Databases Reference
In-Depth Information
filtering operators, such as “contains” or “starts with” because they are only applicable to
strings. Although this is not done in the source code accompanying this topic, real-world
applications typically have a bigger set of filter templates, implementing additional type-
specific filtering operators for numbers and dates in filter templates called
Decimal.ascx
,
Integer.ascx
, and
DateTime.ascx
. This removes the requirement for the Text filter
template to support multiple primitive data types and allows you to implement string-
specific filtering operators in this control instead.
FIGURE 13.2
Unleashed filter lookup algorithm.
Extending the MetaTable Class
The second part of the algorithm that determines which entity properties will have filter
templates generated dynamically is implemented in the
MetaTable
class, which defines a
virtual method called
GetFilteredColumns
that returns an
IEnumerable
of
MetaColumn
objects.
public class MetaTable
{
public virtual IEnumerable<MetaColumn> GetFilteredColumns();
}
The
GetFilteredColumns
method is called by the built-in
QueryableFilterRepeater
control (and by the
UnleashedFilterRepeater
) to get a list of properties that can be
filtered. For each
MetaColumn
object it returns, the repeater creates a
DynamicFilter
(or
the
UnleashedFilter
) control, which in turn calls the
CreateFilterControl
method of
the
FilterFactory
just implemented to locate and create the filter templates.
The default implementation of the
GetFilteredColumns
method in the
MetaTable
class
assumes that only properties of Boolean, ForeignKey, and Enumeration types can be
filtered. Even though the
UnleashedFilterFactory
already supports other property types,
