ConnectionStringsExpressionEditor.EvaluateExpression Method

Definition

Namespace:

System.Web.UI.Design

Assembly:

System.Design.dll

Evaluates a connection string expression and provides the design-time value for a control property.

public:
 override System::Object ^ EvaluateExpression(System::String ^ expression, System::Object ^ parseTimeData, Type ^ propertyType, IServiceProvider ^ serviceProvider);

public override object EvaluateExpression (string expression, object parseTimeData, Type propertyType, IServiceProvider serviceProvider);

override this.EvaluateExpression : string * obj * Type * IServiceProvider -> obj

Public Overrides Function EvaluateExpression (expression As String, parseTimeData As Object, propertyType As Type, serviceProvider As IServiceProvider) As Object

Parameters

expression

String

A connection string expression to evaluate. The expression does not include the ConnectionStrings expression prefix.

parseTimeData

Object

An object containing additional parsing information for evaluating the expression.

propertyType

Type

The type of the control property.

serviceProvider

IServiceProvider

A service provider implementation supplied by the designer host, used to obtain additional design-time services.

Returns

Object

The object referenced by the evaluated expression string if the expression evaluation succeeded; otherwise, null.

Remarks

The EvaluateExpression method looks up the connection name and type specified by expression, and then returns the connection.

The visual designer uses the EvaluateExpression method to evaluate a connection string expression and provide the design-time value for an associated control property. The visual designer uses the ConnectionStringsExpressionBuilder.ParseExpression method to parse the expression string at design time, and then calls the EvaluateExpression method with the parsed expression data. The visual designer uses the evaluated expression result to assign control property values that are rendered on the design surface.

At run time, the page parser uses the EvaluateExpression and GetCodeExpression methods of the corresponding ConnectionStringsExpressionBuilder implementation to evaluate an expression and provide the run-time value for an associated control property.

See also

• ExpressionBuilder
• ConnectionStringsExpressionBuilder