Add new 'bytestring' filter for grids that need it

For now, must explicitly request the filter, nothing will use it by default

tailbone/newgrids/filters.py

@@ -179,12 +179,15 @@ class GridFilter(object):
         current verb/value by default.
         """
         verb = verb or self.verb
-        value = value if value is not UNSPECIFIED else self.value
+        value = self.get_value(value)
         filtr = getattr(self, 'filter_{0}'.format(verb), None)
         if not filtr:
             raise ValueError("Unknown filter verb: {0}".format(repr(verb)))
         return filtr(data, value)
 
+    def get_value(self, value=UNSPECIFIED):
+        return value if value is not UNSPECIFIED else self.value
+
     def filter_is_any(self, data, value):
         """
         Special no-op filter which does no actual filtering.  Useful in some
@@ -300,7 +303,7 @@ class AlchemyStringFilter(AlchemyGridFilter):
         if value is None or value == '':
             return query
         return query.filter(sa.and_(
-            *[self.column.ilike('%{0}%'.format(v)) for v in value.split()]))
+            *[self.column.ilike('%{}%'.format(v)) for v in value.split()]))
 
     def filter_does_not_contain(self, query, value):
         """
@@ -318,6 +321,45 @@ class AlchemyStringFilter(AlchemyGridFilter):
         ))
 
 
+class AlchemyByteStringFilter(AlchemyStringFilter):
+    """
+    String filter for SQLAlchemy, which encodes value as bytestring before
+    passing it along to the query.  Useful when querying certain databases
+    (esp. via FreeTDS) which like to throw the occasional segfault...
+    """
+    value_encoding = 'utf-8'
+
+    def get_value(self, value=UNSPECIFIED):
+        value = super(AlchemyByteStringFilter, self).get_value(value)
+        if isinstance(value, unicode):
+            value = value.encode(self.value_encoding)
+        return value
+
+    def filter_contains(self, query, value):
+        """
+        Filter data with a full 'ILIKE' query.
+        """
+        if value is None or value == '':
+            return query
+        return query.filter(sa.and_(
+            *[self.column.ilike(b'%{}%'.format(v)) for v in value.split()]))
+
+    def filter_does_not_contain(self, query, value):
+        """
+        Filter data with a full 'NOT ILIKE' query.
+        """
+        if value is None or value == '':
+            return query
+
+        # When saying something is 'not like' something else, we must also
+        # include things which are nothing at all, in our result set.
+        return query.filter(sa.or_(
+            self.column == None,
+            sa.and_(
+                *[~self.column.ilike(b'%{}%'.format(v)) for v in value.split()]),
+        ))
+
+
 class AlchemyNumericFilter(AlchemyGridFilter):
     """
     Numeric filter for SQLAlchemy.