RIA Services + Entity Framework 4 + POCO's : 'The Timestamp field is required' error?

Question

I've the following table definition in MSSQL:

CREATE TABLE [User] ( 
    [Id] bigint identity(1,1)  NOT NULL,
    [Email] nvarchar(256),
    [PasswordHash] nvarchar(128) NOT NULL,
    [PasswordFormat] int DEFAULT ((0)) NOT NULL,
    [PasswordSalt] nvarchar(10) NOT NULL,
    [Timestamp] timestamp
)
;

The EDMX property for Timestamp looks like this: (Note only the red property has been manually changed by me)

I used the t4 template to automatically generate POCO entities. The User entity looks like this:

public partial class User : IEntity
{
    public virtual long Id
    {
        get;
        set;
    }
    ...

    [TimestampAttribute]
    [ConcurrencyCheck]
    [SuppressMessage("Microsoft.Performance", "CA1819:PropertiesShouldNotReturnArrays", Justification = "Autogenerated by T4.")]
    public virtual byte[] Timestamp
    {
        get;
        set;
    }

    ...
}

When doing a 'SaveChanges' operation on the ObjectContext, I get a validation error for the User entity which is called : The Timestamp field is required

Answer 1

Solution:

I've changed the T4 generated User class to: (removed the 'ConcurrencyCheck' attribute)

public partial class User : IEntity
{
    public virtual long Id
    {
        get;
        set;
    }
    ...

    [TimestampAttribute]
    [SuppressMessage("Microsoft.Performance", "CA1819:PropertiesShouldNotReturnArrays", Justification = "Autogenerated by T4.")]
    public virtual byte[] Timestamp
    {
        get;
        set;
    }

    ...
}

And I've added a generic metadata class which is used by all Entities which excludes the Timestamp property :

/// <summary>
/// A MetaData which defines some default metadata for an Entity
/// </summary>
public class EntityMetaData
{
    /// <summary>
    /// Initializes a new instance of the <see cref="EntityMetaData"/> class.
    /// </summary>
    protected EntityMetaData()
    {
    }

    /// <summary>
    /// Gets or sets the timestamp.
    /// Note : this field is excluded on the client.
    /// </summary>
    /// <value>The timestamp.</value>
    [Exclude]
    public byte[] Timestamp { get; set; }
}

This solves the issue.