Generalized datatable class

app/controllers/admin/users_controller.rb

@@ -7,9 +7,10 @@ module Admin
     end
 
     def index
+      users_datatable = Datatable.new(view_context, User.where(nil), %w(name email), %w(id state email name))
       respond_to do |format|
         format.html
-        format.json { render json: UsersDatatable.new(view_context) }
+        format.json { render json: users_datatable.to_json(data: users_datatable.paginated_records.map {|user| users_datatable_data(user)}) }
       end
     end
 

app/datatables/datatable.rb

@@ -0,0 +1,48 @@
+class Datatable
+  delegate :params, to: :@view
+
+  def initialize(view, collection, search_columns, sort_columns)
+    @view = view
+    @collection = collection
+    @search_columns = search_columns
+    @sort_columns = sort_columns
+  end
+
+  def as_json(options={})
+    {
+      sEcho: params[:sEcho].to_i,
+      iTotalRecords: @collection.count,
+      iTotalDisplayRecords: records.count,
+      aaData: options[:data]
+    }
+  end
+
+  def paginated_records
+    paginate(records)
+  end
+
+  private
+
+  def records
+    @records ||= fetch_records
+  end
+
+  def fetch_records
+    sort_direction = params[:sSortDir_0] == 'desc' ? 'desc' : 'asc'
+    sort_column = @sort_columns[params[:iSortCol_0].to_i]
+    records = @collection.order("#{sort_column} #{sort_direction}")
+    if params[:sSearch].present? && @search_columns.present?
+      search_query = ''
+      @search_columns.each { |column| search_query += "#{column} like :search or " }
+      search_query = search_query.chomp(' or ')
+      records = records.where(search_query, search: "%#{params[:sSearch]}%")
+    end
+    records
+  end
+
+  def paginate(records)
+    per_page = params[:iDisplayLength].to_i > 0 ? params[:iDisplayLength].to_i : 10
+    page = params[:iDisplayStart].to_i / per_page + 1
+    records.offset((page - 1) * per_page).limit(per_page)
+  end
+end

app/datatables/users_datatable.rb

@@ -1,53 +0,0 @@
-class UsersDatatable
-  delegate :params, :link_to, :current_ability, :show_roles, to: :@view
-
-  def initialize(view)
-    @view = view
-  end
-
-  def as_json(_options = {})
-    {
-      sEcho: params[:sEcho].to_i,
-      iTotalRecords: User.count,
-      iTotalDisplayRecords: users.count,
-      aaData: data
-    }
-  end
-
-  private
-
-  def data
-    paginate(users).map do |user|
-      [
-        user.id,
-        (user.confirmed? ? 'confirmed' : 'unconfirmed'),
-        user.email,
-        user.name,
-        user.registrations.where(attended: true).count,
-        (user.roles.empty? ? 'None' : "#{show_roles(user.get_roles.first(2))} #{'...' if user.get_roles.count > 2}"),
-        (link_to('View', Rails.application.routes.url_helpers.admin_user_path(user), class: 'btn btn-success') if current_ability.can?(:show, user)),
-        (link_to('Edit', Rails.application.routes.url_helpers.edit_admin_user_path(user), class: 'btn btn-primary') if current_ability.can?(:update, user))
-      ]
-    end
-  end
-
-  def users
-    @users ||= fetch_users
-  end
-
-  def fetch_users
-    sort_direction = params[:sSortDir_0] == 'desc' ? 'desc' : 'asc'
-    sort_column = %w(id state email name)[params[:iSortCol_0].to_i]
-    users = User.order("#{sort_column} #{sort_direction}")
-    if params[:sSearch].present?
-      users = users.where('name like :search or email like :search', search: "%#{params[:sSearch]}%")
-    end
-    users
-  end
-
-  def paginate(users)
-    per_page = params[:iDisplayLength].to_i > 0 ? params[:iDisplayLength].to_i : 10
-    page = params[:iDisplayStart].to_i / per_page + 1
-    users.offset((page - 1) * per_page).limit(per_page)
-  end
-end

app/helpers/application_helper.rb

@@ -491,4 +491,17 @@ module ApplicationHelper
       end
     end
   end
+
+  def users_datatable_data(user)
+    [
+      user.id,
+      (user.confirmed? ? 'confirmed' : 'unconfirmed'),
+      user.email,
+      user.name,
+      user.registrations.where(attended: true).count,
+      (user.roles.empty? ? 'None' : "#{show_roles(user.get_roles.first(2))} #{'...' if user.get_roles.count > 2}"),
+      (view_context.link_to('View', admin_user_path(user), class: 'btn btn-success') if current_ability.can?(:show, user)),
+      (view_context.link_to('Edit', edit_admin_user_path(user), class: 'btn btn-primary') if current_ability.can?(:update, user))
+    ]
+  end
 end