fix: improve built-in grid renderer logic

- add `render_batch_id()`
- allow kwargs for `render_currency()`
- caller may specify built-in renderer w/ string identifier

src/wuttaweb/grids/base.py

@@ -389,7 +389,6 @@ class Grid:
         self.key = key
         self.data = data
         self.labels = labels or {}
-        self.renderers = renderers or {}
         self.row_class = row_class
         self.actions = actions or []
         self.linked_columns = linked_columns or []
@@ -399,6 +398,10 @@ class Grid:
         self.app = self.config.get_app()
 
         self.set_columns(columns or self.get_columns())
+        self.renderers = {}
+        if renderers:
+            for key, val in renderers.items():
+                self.set_renderer(key, val)
         self.set_default_renderers()
         self.set_tools(tools)
 
@@ -593,8 +596,29 @@ class Grid:
            grid = Grid(request, columns=['foo', 'bar'])
            grid.set_renderer('foo', render_foo)
 
+        For convenience, in lieu of a renderer callable, you may
+        specify one of the following strings, which will be
+        interpreted as a built-in renderer callable, as shown below:
+
+        * ``'batch_id'`` -> :meth:`render_batch_id()`
+        * ``'boolean'`` -> :meth:`render_boolean()`
+        * ``'currency'`` -> :meth:`render_currency()`
+        * ``'datetime'`` -> :meth:`render_datetime()`
+        * ``'quantity'`` -> :meth:`render_quantity()`
+
         Renderer overrides are tracked via :attr:`renderers`.
         """
+        builtins = {
+            'batch_id': self.render_batch_id,
+            'boolean': self.render_boolean,
+            'currency': self.render_currency,
+            'datetime': self.render_datetime,
+            'quantity': self.render_quantity,
+        }
+
+        if renderer in builtins:
+            renderer = builtins[renderer]
+
         if kwargs:
             renderer = functools.partial(renderer, **kwargs)
         self.renderers[key] = renderer
@@ -1759,6 +1783,20 @@ class Grid:
     # rendering methods
     ##############################
 
+    def render_batch_id(self, obj, key, value):
+        """
+        Column renderer for batch ID values.
+
+        This is not used automatically but you can use it explicitly::
+
+            grid.set_renderer('foo', 'batch_id')
+        """
+        if value is None:
+            return ""
+
+        batch_id = int(value)
+        return f'{batch_id:08d}'
+
     def render_boolean(self, obj, key, value):
         """
         Column renderer for boolean values.
@@ -1774,7 +1812,7 @@ class Grid:
         """
         return self.app.render_boolean(value)
 
-    def render_currency(self, obj, key, value):
+    def render_currency(self, obj, key, value, **kwargs):
         """
         Column renderer for currency values.
 
@@ -1784,9 +1822,10 @@ class Grid:
 
         This is not used automatically but you can use it explicitly::
 
-            grid.set_renderer('foo', grid.render_currency)
+            grid.set_renderer('foo', 'currency')
+            grid.set_renderer('foo', 'currency', scale=4)
         """
-        return self.app.render_currency(value)
+        return self.app.render_currency(value, **kwargs)
 
     def render_datetime(self, obj, key, value):
         """

tests/grids/test_base.py

@@ -208,6 +208,11 @@ class TestGrid(WebTestCase):
         self.assertIsNot(grid.renderers['foo'], render2)
         self.assertEqual(grid.renderers['foo'](None, None, None), 42)
 
+        # can use built-in string shortcut
+        grid.set_renderer('foo', 'quantity')
+        obj = MagicMock(foo=42.00)
+        self.assertEqual(grid.renderers['foo'](obj, 'foo', 42.00), '42')
+
     def test_set_default_renderer(self):
         model = self.app.model
 
@@ -1343,6 +1348,17 @@ class TestGrid(WebTestCase):
     # rendering methods
     ##############################
 
+    def test_render_batch_id(self):
+        grid = self.make_grid(columns=['foo', 'bar'])
+
+        # null
+        obj = MagicMock(foo=None)
+        self.assertEqual(grid.render_batch_id(obj, 'foo', None), "")
+
+        # int
+        obj = MagicMock(foo=42)
+        self.assertEqual(grid.render_batch_id(obj, 'foo', 42), "00000042")
+
     def test_render_boolean(self):
         grid = self.make_grid(columns=['foo', 'bar'])