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如何查找表达式指定的类型?

lambda .net c#

1

DanP · 技术社区 · 15 年前

例如,假设我有一个方法,它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 )

3 回复 | 直到 15 年前

1

2

Charles 15 年前

你已经在使用仿制药了,为什么不一路走呢?

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);
}

2

1

Charles 15 年前

或者,您可以执行如下操作(这更符合您的泛型类型参数):

// 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;
}

3

0

Richard 15 年前

Expression.Type 将回答此问题(表达式的“result”类型)。

要更深入更一般地挖掘,您需要考虑不同的可能性,具体取决于 Expression 举个例子 subtypes of Expression 你真的有。