這是我使用的代碼:我有了一個模型無法投型「System.Linq.Expressions.InstanceMethodCallExpressionN」的對象鍵入「System.Linq.Expressions.MemberExpression
Private Function ExpresionNullable(contenedor As ParameterExpression, prop As String) As MemberExpression
Dim member As Expression
member = Expression.PropertyOrField(contenedor, prop)
Dim typeIfNullable As Type = Nullable.GetUnderlyingType(member.Type)
If typeIfNullable IsNot Nothing Then
Dim callexpression As MethodCallExpression = Expression.Call(member, "GetValueOrDefault", Type.EmptyTypes)
member = callexpression
End If
Return member
End Function
此屬性:Public Property price As Decimal?
,當我嘗試使用此:exprPropiedad = Expression.Property(exprPropiedad, prop)
我得到一個錯誤,因爲它是允許空值,所以我發現該函數,但有問題將MethodCallExpression投向MethodCallExpression的。
你可以提供代碼在哪裏調用ExpresionNullable?你能解釋你想做什麼嗎? –