HomeDev GuideAPI Reference
Dev GuideAPI ReferenceUser GuideGitHubNuGetDev CommunityDoc feedbackLog In
GitHubNuGetDev CommunityDoc feedback

Business Foundation (BF) has a unified object model for filtering and sorting rows and entity objects. The filter is analogous to the SQL **WHERE** clause. The filter contains a _filter pattern_, which evaluates to a Boolean value and is tested for each element in the collection. Elements that fail the test are omitted from the result collection.

The sorting is analogous to the SQL **ORDER BY** clause. The sorting element contains field name and direction.


By default, the top block is **AND**.

Classes in this topic are available in the Mediachase.BusinessFoundation.Data namespace.

## Create simple filters

**Example: **Returns elements where the key is 1.

**Example:** Returns elements where key contains keyword.

**Example:** Returns elements where **StartDate** is between two days.

## Logical blocks

You can create logical blocks using the OrBlockFilterElement and AndBlockFilterElement classes.

**Example:** Return elements where Extension is txt or empty string

## Templates

BF supports template values in the filter and sorting expressions, using the template directives (mentioned below). Also, you can use the ResolveAll and Resolve methods to resolve custom template strings in your code.

**Template Directive:**


For example, the string **: {DateTime:Today}** is converted to the current date.

To register a new template source, call AddSource of the TemplateResolver class, passing template source name and template source class.

DateTimeTemplateSource, included in BF, can convert template value strings to real date time.

**Supported template values:** Today, TodayStart, Yesterday, YesterdayStart, ThisWeek, ThisWeekStart, ThisMonth, ThisMonthStart, LastMonth, LastMonthStart, ThisYear, ThisYearStart, LastYear, LastYearStart, TodayEnd, YesterdayEnd, ThisWeekEnd, LastWeekEnd, ThisMonthEnd, ThisYearEnd, LastMonthEnd, ThisYearEnd, LastYearEnd.

To create a custom template source, create a class that implements the ITemplateSource interface. Also, implement the GetValue method.

## Template value in filters

**Example:** Using template value in filter expression

## Sort

Use the SortingElement class to define sorting element.

**Example:** Sorting output collection by IsProject columns, ascending