm-6 col-md-6 col-lg-6">
          <div class="panel panel-info">
            <div class="panel-heading">
              <h4><%= decore(resource).to_s %></h4>
            </div>
            <div class="panel-body">
              <div class="row text-muted">
                <div class="col-xs-12 col-sm-12 col-md-6 col-lg-6">
                  <strong class="font-16">
                    <%= decore(resource.user).human_attribute_name :nickname %>
                  </strong>
                  <br />
                  <%= decore(resource).nickname %>
                </div>


                <div class="col-xs-12 col-sm-12 col-md-6 col-lg-6">
                  <strong class="font-16">
                    <%= resource_class.human_attribute_name :email %>
                  </strong>
                  <br />
                  <%= decore(resource).email %>
                </div>
              </div>

              <hr/>

              <div class="row text-muted">
                <div class="col-xs-6 col-sm-6 col-md-6 col-lg-6">
                  <strong>
                    <%= resource_class.human_attribute_name :created_at %>
                  </strong>
                  <br />
                  <%= decore(resource).created_at %>
                </div>

                <div class="col-xs-6 col-sm-6 col-md-6 col-lg-6">
                  <strong>
                    <%= resource_class.human_attribute_name :updated_at %>
                  </strong>
                  <br />
                  <%= decore(resource).updated_at %>
                </div>
              </div>
            </div>

            <div class="panel-footer text-right" style="padding-bottom: 10px; padding-right: 10px;">
              <%= link_to(member_path(resource), :class => "btn btn-sm btn-primary") do %>
                <i class="fa fa-eye"></i>
                <span><%= t "button.member.show" %></span>
              <% end if policy(resource, :member).show? %>

              <%= link_to(edit_member_path(resource), :class => "btn btn-sm btn-primary") do %>
                <i class="fa fa-edit"></i>
                <span><%= t "button.member.edit" %></span>
              <% end if policy(resource, :member).edit? %>

              <%= link_to(resource, :method => :delete, :data => { :confirm => t("messages.button.confirm.destroy") }, :class => "btn btn-sm btn-danger") do %>
                <i class="fa fa-trash-o"></i>
                <span><%= t "button.member.destroy" %></span>
              <% end if policy(resource, :member).destroy? %>
            </div>
          </div>
        </div>
      <% end %>
    </div>
  </div>

  <div class="panel-footer">
    <%= paginate collection %>
  </div>
</div>

11_base.rb

# Este arquivo fica em lib/form_object.rb

module FormObject
  class Base
    extend EnumerateIt
    include ActiveModel::Model

    attr_accessor :created_at, :updated_at

    class << self
      def i18n_scope
        :form_object
      end

      def decimal_attribute(*methods)
        separator = I18n.t(:'number.format.separator')
        delimiter = I18n.t(:'number.format.delimiter')

        methods.each do |method|
          define_method(:"#{method}=") do |value|
            if value.to_s =~ %r(\A\d{1,3}(#{"\\#{delimiter}"}?\d{3})*#{"\\#{separator}"}\d+\z)
                value = BigDecimal.new value.to_s.gsub(delimiter, '').gsub(separator, '.')
            end

            instance_variable_set "@#{method}", value
          end

          define_method(:"#{method}") do
            instance_variable_get "@#{method}"
          end
        end
      end
    end

    def attributes=(params)
      params.each do |attr, value|
        self.public_send("#{attr}=", value)
      end if params
    end

    def created_at
      @created_at ||= Time.current
    end

    def updated_at
      @updated_at ||= Time.current
    end
  end
end

12_member_filter_form.rb

# Este aquivo está em app/form_objects/member_filter_form.rb
# Mesmo eu usando ele como um form_object, ele é também um query_object


class MemberFilter < FormObject::Base
  attr_accessor :search, :card_photo, :proof_residence_photo
  attr_accessor :identification_photo, :document_status

  with_options :with => BooleanFilterValues do |o|
    o.has_enumeration_for :card_photo, :create_helpers => { :prefix => true }
    o.has_enumeration_for :identification_photo, :create_helpers => { :prefix => true }
    o.has_enumeration_for :proof_residence_photo, :create_helpers => { :prefix => true }
  end
  has_enumeration_for :document_status, :with => DocumentStatusFilterValues,
    :create_helpers => { :prefix => true }

  def collection(force_reload = false)
    @collection = nil if force_reload
    @collection ||= begin
                      relation = Sponsor.ordered.search(self.search)

                      relation = self.document_status_scope(relation)
                      relation = self.card_photo_scope(relation)
                      relation = self.proof_residence_photo_scope(relation)
                      relation = self.identification_photo_scope(relation)

                      relation
                    end
  end

  def document_status_scope(relation)
    case self.document_status
    when DocumentStatusFilterValues::VERIFIED then
      relation.verified
    when DocumentStatusFilterValues::UNVERIFIED then
      relation.unverified
    when DocumentStatusFilterValues::REJECTED then
      relation.rejected
    else # DocumentStatusFilterValues::BOTH
      relation
    end
  end

  def card_photo_scope(relation)
    case self.card_photo
    when BooleanFilterValues::YES then
      relation.with_card_photo
    when BooleanFilterValues::NO then
      relation.without_card_photo
    else # BooleanFilterValues::BOTH
      relation
    end
  end

  def proof_residence_photo_scope(relation)
    case self.proof_residence_photo
    when BooleanFilterValues::YES then
      relation.with_proof_residence_photo
    when BooleanFilterValues::NO then
      relation.without_proof_residence_photo
    else # BooleanFilterValues::BOTH
      relation
    end
  end

  def identification_photo_scope(relation)
    case self.identification_photo
    when BooleanFilterValues::YES then
      relation.with_identification_photo
    when BooleanFilterValues::NO then
      relation.without_identification_photo
    else # BooleanFilterValues::BOTH
      relation
    end
  end
end

21_document_status_filter_values.rb

#Este aquivoe está em app/enumerations/document_status_filter_values.rb

class DocumentStatusFilterValues < EnumerateIt::Base
  associate_values :verified,
                   :unverified,
                   :rejected,
                   :both
end

22_boolean_filter_values.rb

#Este aquivoe está em app/enumerations/boolean_filter_values.rb

class BooleanFilterValues < EnumerateIt::Base
  associate_values :yes,
                   :no,
                   :both
end