问题
Is there a way to supply a name to a function that then returns the value of either the field or property on a given object with that name? I tried to work around it with the null-coalesce operator, but apparently that doesn't like different types (which is also a bit weird to me because null is null). I could separate it it out into if nulls, but there has to be a better way to do this. Here is my function, and the two lines with Comparison
objects don't compile, but I will leave them in there to show what I am trying to do.
private void SortByMemberName<T>(List<T> list, string memberName, bool ascending)
{
Type type = typeof (T);
MemberInfo info = type.GetField(memberName) ?? type.GetProperty(memberName);
if (info == null)
{
throw new Exception("Member name supplied is neither a field nor property of type " + type.FullName);
}
Comparison<T> asc = (t1, t2) => ((IComparable) info.GetValue(t1)).CompareTo(info.GetValue(t2));
Comparison<T> desc = (t1, t2) => ((IComparable) info.GetValue(t2)).CompareTo(info.GetValue(t1));
list.Sort(ascending ? asc : desc);
}
I have heard of something called dynamic linq that could be used, but for the sake of learning, I am doing it my way.
回答1:
Change this line:
MemberInfo info = type.GetField(memberName) ?? type.GetProperty(memberName);
to this:
MemberInfo info = type.GetField(memberName) as MemberInfo ??
type.GetProperty(memberName) as MemberInfo;
because there's no implicit cast to the base class when using the ternary operator like that. The ternary requires that the types of all outputs be the same.
来源:https://stackoverflow.com/questions/16305529/c-sharp-reflection-get-field-or-property-by-name