c# - 表达式 `t => (t.SomeProperty As Object)` 指的是方法，而不是属性

Question

我在一些代码中创建了这个表达式:

t => (t.SomeProperty As Object)

现在我试图通过这个小片段(很长一段时间从互联网上获得)来获取属性名称(SomeProperty):

    public static PropertyInfo GetPropertyInfo<TSource, TProperty>
        (TSource source, Expression<Func<TSource, TProperty>> propertyLambda) {
        var type = typeof(TSource);

        var member = propertyLambda.Body as MemberExpression;
        if (member == null)
            throw new ArgumentException($"Expression '{propertyLambda}' refers to a method, not a property.");

        var propInfo = member.Member as PropertyInfo;
        if (propInfo == null)
            throw new ArgumentException($"Expression '{propertyLambda}' refers to a field, not a property.");

        if (type != propInfo.ReflectedType && !type.IsSubclassOf(propInfo.ReflectedType))
            throw new ArgumentException($"Expresion '{propertyLambda}' refers to a property that is not from type {type}.");

        return propInfo;
    }

但是如您所知，propertyLambda.Body as MemberExpression 始终为 null，原因是:t => (t.Some1 As Object) 不是属性引用.在这种情况下，有什么方法可以获取属性名称吗？

Answer 1

C# as 运算符转换为 Expression.TypeAs , 和 C# 转换运算符转换为 Expression.Convert或 Expression.ConvertChecked .如您所见，它们都是 UnaryExpression 类型，因此您可以使用 Operand 提取操作数表达式属性(property)。您可以在循环中执行此操作以支持多次转换。

付诸行动，替换

var member = propertyLambda.Body as MemberExpression;

与

var operand = propertyLambda.Body;
while (operand.NodeType == ExpressionType.TypeAs || operand.NodeType == ExpressionType.Convert || operand.NodeType == ExpressionType.ConvertChecked)
    operand = ((UnaryExpression)operand).Operand;
var member = operand as MemberExpression;