Generic Command Pattern Implementation in Entity Framework Using System.Data.Entity.DbContext

Command.cs

/**
    Copyright (c) 2012 Brian Driscoll

    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
    in the Software without restriction, including without limitation the rights
    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in
    all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    THE SOFTWARE.
*/

public abstract class Command<TEntity> where TEntity : class
{
    public abstract void Execute(TEntity entity, DbContext workContext);
}

public class CommandProcessor<TEntity> where TEntity : class
{
    protected IEnumerable<ICommand<TEntity>> commands;
    protected DbContext workContext;

    public CommandProcessor(IEnumerable<Command<TEntity>> entityCommands, DbContext dbContext)
    {
        if (entityCommands == null)
        {
            throw new ArgumentNullException("commands");
        }
        if (dbContext == null)
        {
            throw new ArgumentNullException("workContext");
        }

        commands = entityCommands;
        workContext = dbContext;
    }

    public virtual void RunCommands(TEntity entity)
    {
        try
        {
            foreach (Command<TEntity> command in _commands)
            {
                command.Execute(entity, workContext);
            }

            workContext.SaveChanges();
        }
        catch (Exception ex)
        {
            throw new InvalidOperationException("Command execution resulted in an error. See inner exception for details.", ex);
        }
    }
}

public class Insert<TEntity> : Command<TEntity> where TEntity : class
{
    public void Execute(TEntity entity, DbContext workContext)
    {
        workContext.Entry<TEntity>(entity).State = System.Data.EntityState.Added;
    }
}

public class Update<TEntity> : Command<TEntity> where TEntity : class
{
    public void Execute(TEntity entity, DbContext workContext)
    {
        workContext.Entry<TEntity>(entity).State = System.Data.EntityState.Modified;
    }
}

public class Delete<TEntity> : Command<TEntity> where TEntity : class
{
    public void Execute(TEntity entity, DbContext workContext)
    {
        workContext.Entry<TEntity>(entity).State = System.Data.EntityState.Deleted;
    }
}