Question

I’m using the entity framework and I have some properties which are common to all entities:

CreatedByUserName
CreatedDateTime
LastModifiedByUserName
LastModifiedDatetime

So currently I’m saving a new property and I’m having to go like this:

_db.ProjectApprovals.Add(projectApproval);
                    projectApproval.CreatedByUserName = "Dev";
                    projectApproval.CreatedDateTime = DateTime.Now;
                    _db.SaveChanges();

As you can imagine having to do:

projectApproval.CreatedByUserName = "Dev";
                        projectApproval.CreatedDateTime = DateTime.Now;

for all entities every save is a pain. I was thinking of wrapping the save and then I could do it in there. The problem is how would I know which entities in the context had been added or modified.

Answer 1

First of all you must define shared interface for all your entities implementing these properties:

public interface IEntity
{
    string CreatedByUserName { get; set; }
    DateTime CreatedDateTime { get; set; }
    ...
}

Implement this interface in your entities and override SaveChanges method in your derived ObjectContext.

public override int SaveChanges(SaveOptions saveOptions)
{
    var entries = this.ObjectStateManager
                      .GetObjectStateEntries(EntityState.Added | EntityState.Modified)
                      .Where(x => !x.IsRelationship && x.Entity is IEntity);

    foreach (var entry in entiries)
    {
       var entity = entry.Entity as IEntity;

       if (entry.State == EntityState.Added)
       {
          ...
       } 
       else
       { 
          ...
       }
    }


    return SaveChagnes(saveOptions);
}