LambdaValue<TResult> Class

Reference

Definition

Namespace:: System.Activities.Expressions

Assembly:: System.Activities.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Represents a lambda expression used as an r-value, which supports binding of In arguments.

generic <typename TResult>
public ref class LambdaValue sealed : System::Activities::CodeActivity<TResult>, System::Activities::XamlIntegration::IValueSerializableExpression

public sealed class LambdaValue<TResult> : System.Activities.CodeActivity<TResult>, System.Activities.XamlIntegration.IValueSerializableExpression

type LambdaValue<'Result> = class
    inherit CodeActivity<'Result>
    interface IValueSerializableExpression

Public NotInheritable Class LambdaValue(Of TResult)
Inherits CodeActivity(Of TResult)
Implements IValueSerializableExpression

Type Parameters

TResult

The type of value returned by the expression.

Inheritance: Object

Activity

ActivityWithResult

Activity<TResult>

CodeActivity<TResult>
LambdaValue<TResult>

Implements: IValueSerializableExpression

Remarks

LambdaValue<TResult> is used for lambda expressions specified in code and cannot be serialized to XAML. If an attempt to serialize a workflow that contains a LambdaValue<TResult> is made, a LambdaSerializationException is thrown. If the containing workflow requires XAML serialization, use VisualBasicValue<TResult> or use ExpressionServices to convert the LambdaValue<TResult> to a format that can be serialized.

This activity uses the LINQ to Entity provider to evaluate LINQ expressions. Any LINQ expressions used with this activity must be evaluatable by the ADO.Net Entity Data Model. For example, LINQ expressions cannot be used to reference activities, variables, or arguments of the workflow itself.

Constructors

LambdaValue<TResult>(Expression<Func<ActivityContext,TResult>>)

Initializes a new instance of the LambdaValue<TResult> class using the specified expression.

Properties

CacheId	Gets the identifier of the cache that is unique within the scope of the workflow definition. (Inherited from Activity)
Constraints	Gets a collection of Constraint activities that can be configured to provide validation for the Activity. (Inherited from Activity)
DisplayName	Gets or sets an optional friendly name that is used for debugging, validation, exception handling, and tracking. (Inherited from Activity)
Id	Gets an identifier that is unique in the scope of the workflow definition. (Inherited from Activity)
Implementation	Not supported. (Inherited from CodeActivity<TResult>)
ImplementationVersion	Gets or sets the implementation version of the activity. (Inherited from CodeActivity<TResult>)
Result	Gets or sets the result argument for the Activity<TResult>. (Inherited from Activity<TResult>)
ResultType	When implemented in a derived class, gets the type of an activity OutArgument. (Inherited from ActivityWithResult)

Methods

CacheMetadata(ActivityMetadata)	Not implemented. Use CacheMetadata(CodeActivityMetadata) instead. (Inherited from CodeActivity<TResult>)
CacheMetadata(CodeActivityMetadata)	Creates and validates a description of the activity's arguments, variables, child activities, and activity delegates. (Inherited from CodeActivity<TResult>)
CanConvertToString(IValueSerializerContext)	This method always returns `true` and is used in conjunction with ConvertToString(IValueSerializerContext) to provide descriptive error messages when an attempt is made to serialize this activity to XAML.
ConvertToString(IValueSerializerContext)	Throws a LambdaSerializationException, and is used in conjunction with CanConvertToString(IValueSerializerContext) to provide descriptive error messages when an attempt is made to serialize this activity to XAML.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
Execute(CodeActivityContext)	When implemented in a derived class, performs the execution of the activity. (Inherited from CodeActivity<TResult>)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetType()	Gets the Type of the current instance. (Inherited from Object)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
OnCreateDynamicUpdateMap(UpdateMapMetadata, Activity)	Raises an event when creating a map for the dynamic update. (Inherited from CodeActivity<TResult>)
ShouldSerializeDisplayName()	Indicates whether the DisplayName property should be serialized. (Inherited from Activity)
ToString()	Returns a String that contains the Id and DisplayName of the Activity. (Inherited from Activity)

Applies to

แชร์ผ่าน