setting to chooze custom field for time limit

app/views/settings/_limit_by_estimation.erb

@@ -0,0 +1,22 @@
+<%
+  default = Setting.available_settings[SETTINGS_NAME.to_s]['default']
+%>
+<table>
+  <tbody>
+
+    <tr>
+      <th align="right"><%= t 'use_custom_field' %></th>
+      <td colspan="2">
+        <%=check_box_tag("settings[estimated_field_use]",1, settings['estimated_field_use']) %>
+      </td>
+    </tr>
+
+    <tr>
+      <th align="right"><%= t 'estimation_limit_custom_field' %></th>
+      <td colspan="2">
+        <%= select_tag("settings[estimated_field]",
+            options_from_collection_for_select(IssueCustomField.where(field_format: 'float').all, "id", "name", settings['estimated_field'])) %>
+      </td>
+    </tr>
+ </tbody>
+</table>

lib/issue_patch.rb

@@ -0,0 +1,31 @@
+require_dependency 'issue'
+
+module IssuePatch
+
+  def self.included(base) # :nodoc:
+    base.send(:include, InstanceMethods)
+    base.class_eval do
+      unloadable # Send unloadable so it will not be unloaded in development
+    end
+  end
+
+	module InstanceMethods
+		def estimated_internal
+			use = Setting[SETTINGS_NAME]['estimated_field_use'] 
+			if (use.nil? || use == false)
+				return estimated_hours
+			end
+
+			@custom_field_estimated_id ||= CustomField.find(Setting[SETTINGS_NAME]['estimated_field']).id
+			@estimated_internal ||= custom_field_values.select{|item| item.custom_field_id == @custom_field_estimated_id}.shift
+			@estimated_internal.nil? ? 0.to_f : @estimated_internal.value.to_f
+		end
+
+		def estimated_internal=(value)
+			@estimated_internal.value = value.to_f if !@estimated_internal.nil?
+		end
+  end
+end
+
+
+Issue.send(:include, IssuePatch)