Deep cloning object in C#/.NET

I was asked recently to write a generic method for deep cloning of a complex object. The object contains references to other objects, collections, which contain references to many other objects and collections. The method was supposed to work on both platforms: .NET 3.5 (or higher) and Silverlight.

While googling I found a good post listing different approaches for cloning
C# Object Clone Wars

Last technique described in that blog points to Copyable Framework - generic framework for copying/cloning any objects using method extensions

The framework, written by Håvard Stranden addresses most of my requirements, except one: it does not work on Silverlight.

I came up with a simple method that serializes the original object and deserializes it to a cloned copy of it. It can be used as an extension or by implementing IClonable interface:

public static class ObjectExtensions
{
  public static T Clone<T>(this object original)
  {
    T cloned;
    using (MemoryStream stream = new MemoryStream())
    {
      DataContractSerializer serializer = new DataContractSerializer(typeof(T));
      serializer.WriteObject(stream, original);
      stream.Position = 0;
      cloned = (T)serializer.ReadObject(stream);
    }
    return cloned;
  }
}

* This source code was highlighted with Source Code Highlighter.

WCF Serialization Tips

Here are a few tips on how to improve WCF performance and traffic by simple putting the right attributes on your serializable classes:


1. "Avoid inferred data contracts (POCO). Always be explicit and apply the DataContract attribute" (C) Juval Löwy
2. "Use the DataMember attribute only on properties or read-only public members" (C) Juval Löwy
3. Mark [DataMember] only properties, that DO have to be serialized. Avoid marking calculated properties as DataMember
2. Consider using (IsReference = true) on classes to avoid data duplication and circular references.
3. Use short (one or two letters) Name on classes and properties to significantly reduce traffic. (C) Eyal Vardi
4. Specify short Value for EnumMember
5. Use parametrized DataContract property for generic classes
6. Use (EmitDefaultValue=false) on properties to reduce traffic

Sample:

[DataContract(Name="CT")]
  public enum CustomerTypes
  {
    [EnumMember(Value = "I")]
    Internal,
    [EnumMember(Value = "E")]
    External,
    [EnumMember(Value = "U")]
    Unknown
  }

  [DataContract(IsReference = true, Name = "B{0}")]
  public class BusinessBase<T>
  {
    T Id { get; set; }
  }

  [DataContract(IsReference = true, Name = "C")]
  public class Customer : BusinessBase<int>
  {
    [DataMember(Name="C", EmitDefaultValue=false)]
    public CustomerTypes CustomerType { get; set; }

    [DataMember(Name = "N", EmitDefaultValue = false)]
    public string Name { get; set; }

    [DataMember(Name = "P", EmitDefaultValue = false)]
    public Customer ParentCustomer { get; set; }

    public bool IsGoodCustomer
    {
      get
      {
        return this.CustomerType == CustomerTypes.Internal || this.CustomerType == CustomerTypes.External;
      }
    }

  }

* This source code was highlighted with Source Code Highlighter.

System.Data.DataRow indexer complexity

Have you ever wonder what is the time complexity of accessing DataRow by column name? Unfortunately, this information is not specified on MSDN.

So the obvious answer would be O(n). We might think that there is iteration on data columns and in worst case it would iterate on all of them.

The actual answer can be discovered by looking on System.Data.dll using Reflector. We'll see there, that there is an access to Hashtable of column names by name, which obviosly take O(1).

So the overall complexity of the following would be O(1).

object data = row["CUSTOMER"];

How to retrieve new row data from INSERT using Oracle DataAccess

Answering a question on StackOverflow:

"I am using Oracle database server with Oracle DataAccess client. What I need to do is INSERT a new row of data, then retrieve the auto-generated ID field of the newly-created row for another INSERT command, immediately following. What is the best way to do this?"

Answer:
1. Modify the INSERT query by adding RETURNING keyword

"INSERT INTO table_name (column_name1, column_name2) VALUES ('val1', 'val2')
RETURNING module_id INTO :column_id"

* This source code was highlighted with Source Code Highlighter.

2. Add a bind variable to your OracleCommand named "column_id"
3. Take its value after the command is executed

V2: WCF CollectionDataContract and DataMember attributes

Following Jeff's comment on the first version of this post, here are some explanations and a full class.

Q1. Why did I write "implement IEnumerable" twice?
A1. My original intention was to derive my class from ICollection<T>. Thus I had to implement IEnumerable and IEnumerable<T>.

Q2. Why do I bother to implement IEnumerable at all if the class is not "decorated" as IEnumerable?
A2. ICollection<T> "derives" from IEnumerable<T> and IEnumerable, so we have to implement both of them when writing a class that implements ICollection<T>

Here is a complete class:

 [DataContract]
  public class EntityCollectionWorkaround<EntityType> : ICollection<EntityType>
  {
    #region Constructor
    public EntityCollectionWorkaround()
    {
      Entities = new List<EntityType>();
    }
    #endregion

    [DataMember]
    public int AdditionalProperty { get; set; }

    [DataMember]
    public List<EntityType> Entities { get; set; }

    #region ICollection<T> Members

    public void Add(EntityType item)
    {
      Entities.Add(item);
    }

    public void Clear()
    {
      this.Entities.Clear();
    }

    public bool Contains(EntityType item)
    {
      return Entities.Contains(item);
    }

    public void CopyTo(EntityType[] array, int arrayIndex)
    {
      this.Entities.CopyTo(array, arrayIndex);
    }

    public int Count
    {
      get
      {
        return this.Entities.Count;
      }
    }

    public bool IsReadOnly
    {
      get
      {
        return false;
      }
    }

    public bool Remove(EntityType item)
    {
      return this.Entities.Remove(item);
    }

    public EntityType this[int index]
    {
      get
      {
        return this.Entities[index];
      }
      set
      {
        this.Entities[index] = value;
      }
    }
    #endregion

    #region IEnumerable<T> Members

    public IEnumerator<EntityType> GetEnumerator()
    {
      return this.Entities.GetEnumerator();
    }

    #endregion

    #region IEnumerable Members

    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
    {
      return this.Entities.GetEnumerator();
    }

    #endregion
  }

* This source code was highlighted with Source Code Highlighter.