Expression.Coalesce Method (Expression, Expression)


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Creates a BinaryExpression that represents a coalescing operation.

Namespace:   System.Linq.Expressions
Assembly:  System.Core (in System.Core.dll)

public static BinaryExpression Coalesce(
	Expression left,
	Expression right


Type: System.Linq.Expressions.Expression

An Expression to set the Left property equal to.

Type: System.Linq.Expressions.Expression

An Expression to set the Right property equal to.

Return Value

Type: System.Linq.Expressions.BinaryExpression

A BinaryExpression that has the NodeType property equal to Coalesce and the Left and Right properties set to the specified values.

Exception Condition

left or right is null.


The Type property of left does not represent a reference type or a nullable value type.


left.Type and right.Type are not convertible to each other.

The Method property of the resulting BinaryExpression is null and both IsLifted and IsLiftedToNull are set to false. The Type property is equal to the result type of the coalescing operation. The Conversion property is null.

The following rules determine the result type:

  • If left.Type represents a nullable type and right.Type is implicitly convertible to the corresponding non-nullable type, the result type is the non-nullable equivalent of left.Type.

  • Otherwise, if right.Type is implicitly convertible to left.Type, the result type is left.Type.

  • Otherwise, if the non-nullable equivalent of left.Type is implicitly convertible to right.Type, the result type is right.Type.

Universal Windows Platform
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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