Introduce new listbox renderer ListBoxDeferredListRenderer

This rendered allow to store, asynchronously, query results in active process, page by page,
Then as final rendering, this rendered will merge all temp results into a single one list.
Finally regular Page Templates can work out of the box.

product/ERP5Form/ListBox.py

@@ -479,6 +479,9 @@ class ListBoxWidget(Widget.Widget):
         if render_format == 'list':
           renderer = ListBoxListRenderer(self, field, REQUEST,
                                          render_prefix=render_prefix)
+        elif render_format == 'deferred_list':
+          renderer = ListBoxDeferredListRenderer(self, field, REQUEST,
+                                                 render_prefix=render_prefix)
         else:
           renderer = ListBoxHTMLRenderer(self, field, REQUEST, render_prefix=render_prefix)
 
@@ -2734,6 +2737,46 @@ class ListBoxListRenderer(ListBoxRenderer):
 
     return listboxline_list
 
+class ListBoxDeferredListRenderer(ListBoxListRenderer):
+
+  def getSelectionName(self):
+    """Return the selection name.
+    """
+    return self.selection_name
+
+  def getLineStart(self):
+    """Return a requested start number.
+    """
+    return int(self.getParamDict().get('list_start', 0))
+
+  getLineStart = lazyMethod(getLineStart)
+
+  def getMaxLineNumber(self):
+    """Return the maximum number of lines shown in a page.
+    """
+    return self.field.get_value('lines')
+
+  def setSelectionName(self, selection_name):
+    self.selection_name = selection_name
+
+  def render(self, *args, **kw):
+    self.positinal_argument_list = args
+    self.named_argument_list = kw
+    if 'active_process_path' in kw:
+      portal = self.getContext().getPortalObject()
+      active_process_path = kw['active_process_path']
+      active_process = portal.restrictedTraverse(active_process_path)
+      listbox_list = []
+      for active_result in active_process.getResultList():
+        listbox_list.extend(active_result.getResult())
+      return listbox_list
+    return self
+
+  def call_render(self):
+    return super(ListBoxDeferredListRenderer, self).render()
+
+allow_class(ListBoxDeferredListRenderer)
+
 class ListBoxValidator(Validator.Validator):
     property_names = Validator.Validator.property_names
     message_names = Validator.Validator.message_names + ['required_not_found']
@@ -2937,7 +2980,8 @@ class ListBox(ZMIField):
   security.declareProtected('Access contents information', 'get_value')
   def get_value(self, id, **kw):
     if (id == 'default'):
-      if (kw.get('render_format') in ('list', )):
+      render_format = kw.get('render_format')
+      if render_format in ('list', 'deferred_list',):
         request = kw.get('REQUEST', None)
         if request is None:
           request = get_request()
@@ -2949,7 +2993,7 @@ class ListBox(ZMIField):
           self)
         return self.widget.render(field, self.generate_field_key(), None,
                                   request,
-                                  render_format=kw.get('render_format'),
+                                  render_format=render_format,
                                   render_prefix=kw.get('render_prefix'))
       else:
         return None