Add initial support for "variance" inventory batch mode

probably incomplete yet; needs testing

tailbone/views/inventory.py

@@ -97,6 +97,9 @@ class InventoryBatchView(BatchMasterView):
     # set to False to disable "zero all" batch count mode
     allow_zero_all = True
 
+    # set to False to disable "variance" batch count mode
+    allow_variance = True
+
     # set to False to prevent exposing case fields for user input,
     # when the batch count mode is "adjust only"
     allow_adjustment_cases = True
@@ -215,6 +218,9 @@ class InventoryBatchView(BatchMasterView):
         if not self.allow_zero_all or not self.request.has_perm('{}.create.zero'.format(permission_prefix)):
             if hasattr(self.enum, 'INVENTORY_MODE_ZERO_ALL'):
                 modes.pop(self.enum.INVENTORY_MODE_ZERO_ALL, None)
+        if not self.allow_variance or not self.request.has_perm('{}.create.variance'.format(permission_prefix)):
+            if hasattr(self.enum, 'INVENTORY_MODE_VARIANCE'):
+                modes.pop(self.enum.INVENTORY_MODE_VARIANCE, None)
         return modes
 
     def configure_form(self, f):
@@ -284,10 +290,11 @@ class InventoryBatchView(BatchMasterView):
         if batch.executed:
             return self.redirect(self.get_action_url('view', batch))
 
-        form = forms.Form(schema=DesktopForm(), request=self.request)
+        schema = DesktopForm().bind(session=self.Session())
+        form = forms.Form(schema=schema, request=self.request)
         if form.validate(newstyle=True):
 
-            product = self.Session.merge(form.validated['product'])
+            product = self.Session.query(model.Product).get(form.validated['product'])
             row = model.InventoryBatchRow()
             row.product = product
             row.upc = form.validated['upc']
@@ -297,6 +304,7 @@ class InventoryBatchView(BatchMasterView):
             row.case_quantity = form.validated['case_quantity']
             row.cases = form.validated['cases']
             row.units = form.validated['units']
+            self.handler.capture_current_units(row)
             self.handler.add_row(batch, row)
             description = make_full_description(form.validated['brand_name'],
                                                 form.validated['description'],
@@ -610,6 +618,9 @@ class InventoryBatchView(BatchMasterView):
         if cls.allow_zero_all:
             config.add_tailbone_permission(permission_prefix, '{}.create.zero'.format(permission_prefix),
                                            "Create new {} with 'zero' mode".format(model_title))
+        if cls.allow_variance:
+            config.add_tailbone_permission(permission_prefix, '{}.create.variance'.format(permission_prefix),
+                                           "Create new {} with 'variance' mode".format(model_title))
 
         # row UPC lookup, for desktop
         config.add_route('{}.desktop_lookup'.format(route_prefix), '{}/{{{}}}/desktop-form/lookup'.format(url_prefix, model_key))
@@ -648,9 +659,24 @@ class InventoryForm(colander.MappingSchema):
     units = colander.SchemaNode(colander.Decimal(), missing=colander.null)
 
 
+# TODO: this is a stopgap measure to fix an obvious bug, which exists when the
+# session is not provided by the view at runtime (i.e. when it was instead
+# being provided by the type instance, which was created upon app startup).
+@colander.deferred
+def valid_product(node, kw):
+    session = kw['session']
+    def validate(node, value):
+        product = session.query(model.Product).get(value)
+        if not product:
+            raise colander.Invalid(node, "Product not found")
+        return product.uuid
+    return validate
+
+
 class DesktopForm(colander.Schema):
 
-    product = colander.SchemaNode(forms.types.ProductType())
+    product = colander.SchemaNode(colander.String(),
+                                  validator=valid_product)
 
     upc = colander.SchemaNode(forms.types.GPCType())