Factors _QuantityBoxForm out of _ProductsForm

registrasion/forms.py

@@ -3,51 +3,83 @@ import models as rego
 from django import forms
 
 
-def ProductsForm(products):
+# Products forms -- none of these have any fields: they are to be subclassed
+# and the fields added as needs be.
 
-    PREFIX = "product_"
+class _ProductsForm(forms.Form):
 
-    def field_name(product):
-        return PREFIX + ("%d" % product.id)
-
-    class _ProductsForm(forms.Form):
+    PRODUCT_PREFIX = "product_"
 
+    ''' Base class for product entry forms. '''
     def __init__(self, *a, **k):
         if "product_quantities" in k:
-                initial = _ProductsForm.initial_data(k["product_quantities"])
+            initial = self.initial_data(k["product_quantities"])
             k["initial"] = initial
             del k["product_quantities"]
         super(_ProductsForm, self).__init__(*a, **k)
 
     @classmethod
-        def initial_data(cls, product_quantities):
+    def field_name(cls, product):
+        return cls.PRODUCT_PREFIX + ("%d" % product.id)
+
+    @classmethod
+    def set_fields(cls, products):
+        ''' Sets the base_fields on this _ProductsForm to allow selecting
+        from the provided products. '''
+        pass
+
+    @classmethod
+    def initial_data(cls, product_quantites):
         ''' Prepares initial data for an instance of this form.
         product_quantities is a sequence of (product,quantity) tuples '''
-            initial = {}
-            for product, quantity in product_quantities:
-                initial[field_name(product)] = quantity
-
-            return initial
+        return {}
 
     def product_quantities(self):
         ''' Yields a sequence of (product, quantity) tuples from the
         cleaned form data. '''
-            for name, value in self.cleaned_data.items():
-                if name.startswith(PREFIX):
-                    product_id = int(name[len(PREFIX):])
-                    yield (product_id, value, name)
+        return iter([])
 
+
+class _QuantityBoxProductsForm(_ProductsForm):
+    ''' Products entry form that allows users to enter quantities
+    of desired products. '''
+
+    @classmethod
+    def set_fields(cls, products):
         for product in products:
-
             help_text = "$%d -- %s" % (product.price, product.description)
 
             field = forms.IntegerField(
                 label=product.name,
                 help_text=help_text,
             )
-        _ProductsForm.base_fields[field_name(product)] = field
+            cls.base_fields[cls.field_name(product)] = field
 
-    return _ProductsForm
+    @classmethod
+    def initial_data(cls, product_quantities):
+        initial = {}
+        for product, quantity in product_quantities:
+            initial[cls.field_name(product)] = quantity
+
+        return initial
+
+    def product_quantities(self):
+        for name, value in self.cleaned_data.items():
+            if name.startswith(self.PRODUCT_PREFIX):
+                product_id = int(name[len(self.PRODUCT_PREFIX):])
+                yield (product_id, value, name)
+
+
+def ProductsForm(products):
+    ''' Produces an appropriate _ProductsForm subclass for the given render
+    type. '''
+
+    if True:
+        class ProductsForm(_QuantityBoxProductsForm):
+            pass
+
+    ProductsForm.set_fields(products)
+    return ProductsForm
 
 
 class ProfileForm(forms.ModelForm):