诀窍是：这种形式的任何表达......
obj => obj.A.B.C // etc.
...实际上只是一堆嵌套MemberExpression对象。
首先你有：
MemberExpression: obj.A.B.C
Expression: obj.A.B // MemberExpression
Member: C
评估Expression above as a MemberExpression给你：
MemberExpression: obj.A.B
Expression: obj.A // MemberExpression
Member: B
最后，上面that（在“顶部”）你有：
MemberExpression: obj.A
Expression: obj // note: not a MemberExpression
Member: A
所以很明显，解决这个问题的方法是检查Expression的财产MemberExpression直到它不再是它自己MemberExpression.
UPDATE: 看来你的问题有一个额外的旋转。您可能有一些 lambdalooks like a Func<T, int>...
p => p.Age
...但是actually a Func<T, object>;在这种情况下，编译器会将上面的表达式转换为：
p => Convert(p.Age)
调整这个问题实际上并不像看起来那么困难。看一下我更新的代码，了解一种处理方法。请注意，通过抽象代码来获取MemberExpression进入它自己的方法（TryFindMemberExpression），这种方法保持了GetFullPropertyName方法相当干净，并允许您在将来添加额外的检查——如果，也许，您发现自己面临着new您最初没有考虑到的场景 - 无需费力地阅读太多代码。
举例来说：这段代码对我有用。
// code adjusted to prevent horizontal overflow
static string GetFullPropertyName<T, TProperty>
(Expression<Func<T, TProperty>> exp)
{
MemberExpression memberExp;
if (!TryFindMemberExpression(exp.Body, out memberExp))
return string.Empty;
var memberNames = new Stack<string>();
do
{
memberNames.Push(memberExp.Member.Name);
}
while (TryFindMemberExpression(memberExp.Expression, out memberExp));
return string.Join(".", memberNames.ToArray());
}
// code adjusted to prevent horizontal overflow
private static bool TryFindMemberExpression
(Expression exp, out MemberExpression memberExp)
{
memberExp = exp as MemberExpression;
if (memberExp != null)
{
// heyo! that was easy enough
return true;
}
// if the compiler created an automatic conversion,
// it'll look something like...
// obj => Convert(obj.Property) [e.g., int -> object]
// OR:
// obj => ConvertChecked(obj.Property) [e.g., int -> long]
// ...which are the cases checked in IsConversion
if (IsConversion(exp) && exp is UnaryExpression)
{
memberExp = ((UnaryExpression)exp).Operand as MemberExpression;
if (memberExp != null)
{
return true;
}
}
return false;
}
private static bool IsConversion(Expression exp)
{
return (
exp.NodeType == ExpressionType.Convert ||
exp.NodeType == ExpressionType.ConvertChecked
);
}
Usage:
Expression<Func<Person, string>> simpleExp = p => p.FirstName;
Expression<Func<Person, string>> complexExp = p => p.Address.State.Abbreviation;
Expression<Func<Person, object>> ageExp = p => p.Age;
Console.WriteLine(GetFullPropertyName(simpleExp));
Console.WriteLine(GetFullPropertyName(complexExp));
Console.WriteLine(GetFullPropertyName(ageExp));
Output:
FirstName
Address.State.Abbreviation
Age
