SearchExpression Class

SearchExpression Class

.NET Framework 4.6 and 4.5

Provides a way to search a field or fields for string values and compare them to a specified string value.

Namespace:   System.Web.UI.WebControls.Expressions
Assembly:  System.Web.Extensions (in System.Web.Extensions.dll)

Public Class SearchExpression
	Inherits ParameterDataSourceExpression


Initializes a new instance of the SearchExpression class.


Gets or sets the type of string comparison to perform.


Gets the HttpContext instance of the owner control.(Inherited from DataSourceExpression.)


Gets and sets a single field or a comma-separated list of fields to search.


Gets the data source object that is associated with the owner control.(Inherited from DataSourceExpression.)


Gets a value that indicates whether a data source expression object is tracking its view state changes.(Inherited from DataSourceExpression.)


Gets the owner control.(Inherited from DataSourceExpression.)


Gets the parameters that are associated with this DataSourceExpression object.(Inherited from ParameterDataSourceExpression.)


Gets or sets the SearchType value that determines where in the string the search occurs.


Gets an instance of the StateBag class that contains the current view state information.(Inherited from DataSourceExpression.)


Determines whether the specified object is equal to the current object.(Inherited from Object.)


Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)


Serves as the default hash function. (Inherited from Object.)


Applies a SearchExpression object to the specified IQueryable object based on the SearchType object.(Overrides DataSourceExpression.GetQueryable(IQueryable).)


Gets the Type of the current instance.(Inherited from Object.)


Loads the state of the values in the ParameterDataSourceExpression object that must be persisted.(Inherited from ParameterDataSourceExpression.)


Creates a shallow copy of the current Object.(Inherited from Object.)


Saves the current view state of the ParameterDataSourceExpression object.(Inherited from ParameterDataSourceExpression.)

System_CAPS_pubmethodSetContext(Control, HttpContext, IQueryableDataSource)

Executes the expression by using the specified owner control, context, and data source.(Inherited from ParameterDataSourceExpression.)


Marks the DataSourceExpression object so that its state will be saved in view state.(Inherited from DataSourceExpression.)


Returns a string that represents the current object.(Inherited from Object.)


Tracks view-state changes of the ParameterDataSourceExpression object so that the changes can be stored in the StateBag object for the object.(Inherited from ParameterDataSourceExpression.)


When implemented by a class, loads the previously saved view state of the data source expression object.(Inherited from DataSourceExpression.)


When implemented by a class, saves the current view state of the DataSourceExpression object.(Inherited from DataSourceExpression.)


When implemented by a class, tracks view state changes of the DataSourceExpression object so that the changes can be stored in the StateBag object for the data source expression object.(Inherited from DataSourceExpression.)

Exception Condition

The DataFields property is null (Nothing in Visual Basic)

The QueryExtender control provides the ability to filter data in a Web page by using the SearchExpression class. The SearchExpression class compares a specified string in a field or fields to a value that you supply. The expression performs a "starts with", "contains", or "ends with" search. You must specify values for the SearchType and the DataFields properties in order to indicate the type of search you want to perform and the data fields that you want to search. If the LINQ provider that you use in the QueryExtender control supports case sensitivity, you can use the ComparisonType property to enable or ignore case sensitivity.

The value to search can be provided by an ASP.NET control. To specify this, you set the ControlID property of the ControlParameter class in the SearchExpression object to the ID of a ASP.NET control. For example, if the value to search is entered in a text box, the ControlID property must be set to the ID of the text box control. You can use the SearchExpression class in combination with the other expressions that the QueryExtender supports, such as the RangeExpression filter. For example, you can search for product names that contain the string "tea" and a list price between 100 and 200.

The following example shows how to search the Name column in the Products table of the AdventureWorks database for products whose that start with the string that is specified in the SearchTextBox control. The result that is returned from the LinqDataSource control is displayed in a GridView control.

This code example is part of a larger example that is provided in Walkthrough: Filtering Data in a Web Page Using Declarative Syntax.

.NET Framework
Available since 4.0

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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