Compare equality of two objects based on dictionaries

Question

I have two objects with these definitions:

public static Dictionary<string, Container> cont1 = new Dictionary<string, Container>();
public static Dictionary<string, Container> cont2 = new Dictionary<string, Container>();

The schema of Container class is as following:

public class Container
{
    public string IDx { get; set; }
    public string IDy { get; set; }
    public string Name { get; set; }
    public Dictionary<string, Sub> Subs = new Dictionary<string, Sub>();
}

public class Sub
{
    public string Namex { get; set; }
    public string Namey { get; set; }
    public string Value { get; set; }
    public Dictionary<string, string> Paths { get; set; }
}

My question is: How can I deep check the equity of cont1 and cont2? I mean the equality of every member and value even deep down within Subs objects;

Is there any functionality in c# for such situations or I have to write a custom method for checking equality based on the structure of the objects myself;

Second Question: I can obviate the equality problem if I can create two different copies of Products; I mean say we have a base Container object with all the members and values and then create two separate copies of Container, namely cont1 and cont2 which changing a value in cont1 wont change the same value in cont2.

Note1 : this method for cloning is not working:

cont2 = new Dictionary<string, Container>(cont1);

Note2 : most of the proposed methods in other answers are based on a one level dictionary (using loops or LINQ for checking) and not such a case when we have properties and dictionary objects (which having their own properties) within the object.

Answer 1

A Dictionary is a Sequence, so in general what you're probably looking for is Enumerable<T>.SequenceEquals which allows passing in an IEquityComparer<T> .

Your sequence (Dictionary) is an IEnumerable<KeyValuePair<string,Container>> so you need an comparer which implements IEquityComparer<IEnumerable<KeyValuePair<string,Container>>> (Thats a lot of angle braces!).

var equal = cont1.SequenceEquals(cont2, new StringContainerPairEquityComparer());

Note that the order of elements dictionaries is not guaranteed, so to use the method properly you should probably use OrderBy before comparing sequences - however this adds to the inefficiency of this method.

---

For your second question, what you're trying to do is Clone the dictionary. In general your Container should implement ICloneable interface, which you can then use to create a copy

var cont2 = cont1.ToDictionary(k => k.Key, v => v.Value.Clone());

Answer 2

Yes, you have to write a custom method for checking equality based on the structure of the objects yourself. I would provide a custom IEqualityComparer<Container> and an IEqualityComparer<Sub> like here ( GetHashCode implementation based on this ):

public class ContainerCheck : IEqualityComparer<Container>
{
    private SubCheck subChecker = new SubCheck();
    public bool Equals(Container x, Container y)
    {
        if (ReferenceEquals(x, y))
            return true;
        if (x == null || y == null)
            return false;
        if (x.IDx != y.IDx || x.IDy != y.IDy || x.Name != y.Name)
            return false;
        // check dictionary
        if (ReferenceEquals(x.Subs, y.Subs))
            return true;
        if (x.Subs == null || y.Subs == null || x.Subs.Count != y.Subs.Count)
            return false;
        foreach (var kv in x.Subs)
            if (!y.Subs.ContainsKey(kv.Key) || subChecker.Equals(y.Subs[kv.Key], kv.Value))
                return false;
        return true;

    }

    public int GetHashCode(Container obj)
    {
        unchecked // Overflow is fine, just wrap
        {
            int hash = 17;
            // Suitable nullity checks etc, of course :)
            hash = hash * 23 + obj.IDx.GetHashCode();
            hash = hash * 23 + obj.IDy.GetHashCode();
            hash = hash * 23 + obj.Name.GetHashCode();
            foreach (var kv in obj.Subs)
            {
                hash = hash * 23 + kv.Key.GetHashCode();
                hash = hash * 23 + subChecker.GetHashCode(kv.Value);
            }

            return hash;
        }
    }
}

public class SubCheck : IEqualityComparer<Sub>
{
    public bool Equals(Sub x, Sub y)
    {
        if (ReferenceEquals(x, y))
            return true;
        if (x == null || y == null)
            return false;
        if (x.Namex != y.Namex || x.Namey != y.Namey || x.Value != y.Value)
            return false;
        // check dictionary
        if (ReferenceEquals(x.Paths, y.Paths))
            return true;
        if (x.Paths == null || y.Paths == null || x.Paths.Count != y.Paths.Count)
            return false;
        foreach(var kv in x.Paths)
            if (!y.Paths.ContainsKey(kv.Key) || y.Paths[kv.Key] != kv.Value)
                return false;
        return true;
    }

    public int GetHashCode(Sub obj)
    {
        unchecked // Overflow is fine, just wrap
        {
            int hash = 17;
            // Suitable nullity checks etc, of course :)
            hash = hash * 23 + obj.Namex.GetHashCode();
            hash = hash * 23 + obj.Namey.GetHashCode();
            hash = hash * 23 + obj.Value.GetHashCode();
            foreach (var kv in obj.Paths)
            {
                hash = hash * 23 + kv.Key.GetHashCode();
                hash = hash*23 + kv.Value.GetHashCode();
            }

            return hash;
        }
    }
} 

This should deep check all properties and the dictionaries. Then you could use following loop to compare both dictionaries with each other:

bool equal = true;
var allKeys = cont1.Keys.Concat(cont2.Keys).ToList();
var containerChecker = new ContainerCheck();

foreach (string key in allKeys)
{
    Container c1;
    Container c2;
    if (!cont1.TryGetValue(key, out c1) || !cont2.TryGetValue(key, out c2))
    {
        equal = false;
    }
    else
    {
        // deep check both containers
        if (!containerChecker.Equals(c1, c2))
            equal = false;
    }
    if(!equal)
        break;  // or collect differences
}