.net – Linq表达式：没有为类型’MyEnum’和’System.Enum’定

我有一个枚举的问题 – MyObjectType的属性.

枚举是标准枚举

Public Enum MyEnum
  A
  B 
  C
End Enum

这是我获取表达式的方式：

Dim constantExpression As ConstantExpression
If TypeOf Value Is [Enum] Then
  constantExpression = Expression.Constant(Value,GetType([Enum]))
Else
  constantExpression = Expression.Constant(Value,Value.GetType())
End If
...
Dim expr As Expression = Nothing
Dim objectPropertyParam = Expression.Property(objectParam,objectPropertyName)

Select Case Me.Operation
  Case ComparisonOperator.Contains,ComparisonOperator.NotContains
  ...
  Case ComparisonOperator.NotEqual
  ...

  Case ComparisonOperator.Equal
    ' THE EXCEPTION IS HERE ---------------------------------------
    expr = Expression.Equal(objectPropertyParam,constantExpression)

  Case ComparisonOperator.GreatherThanOrEqual
    expr = Expression.GreaterThanOrEqual(objectPropertyParam,constantExpression)
  Case ComparisonOperator.LessThanOrEqual
    expr = Expression.LessThanOrEqual(objectPropertyParam,constantExpression)
End Select

然后发生以下异常：

The binary operator Equal is not defined for the types ‘MyEnum’ and
‘System.Enum’.

at
System.Linq.Expressions.Expression.GetEqualityComparisonOperator(ExpressionType
binaryType,String opName,Expression left,Expression right,Boolean
liftToNull) at System.Linq.Expressions.Expression.Equal(Expression
left,Expression right)

PS.

我观察到如果我这样做

expr = Expression.Equal(objectPropertyParam,Expression.Convert(constantExpression,GetType(MyEnum)))

这个Works,但是我想不要像这样规范每种类型的枚举,因为它是一个通用函数！？