WCF Data Services and Entity Framework Code First?

2
votes

Does WCF Data Services support working with Entity Framework Code First (4.1)? It seems like it's having a hard time understanding what to do with DbSet or DbContext. I suppose this shouldn't be too surprising since EFCF was released after Data Services.

internal class Context:DbContext {
    public Context(String nameOrConnectionString) : base(nameOrConnectionString) { }

    public DbSet<AlertQueue> Alerts { get; set; }
}

public class EntitySet:Abstract.EntitySet {
    public EntitySet(String nameOrConnectionString) {
        var context = new Context(nameOrConnectionString);

        this.AlertQueueRepository = new Concrete.AlertQueueRepository(new Repository<AlertQueue>(context, context.Alerts));
    }
}

public class AlertQueueRepository:EntityRepository<AlertQueue> {
    public AlertQueueRepository(IEntityRepository<AlertQueue> entityRepository):base(entityRepository) { }

    public IQueryable<AlertQueue> Pending {
        get {
            return (from alert in this.All
                    where alert.ReviewMoment == null
                    select alert);
        }
    }
}

EntityRepository and IEntityRepository provide generic methods for All and other CRUD functions. This is the WCF Data Service that isn't working:

public class WcfDataService1:DataService<Domain.Concrete.AlertQueueRepository> {
    public static void InitializeService(DataServiceConfiguration config) {
        config.SetEntitySetAccessRule("All", EntitySetRights.AllRead);
        config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;
    }
}
2
entity-framework-4.1wcf-data-services
Do you like to use WCF Data service with EFv4.1 or with custom repository? That is pretty big difference. – Ladislav Mrnka
The only reason I have the EntitySet was so that I could provide a single object to controllers in MVC and they'd be able to query whichever entity sets they needed. – Yuck
But why not to pass DbContext directly? – Ladislav Mrnka
As an aside, it would be awesome if WCF Data Services actually provided an error message instead of its useless "The server encountered an error processing the request. See server logs for more details." – Yuck
They provide error but you have to tell them to do that: stackoverflow.com/questions/2312894/… – Ladislav Mrnka

2 Answers

2
votes

I just made this very simple test:

WCF Service:

public class WcfDataService : DataService<Context>
{
    public static void InitializeService(DataServiceConfiguration config)
    {
        config.SetEntitySetAccessRule("*", EntitySetRights.All);
        config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2;
    }
}

Context:

public class Context : DbContext
{
    public DbSet<User> Users { get; set; }

    public Context()
    {
        this.Configuration.ProxyCreationEnabled = false;
    }
}

[DataServiceKey("Id")]
public class User
{
    public int Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

And it works but I'm afraid that it is read only. Here is a workaround to allow data modifications.

2
votes

You need to install Microsoft WCF Data Services 2011 CTP2.

Here is a good step by step article from the ADO.NET Team Blog: Using WCF Data Services with Entity Framework 4.1 and Code First

You will need to change the reference for “System.Data.Services” and “System.Data.Services.Client” to “Microsoft.Data.Services” and “Microsoft.Data.Services.Client” after installing the CTP and then you will have a new V3 protocol version (DataServiceProtocolVersion.V3)

Add a constructor like below to pass in a connection string or database name

public class HospitalContext : DbContext
{
    public HospitalContext(string dbname) : base(dbname)
    {
    }

    public DbSet<Patient> Patients { get; set; }
    public DbSet<LabResult> LabResults { get; set; }
}