Operating with RadListView FilterExpressions Manually

As of Q1 2010 Telerik RadListView has build-in server-side API for creating and applying filter expressions. It gives you the ability to filter the data displayed in a RadListView control without creating complex database queries.

Adding FilterExpressions for RadListView

RadListView provides an intuitive way for building filter expressions through its FilterExpressions Add() and BuildExpression() methods listed below:

Method	Return Type	Parameters	Description
Add()	RadListViewFilterExpressionCollection	RadListViewFilterExpression	Adds the specified as an argument filter expression to the RadListView FilterExpressions collection.
BuildExpression()	RadListViewFilterExpressionCollection	Action (optional)	A helper method for building filter expression hierarchy in a fluent like manner.

RadListView FilterExpression Types

The following table describes all filter expression types you can use when building RadListView FilterExpressions:

FilterExpression type	Description
RadListViewContainsFilterExpression	Represents Contains RadListView filter expression.
RadListViewGreaterThanFilterExpression	Represents GreaterThan RadListView filter expression where T is the type of the field on which filter will be applied.
RadListViewGreaterThanOrEqualToFilterExpression	Represents GreaterThan or EqualTo RadListView filter expression where T is the type of the field on which filter will be applied.
RadListViewGroupFilterExpression	Represents a group of filter expressions.
RadListViewIsEmptyFilterExpression	Represents IsEmpty RadListView filter expression.
RadListViewIsNotEmptyFilterExpression	Represents IsEmpty RadListView filter expression.
RadListViewIsNotNullFilterExpression	Represents IsNotNull RadListView filter expression.
RadListViewIsNullFilterExpression	Represents IsNull RadListView filter expression.
RadListViewLessThanFilterExpression	Represents LessThan RadListView filter expression where T is the type of the field on which filter will be applied.
RadListViewLessThanOrEqualToFilterExpression	Represents LessThan or EqualTo RadListView filter expression where T is the type of the field on which filter will be applied.
RadListViewEqualToFilterExpression	Represents EqualTo RadListView filter expression where T is the type of the field on which filter will be applied.
RadListViewNotEqualToFilterExpression	Represents NotEqualTo RadListView filter expression where T is the type of the field on which filter will be applied.
RadListViewStartsWithFilterExpression	Represents StartsWith RadListView filter expression.
RadListViewEndsWithFilterExpression	Represents EndsWith RadListView filter expression.

Here are some examples illustrating how you can use the above types to create filter expressions and add them to the RadListView FilterExpressions collection:

C#

RadListViewContainsFilterExpression expression1 = new
RadListViewContainsFilterExpression("CustomerID");
expression1.CurrentValue =
"ALFKI";
RadListView1.FilterExpressions.Add(expression1);
RadListView1.FilterExpressions.Add(new
RadListViewGreaterThanFilterExpression<DateTime>("ShippedDate") {
CurrentValue = DateTime.Parse("7/10/1996") });
RadListView1.FilterExpressions.Add(
    new
RadListViewGroupFilterExpression(RadListViewGroupFilterOperator.Or)
    {
        Expressions =
        {
            new
RadListViewGreaterThanFilterExpression<DateTime>("ShippedDate"){CurrentValue
= DateTime.Parse("7/10/1996")},
            new
RadListViewEqualToFilterExpression<int>("OrderID"){CurrentValue =
42}
        }
    }
);

VB

Dim expression1 As RadListViewContainsFilterExpression = New RadListViewContainsFilterExpression("CustomerID")
expression1.CurrentValue = "ALFKI"
RadListView1.FilterExpressions.Add(expression1)
RadListView1.FilterExpressions.Add(New RadListViewGreaterThanFilterExpression(Of DateTime)("ShippedDate")
    With _{.CurrentValue = DateTime.Parse("7/10/1996")})
Dim group = New RadListViewGroupFilterExpression(RadListViewGroupFilterOperator.Or)
With group
    .Expressions.Add(New RadListViewGreaterThanFilterExpression(Of DateTime)("ShippedDate") With {.CurrentValue = DateTime.Parse("7/10/1996")})
    .Expressions.Add(New RadListViewEqualToFilterExpression(Of Integer)("OrderID") With {.CurrentValue = 42})
End With
RadListView1.FilterExpressions.Add(group)

BuildExpression() methods

Another possible approach for adding filter expressions to RadListView is using the BuildExpression() method and its methods listed here:

