Stop using sa-filters for basic grid sorting

this just breaks if we need to use "aliased" models e.g. when sorting
and/or filtering by Product "regular price" column and similar.  so
now sorting more like we always used to, except for multi-column.

nb. this still assumes callers use `Grid.make_sorter()` when declaring
the sorters.  if caller must specify more custom/explicit sort logic
then it likely will not work and we'll have to add a workaround to
allow avoiding the common logic..but that's another day

tailbone/grids/core.py

@@ -30,7 +30,6 @@ import logging
 
 import sqlalchemy as sa
 from sqlalchemy import orm
-from sa_filters import apply_sort
 
 from rattail.db.types import GPCType
 from rattail.util import prettify, pretty_boolean, pretty_quantity
@@ -1235,29 +1234,29 @@ class Grid(object):
         # TODO: is there a better way to check for SA sorting?
         if self.model_class:
 
-            # convert sort settings into a 'sortspec' for use with sa-filters
-            full_spec = []
+            # collect actual column sorters for order_by clause
+            sorters = []
             for sorter in self.active_sorters:
                 sortkey = sorter['field']
-                sortdir = sorter['order']
                 sortfunc = self.sorters.get(sortkey)
-                if sortfunc:
-                    spec = {
-                        'sortkey': sortkey,
-                        'model': sortfunc._class.__name__,
-                        'field': sortfunc._column.key,
-                        'direction': sortdir or 'asc',
-                    }
-                    full_spec.append(spec)
+                if not sortfunc:
+                    log.warning("unknown sorter: %s", sorter)
+                    continue
 
-            # apply joins needed for this sort spec
-            for spec in full_spec:
-                sortkey = spec['sortkey']
+                # join appropriate model if needed
                 if sortkey in self.joiners and sortkey not in self.joined:
                     data = self.joiners[sortkey](data)
                     self.joined.add(sortkey)
 
-            return apply_sort(data, full_spec)
+                # add column/dir to collection
+                sortdir = sorter['order']
+                sorters.append(getattr(sortfunc._column, sortdir)())
+
+            # apply sorting to query
+            if sorters:
+                data = data.order_by(*sorters)
+
+            return data
 
         else:
             # not a SQLAlchemy grid, custom sorter

tailbone/views/products.py

@@ -160,12 +160,6 @@ class ProductView(MasterView):
         'inventory_on_order',
     ]
 
-    # same, but for prices
-    RegularPrice = orm.aliased(model.ProductPrice)
-    CurrentPrice = orm.aliased(model.ProductPrice)
-    SalePrice = orm.aliased(model.ProductPrice)
-    TPRPrice = orm.aliased(model.ProductPrice)
-
     def __init__(self, request):
         super().__init__(request)
         self.expose_label_printing = self.rattail_config.getbool(
@@ -332,28 +326,34 @@ class ProductView(MasterView):
         g.set_joiner('family', lambda q: q.outerjoin(model.Family))
         g.set_filter('family', model.Family.name)
 
+        # regular_price
         g.set_label('regular_price', "Reg. Price")
+        RegularPrice = orm.aliased(model.ProductPrice)
         g.set_joiner('regular_price', lambda q: q.outerjoin(
-            self.RegularPrice, self.RegularPrice.uuid == model.Product.regular_price_uuid))
-        g.set_sorter('regular_price', self.RegularPrice.price)
-        g.set_filter('regular_price', self.RegularPrice.price, label="Regular Price")
+            RegularPrice, RegularPrice.uuid == model.Product.regular_price_uuid))
+        g.set_sorter('regular_price', RegularPrice.price)
+        g.set_filter('regular_price', RegularPrice.price, label="Regular Price")
 
+        # current_price
         g.set_label('current_price', "Cur. Price")
         g.set_renderer('current_price', self.render_current_price_for_grid)
+        CurrentPrice = orm.aliased(model.ProductPrice)
         g.set_joiner('current_price', lambda q: q.outerjoin(
-            self.CurrentPrice, self.CurrentPrice.uuid == model.Product.current_price_uuid))
-        g.set_sorter('current_price', self.CurrentPrice.price)
-        g.set_filter('current_price', self.CurrentPrice.price, label="Current Price")
+            CurrentPrice, CurrentPrice.uuid == model.Product.current_price_uuid))
+        g.set_sorter('current_price', CurrentPrice.price)
+        g.set_filter('current_price', CurrentPrice.price, label="Current Price")
 
         # tpr_price
+        TPRPrice = orm.aliased(model.ProductPrice)
         g.set_joiner('tpr_price', lambda q: q.outerjoin(
-            self.TPRPrice, self.TPRPrice.uuid == model.Product.tpr_price_uuid))
-        g.set_filter('tpr_price', self.TPRPrice.price)
+            TPRPrice, TPRPrice.uuid == model.Product.tpr_price_uuid))
+        g.set_filter('tpr_price', TPRPrice.price)
 
         # sale_price
+        SalePrice = orm.aliased(model.ProductPrice)
         g.set_joiner('sale_price', lambda q: q.outerjoin(
-            self.SalePrice, self.SalePrice.uuid == model.Product.sale_price_uuid))
-        g.set_filter('sale_price', self.SalePrice.price)
+            SalePrice, SalePrice.uuid == model.Product.sale_price_uuid))
+        g.set_filter('sale_price', SalePrice.price)
 
         # suggested_price
         g.set_renderer('suggested_price', self.render_grid_suggested_price)
@@ -402,7 +402,9 @@ class ProductView(MasterView):
         return "${:0.2f}".format(cost.unit_cost)
 
     def render_price(self, product, field):
-        if not product.not_for_sale:
+        # TODO: previously this rendered null (empty string) if
+        # product was marked "not for sale" - but why? important?
+        #if not product.not_for_sale:
         price = product[field]
         if price:
             return self.products_handler.render_price(price)