Reflection: FindMembers returning empty

Question

I'm trying to list all members with a given attribute, I've implemented a method that uses FindMembers but it always return an empty collection. Can anyone tell me what I'm doing wrong?

public List<MemberInfo> GetMembers<TClass, TAttribute>()
{
    Type type = typeof(TClass);
    Type attributeType = typeof(TAttribute);
    List<MemberInfo> members = type.FindMembers(MemberTypes.All, BindingFlags.Default, Filter, null).ToList();
    return members;
}

public bool Filter(MemberInfo memberInfo, object filterCriteria)
{
    return memberInfo.IsDefined(typeof(TestAttribute));
}

[Test]
public string MethodName()
{
    return "test";
}

When it I call like this:

List<MemberInfo> members = GetMembers<TestClass, TestAttribute>();

It returns empty.

score 2 · Accepted Answer · answered Feb 14 '19 at 11:56

2

From the docs, BindingFlags.Default:

Specifies that no binding flags are defined.

You need to tell FindMembers exactly what you want, for example if you want public members that are either static or instance members:

var flags = BindingFlags.Public | BindingFlags.Static | BindingFlags.Instance;
List<MemberInfo> members = type.FindMembers(MemberTypes.All, flags, Filter, null).ToList();

As an aside, you may want to add a generic type constraint to your GetMember function to restrict the attribute type:

public List<MemberInfo> GetMember<TClass, TAttribute>() 
    where TAttribute : Attribute

answered Feb 14 '19 at 11:56

DavidG

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And if I want any kind of members? Is there an umbrella flag? – Matheus Simon Feb 14 '19 at 11:59
The only flag that's really missing from the list I show is `BindingFlags.NonPublic` which will also return private members. What else do you need? – DavidG Feb 14 '19 at 12:10

score 1 · Answer 2 · answered Feb 14 '19 at 12:04

1

You can also use GetMembers() method and then filter your result:

var members = type.GetMembers().Where(x => Attribute.IsDefined(x, typeof(TestAttribute))).ToList()

answered Feb 14 '19 at 12:04

yolo sora

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Thats a good alternative but I think its more elegant done the full reflection way. Thanks. – Matheus Simon Feb 14 '19 at 12:41

Reflection: FindMembers returning empty

2 Answers2