Method	Parameters	Description
Contains(string fieldName, string currentValue)	fieldName is the name of the field which will be filtered; currentValue is the value to be filtered on	Adds a Contains filter expression
EqualTo(string fieldName, T currentValue)	fieldName is the name of the field which will be filtered; currentValue is the value to be filtered on	Adds an EqualTo filter expression where T is the type of the field which will be filtered
NotEqualTo(string fieldName, T currentValue)	fieldName is the name of the field which will be filtered; currentValue is the value to be filtered on	Adds a NotEqualTo filter expression where T is the type of the field which will be filtered
GreaterThan(string fieldName, T currentValue)	fieldName is the name of the field which will be filtered; currentValue is the value to be filtered on	Adds a GreaterThan filter expression where T is the type of the field which will be filtered
GreaterThanOrEqualTo(string fieldName, T currentValue)	fieldName is the name of the field which will be filtered; currentValue is the value to be filtered on	Adds a GreaterThanOrEqualTo filter expression where T is the type of the field which will be filtered
Group(Action groupBuilder)	groupBuilder is the inner group instance	Adds a group of filter expressions
IsEmpty(string fieldName)	fieldName is the name of the field which will be filtered	Adds an IsEmpty filter expression
IsNotEmpty(string fieldName)	fieldName is the name of the field which will be filtered	Adds an IsNotEmpty filter expression
IsNull(string fieldName)	fieldName is the name of the field which will be filtered	Adds an IsNull filter expression
IsNotNull(string fieldName)	fieldName is the name of the field which will be filtered	Adds an IsNotNull filter expression
LessThan(string fieldName, T currentValue)	fieldName is the name of the field which will be filtered; currentValue is the value to be filtered on	Adds a LessThan filter expression where T is the type of the field which will be filtered
LessThanOrEqualTo(string fieldName, T currentValue)	fieldName is the name of the field which will be filtered; currentValue is the value to be filtered on	Adds a LessThanOrEqualTo filter expression where T is the type of the field which will be filtered
StartsWith(string fieldName, string currentValue)	fieldName is the name of the field which will be filtered; currentValue is the value to be filtered on	Adds a StartsWith filter
EndsWith(string fieldName, string currentValue)	fieldName is the name of the field which will be filtered; currentValue is the value to be filtered on	Adds a EndsWith filter
And()		Adds an And operator between the filter expressions on its left and right side
Or()		Adds an Or operator between the filter expressions on its left and right side

The following examples illustrate how you can use the BuildExpression() methods to create RadListView filter expressions:

C#

RadListView1.FilterExpressions.BuildExpression()
.GreaterThan("ShippedDate", DateTime.Parse("7/10/1996"))
.Or().EqualTo("OrderID", 42).Build();

VB

RadListView1.FilterExpressions.BuildExpression()
        .GreaterThan("ShippedDate", DateTime.Parse("7/10/1996"))
        .Or().EqualTo("OrderID", 42).Build()

When you are using the BuildExpression() methods to add filter expressions as shown above, you need to call the Build() at the end so the filter expressions are built and added to the RadListView FilterExpressions collection. Note that the Build() method could be called only once per expressions building. To check if the Build() method is already called, you can use the BuildExpression().IsBuild property.

C#

RadListView1.FilterExpressions
.BuildExpression(expression => expression
.GreaterThan("ShippedDate", DateTime.Parse("7/10/1996"))
.Or().EqualTo("OrderID", 42)
.And().Group(group =>
group.IsNotEmpty("ShipCountry")
.And().Contains("ShipCountry", "G")
)
);

VB

 RadListView1.FilterExpressions.BuildExpression(Function(expression As RadListViewFilterExpressionFluentBuilder)
   expression.GreaterThan("ShippedDate", DateTime.Parse("7/10/1996")) _
     .Or().EqualTo("OrderID", 42).And().Group(Function(group As RadListViewFilterExpressionFluentBuilder) _
       group.IsNotEmpty("ShipCountry").And().Contains("ShipCountry", "G")))

RadListView filter expression enumerators

RadListView supplies the following enumerators to help you build the desired filter expressions:

Enumerator	Values
RadListViewFilterFunction	Contains
	EqualTo
	GreaterThan
	GreaterThanOrEqualTo
	IsEmpty
	IsNull
	LessThan
	LessThanOrEqualTo
	NotEqualTo
	NotIsEmpty
	NotIsNull
RadListViewGroupFilterOperator	And
	Or

For a live example on how RadListView built-in filtering capabilities can be used, review the online demo here .