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How do I know if a property is an auto-implemented property with reflection?

So in my case I am doing an opening of a class structure using reflection. I need to find out if a property is an auto-implemented property of a PropertyInfo object. I'm guessing the reflection API doesn't expose such functionality because auto-properties are C # dependent, but are there any workarounds for this information?

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2 answers


You can check whether the method is marked get

or set

attribute CompilerGenerated

. Then you can combine this with finding a private field that is marked with an attribute CompilerGenerated

containing the property name and string "BackingField"

.

May be:



public static bool MightBeCouldBeMaybeAutoGeneratedInstanceProperty(
    this PropertyInfo info
) {
    bool mightBe = info.GetGetMethod()
                       .GetCustomAttributes(
                           typeof(CompilerGeneratedAttribute),
                           true
                       )
                       .Any();
    if (!mightBe) {
        return false;
    }


    bool maybe = info.DeclaringType
                     .GetFields(BindingFlags.NonPublic | BindingFlags.Instance)
                     .Where(f => f.Name.Contains(info.Name))
                     .Where(f => f.Name.Contains("BackingField"))
                     .Where(
                         f => f.GetCustomAttributes(
                             typeof(CompilerGeneratedAttribute),
                             true
                         ).Any()
                     )
                     .Any();

        return maybe;
    }

This is no wacky proof, rather fragile and probably not portable, say Mono.

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This should do:

public static bool IsAutoProperty(this PropertyInfo prop)
{
    return prop.DeclaringType.GetFields(BindingFlags.NonPublic | BindingFlags.Instance)
                             .Any(f => f.Name.Contains("<" + prop.Name + ">"));
}

The reason is that for auto-properties, the Name

substitution property FieldInfo

would look like this:

<PropertName>k__BackingField


Since symbols <

and are >

not displayed for normal fields, a field with this type of name points to an auto-property support field. As Jason says, he's still fragile.

Or do it a little faster,

public static bool IsAutoProperty(this PropertyInfo prop)
{
    if (!prop.CanWrite || !prop.CanRead)
        return false;

    return prop.DeclaringType.GetFields(BindingFlags.NonPublic | BindingFlags.Instance)
                             .Any(f => f.Name.Contains("<" + prop.Name + ">"));
}
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