code-first

EF4 Code First: how to add a relationship without adding a navigation property

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I believe you always need navigation property on at least one side when using code-first. Then you will be able to map it: public class User { public string UserId { get; set; } public string PasswordHash { get; set; } public bool IsDisabled { get; set; } public DateTime AccessExpiryDate { get; set; } … Read more

Self-referencing many-to-many recursive relationship code first Entity Framework

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By convention, Code First will take uni-directional associations as one to many. Therefore you need to use fluent API to let Code First know that you want to have a many to many self referencing association: protected override void OnModelCreating(ModelBuilder modelBuilder) { modelBuilder.Entity<Member>().HasMany(m => m.Friends).WithMany().Map(m => { m.MapLeftKey(“MemberId”); m.MapRightKey(“FriendId”); m.ToTable(“MembersFriends”); } ); }

SQL Server Express connection string for Entity Framework Code First

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The problem with your connection string here is: <add name=”TrempimModel” connectionString=”data source=.\SQLEXPRESS;Integrated Security=SSPI; AttachDBFilename=|DataDirectory|aspnetdb.sdf; User Instance=true” providerName=”System.Data.SqlClient” /> You’re basically defining what “server” you’re connecting to – but you’re not saying what database inside the file to connect to. Also – the file extension for SQL Server Express database files is .mdf (not .sdf – … Read more

Entity Framework – Is there a way to automatically eager-load child entities without Include()?

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No you cannot do that in mapping. Typical workaround is simple extension method: public static IQueryable<Car> BuildCar(this IQueryable<Car> query) { return query.Include(x => x.Wheels) .Include(x => x.Doors) .Include(x => x.Engine) .Include(x => x.Bumper) .Include(x => x.Windows); } Now every time you want to query Car with all relations you will just do: var query = … Read more

Validation failed for one or more entities while saving changes to SQL Server Database using Entity Framework

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You can extract all the information from the DbEntityValidationException with the following code (you need to add the namespaces: System.Data.Entity.Validation and System.Diagnostics to your using list): catch (DbEntityValidationException dbEx) { foreach (var validationErrors in dbEx.EntityValidationErrors) { foreach (var validationError in validationErrors.ValidationErrors) { Trace.TraceInformation(“Property: {0} Error: {1}”, validationError.PropertyName, validationError.ErrorMessage); } } }

Why use ICollection and not IEnumerable or List on many-many/one-many relationships?

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Usually what you choose will depend on which methods you need access to. In general – IEnumerable<> (MSDN: http://msdn.microsoft.com/en-us/library/system.collections.ienumerable.aspx) for a list of objects that only needs to be iterated through, ICollection<> (MSDN: http://msdn.microsoft.com/en-us/library/92t2ye13.aspx) for a list of objects that needs to be iterated through and modified, List<> for a list of objects that needs … Read more

Does Entity Framework Code First support stored procedures?

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EDIT: My original answer for EF4.1 (below) is now out of date. Please see the answer below from Diego Vega (who works on the EF team at Microsoft)! @gsharp and Shawn Mclean: Where are you getting this information? Don’t you still have access to the underlying ObjectContext? IEnumerable<Customer> customers = ((IObjectContextAdapter)this) .ObjectContext.ExecuteStoreQuery<Customer>(“select * from customers”); … Read more

Entity Framework DateTime and UTC

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Here is one approach you might consider: First, define this following attribute: [AttributeUsage(AttributeTargets.Property)] public class DateTimeKindAttribute : Attribute { private readonly DateTimeKind _kind; public DateTimeKindAttribute(DateTimeKind kind) { _kind = kind; } public DateTimeKind Kind { get { return _kind; } } public static void Apply(object entity) { if (entity == null) return; var properties = … Read more