Add integer-specific grid filter

this was necessary for smarter handling of "invalid" input, e.g. '.645' is not
a good value when querying integer fields

tailbone/grids/core.py

@@ -416,7 +416,7 @@ class Grid(object):
             elif isinstance(column.type, sa.Numeric):
                 factory = gridfilters.AlchemyNumericFilter
             elif isinstance(column.type, sa.Integer):
-                factory = gridfilters.AlchemyNumericFilter
+                factory = gridfilters.AlchemyIntegerFilter
             elif isinstance(column.type, sa.Boolean):
                 # TODO: check column for nullable here?
                 factory = gridfilters.AlchemyNullableBooleanFilter

tailbone/grids/filters.py

@@ -460,6 +460,18 @@ class AlchemyNumericFilter(AlchemyGridFilter):
         return super(AlchemyNumericFilter, self).filter_less_equal(query, value)
 
 
+class AlchemyIntegerFilter(AlchemyNumericFilter):
+    """
+    Integer filter for SQLAlchemy.
+    """
+
+    def value_invalid(self, value):
+        if value:
+            if not value.isdigit():
+                return True
+        return False
+
+
 class AlchemyBooleanFilter(AlchemyGridFilter):
     """
     Boolean filter for SQLAlchemy.