Override SaveChangesAsync

Question

Does anyone know how to override SaveChangesAsync? I know a similar question was posted but there was no answer. I have the following code below:

public override async Task<int> SaveChangesAsync()
{
    PerformFurtherValidations();
    return await base.SaveChangesAsync();
}

During Build I get the following error message:

Error SaveChangesAsync(): return type must be System.Threading.Tasks.Task<int> to match overridden member System.Data.Entity.DbContext.SaveChangesAsync()

Answer 1

public override async Task<int> SaveChangesAsync(CancellationToken cancellationToken = default(CancellationToken))
{
    return (await base.SaveChangesAsync(true, cancellationToken));
}

Answer 2

Old question, but I had a similar problem and resolved it with the following code:

    public override async Task<int> SaveChangesAsync()
    {
        foreach (var history in this.ChangeTracker.Entries()
            .Where(e => e.Entity is IModificationHistory && (e.State == EntityState.Added ||
                e.State == EntityState.Modified))
            .Select(e => e.Entity as IModificationHistory)
            )
        {
            history.DateModified = DateTime.Now;
            if (history.DateCreated <= DateTime.MinValue)
            {
                history.DateCreated = DateTime.Now;
            }
        }
        int result = await base.SaveChangesAsync();
        foreach (var history in this.ChangeTracker.Entries()
                                        .Where(e => e.Entity is IModificationHistory)
                                        .Select(e => e.Entity as IModificationHistory))
        {
            history.IsDirty = false;
        }
        return  result;
    }

The custom SaveChangesAsync() allows me to tweak the dirty flag, date created and date modified.

Answer 3

It's better to return the task to the caller, you don't need to call an async method inside your version of SaveChanges, just omit "await" and "async" keywords:

public override Task<int> SaveChangesAsync(CancellationToken cancellationToken = default)
{
    PerformFurtherValidations();
    return base.SaveChangesAsync();
}

Answer 4

I faced the same issue and the root cause was that the EntityFramework reference to the project was from

\packages\EntityFramework.6.3.0\lib.net40

folder instead of

\packages\EntityFramework.6.3.0\lib.net45