Question

例如，假设我有一个方法将以下内容作为参数：

Expression<Func<T, object>> path

如何确定表达式中指定的“对象”的类型？更具体地说，我想确定它是否是集合类型（例如IEnumerable）

Answer 1

你已经在使用泛型，为什么不一直走？

void GetMemberType<TArg, TProperty>(Expression<Func<TArg, TProperty>> path)
{
    // Get the member ...
    var member = path.Body as MemberExpression;

    // ... Do whatever you want with the member ...

    // Now get the type
    var memberType = typeof(TProperty);
}

Answer 2

或者，您可以执行以下操作（与通用类型参数更加一致）：

// Get your expression
// (probably already provided as an arg to one of your methods, I'm willing to bet)
Expression<Func<T, object>> path = ...

var memberExpr = path.Body as MemberExpression;
var member = memberExpr.Member;

Type type;

if (member is FieldInfo)
{
    var field = member as FieldInfo;
    type = field.FieldType;
}

if (member is PropertyInfo)
{
    var property = member as PropertyInfo;
    type = property.PropertyType;
}

Answer 3

Expression.Type将回答这个问题（表达式的“结果”类型）。

要深入挖掘并且更普遍，您需要考虑不同的可能性，具体取决于Expression实例的实际，运行时，类型 - 您实际拥有的subtypes of Expression中的哪一个。

如何找出Expression指定的类型？

3 个答案: