DropCreateDatabaseAlways with overriden context.SaveChanges()

Question

I'm overriding DbContext.SaveChanges() in order to implement database auditing within my application.

My DbContext class looks like this:

public override int SaveChanges()
{
    throw new InvalidOperationException("User Id must be provided for auditing purposes.");
}

public int SaveChanges(bool suppressAudit)
{
    if (suppressAudit)
        return base.SaveChanges();
    else
        throw new InvalidOperationException("User Id must be provided for auditing purposes.");
}

public int SaveChanges(int userId)
{
    foreach(var entity in ChangeTracker.Entries().Where(p=>p.State == EntityState.Added || p.State == EntityState.Deleted || p.State == EntityState.Modified))
    {
        foreach(var auditEntry in GetAuditRecordsForChange(entity,userId))
        {
            Audit.Add(auditEntry);
        }
    }
    return base.SaveChanges();
}

and during "normal" operation of my application it seems to be working perfectly fine (at least, so far).

However, the problem comes when I want to recreate my database using an initializer, which looks like this:

public class ABS4Initializer : DropCreateDatabaseAlways<MyContext>
{        
        protected override void Seed(MyContext context)
        {
            var users = BuildUserData();            
            users.ForEach(u => context.Users.AddOrUpdate(u));
            context.SaveChanges(true);
        }
}

Despite me using the context.SaveChanges(true) call in the seed, something, somewhere, is calling context.SaveChanges() (and as such, the expected exception is thrown)

I suspect it surrounds the creation of the database / tables, but I can't find out where.

Sticking a break point on SaveChanges just shows that "External Code" is making the call: Call Stack

I'm assuming I've missed some override somewhere, or something even simpler/stupider.

Any clues?

(For reference, I'm trying to implement something similar to that shown as the top-voted answer on this question: how to create an audit trail with Entity framework 5 and MVC 4)

EDIT As requested in the comments, here is a FULL dbContext class that produces the same result:

public class DemoContext : DbContext
    {
        public DemoContext() : base("DemoContext")
        {

        }

        public DbSet<User> Users { get; set; }
        public DbSet<AuditLog> Audit { get; set; }

        public override int SaveChanges()
        {
            throw new InvalidOperationException("User Id must be provided for auditing purposes.");
        }

        public int SaveChanges(bool suppressAudit)
        {
            if (suppressAudit)
                return base.SaveChanges();
            else
                throw new InvalidOperationException("User Id must be provided for auditing purposes.");
        }

        public int SaveChanges(int userId)
        {
            foreach (var entity in ChangeTracker.Entries().Where(p => p.State == EntityState.Added || p.State == EntityState.Deleted || p.State == EntityState.Modified))
            {
                foreach (var auditEntry in GetAuditRecordsForChange(entity, userId))
                {
                    Audit.Add(auditEntry);
                }
            }
            return base.SaveChanges();
        }

        private List<AuditLog> GetAuditRecordsForChange(DbEntityEntry dbEntity, int userId)
        {
            return new List<AuditLog>();
        }
    }

App.config

<entityFramework>
    <contexts>
      <context type="DAL.DAL.DemoContext, DAL">
        <databaseInitializer type="DAL.DAL.ABS4Initializer, DAL"/>
      </context>
    </contexts>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="mssqllocaldb" />
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>

You are doing `if (suppressAudit) return base.SaveChanges();` Is that calling your breakpoint? — Amit, Jun 09 '15 at 10:18
@Amit no. It's calling down to the base class, which is fine and skips my override as expected. (sticking a breakpoint on that line as well confirms that) — Sk93, Jun 09 '15 at 10:28
@Amit not sure what more you need from the dbContext class? Apart from the public DbSet properties and the GetAuditRecordsForChange() method, there's nothing else there.. — Sk93, Jun 09 '15 at 10:42
And how you are setting initializer with respect to your DBContext? — Amit, Jun 09 '15 at 10:56

score 1 · Accepted Answer · answered Jun 12 '15 at 10:21

The DropCreateDatabaseAlways() class in Entity Framework has the following virtual method InitializeDatabase, if you download the EF source code you will find the implementation is something like this:

    public virtual void InitializeDatabase(TContext context)
    {
        Check.NotNull(context, "context");

        context.Database.Delete();
        context.Database.Create(DatabaseExistenceState.DoesNotExist);
        Seed(context);
        context.SaveChanges();
    }

You'll need to override with something like this:

public override void InitializeDatabase(ABSContext context)
        {
            if (context != null)
            {
                if (context.Database.Exists())
                {
                   context.Database.Delete();
                }

                context.Database.Create();
                Seed(context);
                context.SaveChanges(true);
            }
            else
                throw new ArgumentNullException();
        }

Thanks @Paul! That method wasn't showing up as an override for me for some reason, but it solved this problem! — Sk93, Jun 12 '15 at 10:25

DropCreateDatabaseAlways with overriden context.SaveChanges()

1 Answers1