How do I find an object(s) by its hashcode?

Question

Is there an easy way to dig in to an object and find a property or field by its hashcode? This could be a nested property or a value in a collection. The reason I ask is that I occasionally get WPF warnings that look like:

System.Windows.ResourceDictionary Warning: 9 : Resource not found;
  ResourceKey='#FF000000'; ResourceKey.HashCode='51639504';
  ResourceKey.Type='System.Windows.Media.SolidColorBrush' 

The warning doesn't always appear and I'm having the hardest time tracking it down. I figure if I knew which object had that hashcode, I could get closer to fixing this. For instance, if I had this object:

var first = new { a = 1, b = 2, d = new { aa = 11, bb = 22 } };

and called this on it:

string str = FindHashCode(first, 22);

the result would be:

"Anon > d > bb.hashcode = 22"

or something similar. (I'm ignoring hashcode collisions for now)

---

Edit: Here's what I'll use based on @Alberto's answer. It searches both fields and properties whether public or non-public. It includes support for IEnumerables (Lists, Arrays, etc.) and more specifically IDictionaries. It also handles hashcode collisions. If two objects have the same hashcode, the StringBuilder will have a separate line for each object.

using System.Reflection;

static string FindHashCode(object o, int hashCode)
{
    StringBuilder strb = new StringBuilder();
    FindHashCode(o, hashCode, o.GetType().Name, strb);
    return strb.ToString().Trim();
}

static void FindHashCode(object o, int hashCode, string path, StringBuilder strb)
{
    if (o.GetHashCode() == hashCode)
    {
        strb.AppendLine(path + ".hashcode = " + hashCode);
    }

    foreach (var field in GetFieldInfo(o))
    {
        if (field.Item1 == null || object.ReferenceEquals(o, field.Item1))
            continue;

        Type type = field.Item1.GetType();
        if (type.IsPrimitive)
        {
            if(field.Item1.GetHashCode() == hashCode)
                strb.AppendLine(path + " > " + field.Item2 + ".hashcode = " + hashCode);
        }
        else
        {
            FindHashCode(field.Item1, hashCode, path + " > " + field.Item2, strb);
        }
    }
}

static IEnumerable<Tuple<object, string>> GetFieldInfo(object arg)
{
    var ienum = arg as System.Collections.IEnumerable;
    var idict = arg as System.Collections.IDictionary;

    if (ienum == null && idict == null)
    {
        BindingFlags bf = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance;
        Type type = arg.GetType();

        var list = type.GetFields(bf).Select(s => new Tuple<object, string>(s.GetValue(arg), s.Name)).Concat(
            type.GetProperties(bf).Select(s => new Tuple<object, string>(s.GetValue(arg, null), s.Name)));

        foreach (var item in list)
        {
            yield return item;
        }
    }
    else if (idict != null)
    {
        foreach (System.Collections.DictionaryEntry item in idict)
        {
            yield return new Tuple<object, string>(item.Key, string.Format("Dict[{0}].Key", item.Key));
            yield return new Tuple<object, string>(item.Value, string.Format("Dict[{0}].Value", item.Key));
        }
    }

    //note that dictionaries implement IEnumerable
    else if (ienum != null && !(ienum is string)) 
    {
        int count = 0;
        foreach (var item in ienum)
        {
            yield return new Tuple<object, string>(item, string.Format("this[{0}]", count));
            count++;
        }
    }
}

Answer 1

Here an implementation that search recursively in an object graph for a property with a specific hashcode:

static string FindHashCode(object o, int hashCode)
{
    return FindHashCodeImpl(o,hashCode, o.GetType().Name);
}

static string FindHashCodeImpl(object o, int hashCode, string partialPath)
{
    var type = o.GetType();
    var properties = type.GetProperties();
    foreach (var property in properties)
    {
        var propValue = property.GetValue(o);
        if (propValue.GetHashCode() == hashCode)
        {
            return partialPath + " > " + property.Name + ".hashcode = " + hashCode;
        }

        var path = FindHashCodeImpl(propValue, hashCode, partialPath + " > " + property.Name);
        if (path != null)
        {
            return path;
        }
    }
    return null;
}

Use it like:

var o = new { a = 1, b = 2, d = new { aa = 11, bb = 22 } };

var s = FindHashCode(o, 22); //Output "<>f__AnonymousType1`3 > d > bb.hashcode = 22"

You should extend it to search inside fields as well.

P.S I didn't test it for every scenario, but it should work...