fix: add render_percent() method for Grid

also shortcut for grid.set_renderer()

src/wuttaweb/grids/base.py

@@ -612,6 +612,7 @@ class Grid:
         * ``'date'`` -> :meth:`render_date()`
         * ``'datetime'`` -> :meth:`render_datetime()`
         * ``'quantity'`` -> :meth:`render_quantity()`
+        * ``'percent'`` -> :meth:`render_percent()`
 
         Renderer overrides are tracked via :attr:`renderers`.
         """
@@ -622,6 +623,7 @@ class Grid:
             'date': self.render_date,
             'datetime': self.render_datetime,
             'quantity': self.render_quantity,
+            'percent': self.render_percent,
         }
 
         if renderer in builtins:
@@ -1884,6 +1886,20 @@ class Grid:
         dt = getattr(obj, key)
         return self.app.render_datetime(dt)
 
+    def render_percent(self, obj, key, value, **kwargs):
+        """
+        Column renderer for percentage values.
+
+        This calls
+        :meth:`~wuttjamaican:wuttjamaican.app.AppHandler.render_percent()`
+        for the return value.
+
+        This is not used automatically but you can use it explicitly::
+
+            grid.set_renderer('foo', 'percent')
+        """
+        return self.app.render_percent(value, **kwargs)
+
     def render_quantity(self, obj, key, value):
         """
         Column renderer for quantity values.

tests/grids/test_base.py

@@ -1409,6 +1409,24 @@ class TestGrid(WebTestCase):
         value = decimal.Decimal('-42.42')
         self.assertEqual(grid.render_currency(obj, 'foo', value), '($42.42)')
 
+    def test_render_percent(self):
+        grid = self.make_grid(columns=['foo', 'bar'])
+        obj = MagicMock()
+
+        # null
+        self.assertEqual(grid.render_percent(obj, 'foo', None), "")
+
+        # typical
+        self.assertEqual(grid.render_percent(obj, 'foo', 12.3419), '12.34 %')
+
+        # more decimal places
+        self.assertEqual(grid.render_percent(obj, 'foo', 12.3419, decimals=3), '12.342 %')
+        self.assertEqual(grid.render_percent(obj, 'foo', 12.3419, decimals=4), '12.3419 %')
+
+        # negative
+        self.assertEqual(grid.render_percent(obj, 'foo', -12.3419), '(12.34 %)')
+        self.assertEqual(grid.render_percent(obj, 'foo', -12.3419, decimals=3), '(12.342 %)')
+
     def test_render_quantity(self):
         grid = self.make_grid(columns=['foo', 'bar'])
         obj = MagicMock()