Add NamedMultiWidget class

Works as Django's MultiWidget but instead of a list
of subwidgets, uses a dictionary of subwidgets with names
as the keys. The named nature is less error prone than Django's
index numbered subwidgets.

Signed-off-by: Roberto Rosario <Roberto.Rosario@mayan-edms.com>

mayan/apps/common/widgets.py

@@ -1,5 +1,7 @@
 from __future__ import unicode_literals
 
+from collections import OrderedDict
+
 from django import forms
 from django.utils.safestring import mark_safe
 
@@ -20,6 +22,86 @@ class DisableableSelectWidget(forms.widgets.SelectMultiple):
         return result
 
 
+class NamedMultiWidget(forms.widgets.Widget):
+    template_name = 'django/forms/widgets/multiwidget.html'
+
+    def __init__(self, widgets, attrs=None):
+        self.widgets = OrderedDict()
+        for name, widget in widgets.items():
+            self.widgets[name] = widget() if isinstance(widget, type) else widget
+
+        super(NamedMultiWidget, self).__init__(attrs)
+
+    def _get_media(self):
+        "Media for a multiwidget is the combination of all media of the subwidgets"
+        media = forms.widgets.Media()
+        for name, widget in self.widgets.items():
+            media = media + widget.media
+        return media
+    media = property(_get_media)
+
+    @property
+    def is_hidden(self):
+        return all(widget.is_hidden for name, widget in self.widgets.items())
+
+    def get_context(self, name, value, attrs):
+        context = super(NamedMultiWidget, self).get_context(name, value, attrs)
+        if self.is_localized:
+            for widget in self.widgets:
+                widget.is_localized = self.is_localized
+
+        value = self.decompress(value)
+
+        final_attrs = context['widget']['attrs']
+        input_type = final_attrs.pop('type', None)
+        id_ = final_attrs.get('id')
+        subwidgets = []
+        for widget_name, widget in self.widgets.items():
+            if input_type is not None:
+                widget.input_type = input_type
+            full_widget_name = '%s_%s' % (name, widget_name)
+            try:
+                widget_value = value[widget_name]
+            except IndexError:
+                widget_value = None
+            if id_:
+                widget_attrs = final_attrs.copy()
+                widget_attrs['id'] = '%s_%s' % (id_, widget_name)
+            else:
+                widget_attrs = final_attrs
+            subwidgets.append(
+                widget.get_context(
+                    full_widget_name, widget_value, widget_attrs
+                )['widget']
+            )
+        context['widget']['subwidgets'] = subwidgets
+        return context
+
+    def id_for_label(self, id_):
+        if id_:
+            id_ += '_{}'.format(self.widgets.keys()[0])
+        return id_
+
+    def value_from_datadict(self, data, files, name):
+        return {
+            name: widget.value_from_datadict(
+                data, files, name + '_%s' % name
+            ) for name, widget in self.widgets.items()
+        }
+
+    def value_omitted_from_data(self, data, files, name):
+        return all(
+            widget.value_omitted_from_data(data, files, name + '_%s' % name)
+            for name, widget in self.widgets.items()
+        )
+
+    @property
+    def needs_multipart_form(self):
+        return any(
+            widget.needs_multipart_form for name, widget in self.widgets.items()
+        )
+
+
 class PlainWidget(forms.widgets.Widget):
     """
     Class to define a form widget that effectively nulls the htmls of a