Is there an easy way to make EntityFramework use SQL default values?

Question

For example, most of my entities have DateCreated and DateModified fields. The defaults to these are set to GetUtcDate() in SQL Server.

If I try and create an entity and don't set these values, I get an exception saying it can't run the SQL insert because the date value is out of range. Makes sense because C# default dates are 1/1/0001 while SQL Server's minimum date is 1/1/1753.

So is there a way I can tell EF to either use the SQL Server default values, or to NOT try and insert columns which have not been set?

Ladislav Mrnka · Accepted Answer · 2011-05-11 14:10:29Z

12

You must set StoreGeneratedPattern for those properties to Identity for DateCreated and Computed for DataModified. It is available in designer. Once you do that you cannot modify those values in your application - only database can set those properties. I wrote about this some article because this feature had bug before VS2010 SP1 but there are reports that it still doesn't work sometimes.

answered May 11, 2011 at 14:10

Ladislav Mrnka

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9 Comments

Rachel Over a year ago

Thanks, I did give that a try before posting this but it wasn't working. I'm using VS 2010 Ultimate, SP1 and EF4

Ladislav Mrnka Over a year ago

In such case check that correct store generated pattern is set both in CSDL and SSDL part of EDMX file (you must open it as XML) because this is valid way to do that.

Rachel Over a year ago

@Ladislav I am giving this another try, however I am getting errors about a Non-Nullable column getting mapped to a nullable entity property. Do you know what it's talking about?

Ladislav Mrnka Over a year ago

Is any of these properties nullable?

Ladislav Mrnka Over a year ago

@Rachel: In such case Computed will not work as well because neither computed or identity properties are included in insert / update SQL command. You will have to handle default value in the application if you need that.

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James McCormack · Accepted Answer · 2011-05-11 14:30:00Z

One solution is to override your generated entitycontext class by using partial. This will intercept inserts/updates on all the entity classes in your EF context:

public partial class MyEntities : ObjectContext
{
    public override int SaveChanges(SaveOptions options)
    {
        this.DetectChanges();

        foreach (var insert in this.ObjectStateManager.GetObjectStateEntries(System.Data.EntityState.Added))
        {
            if (insert.Entity.HasProperty("DateCreated"))
                insert.Entity.GetType().GetProperty("DateCreated").SetValue(insert.Entity, DateTime.UtcNow, null);
            if (insert.Entity.HasProperty("LastModified"))
                insert.Entity.GetType().GetProperty("LastModified").SetValue(insert.Entity, DateTime.UtcNow, null);
        }

        foreach (var update in this.ObjectStateManager.GetObjectStateEntries(System.Data.EntityState.Modified))
        {
            if (update.Entity.HasProperty("LastModified"))
                update.Entity.GetType().GetProperty("LastModified").SetValue(update.Entity, DateTime.UtcNow, null);
        }

        return base.SaveChanges(options);
    }
}

Or do something similar, looking for inserts/updates on your datestamp fields and removing them from the ObjectStateEntries collection?

JTorrecilla · Accepted Answer · 2011-05-11 13:54:56Z

0

Have you tryed to set the DefaultValue of the Property in the Entity?

answered May 11, 2011 at 13:54

JTorrecilla

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1 Comment

Rachel Over a year ago

I'm really hoping to avoid having to go through all my entities and adjusting the default value of every property. Also, it means if I change the default in SQL server I need to change the default in EF and recompile

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