Keep composite field values after a validation error

Previously the submitted value for a composite field was lost if the
form had a validation error.

Fixes danni#18

Author: Tim Heap

postgres_composite_types/forms.py

@@ -109,6 +109,16 @@ def __init__(self, *args, fields=None, model=None, **kwargs):
                                  self.widget.widgets.values()):
             widget.attrs['placeholder'] = field.label
 
+    def prepare_value(self, value):
+        """
+        Prepare the field data for the CompositeTypeWidget, which expects data
+        as a dict.
+        """
+        if isinstance(value, CompositeType):
+            return value.__to_dict__()
+
+        return value
+
     def validate(self, value):
         pass
 
@@ -155,7 +165,9 @@ def get_bound_field(self, form, field_name):
 
 class CompositeTypeWidget(forms.Widget):
     """
-    Takes an ordered dict of widgets to produce a composite form widget
+    Takes an ordered dict of widgets to produce a composite form widget. This
+    widget knows nothing about CompositeTypes, and works only with dicts for
+    initial and output data.
     """
     template_name = \
         'postgres_composite_types/forms/widgets/composite_type.html'
@@ -170,7 +182,7 @@ def __init__(self, widgets, **kwargs):
 
     @property
     def is_hidden(self):
-        return all(w.is_hidden for w in self.widgets)
+        return all(w.is_hidden for w in self.widgets.values())
 
     def get_context(self, name, value, attrs):
         context = super().get_context(name, value, attrs)
@@ -187,12 +199,9 @@ def get_context(self, name, value, attrs):
             if id_:
                 widget_attrs['id'] = '%s-%s' % (id_, subname)
 
-            subwidgets[subname] = widget.render('%s-%s' % (name, subname),
-                                                getattr(value, subname, None),
-                                                final_attrs)
             widget_context = widget.get_context(
                 '%s-%s' % (name, subname),
-                getattr(value, subname, None),
+                value.get(subname),
                 widget_attrs)
             subwidgets[subname] = widget_context['widget']
 

tests/test_forms.py

@@ -55,6 +55,13 @@ def test_validation(self):
         # Errors should be formatted like 'Label: Error message'
         self.assertEqual(str(form.errors['simple_field'][0]),
                          'A number: Enter a whole number.')
+        # Fields with validation errors should render with their invalid input
+        self.assertHTMLEqual(
+            str(form['simple_field']['a']),
+            """
+            <input id="id_simple_field-a" name="simple_field-a"
+                placeholder="A number" required type="number" value="one" />
+            """)
 
     def test_subfield_validation(self):
         """Errors on subfields should be accessible"""