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

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

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()?

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

CREATE DATABASE permission denied in database ‘master’ (EF code-first)

I had the same problem. This what worked for me: Go to SQL Server Management Studio and run it as Administrator. Choose Security -> Then Logins Choose the usernames or whatever users that will access your database under the Logins and Double Click it. Give them a Server Roles that will give them credentials to … Read more

Oracle.ManagedDataAccess.EntityFramework – ORA-01918: user ‘dbo’ does not exist

I had the same problem and it was resolved by Thiago Lunardi’s response. Thank you. I didn’t have enough reputation to vote up your response. To mention here, I succeeded after setting my schema name in UPPERCASE. Put this in your Context file under your new dbContext class, like this: public partial class MyAppContext : … Read more

ALTER TABLE DROP COLUMN failed because one or more objects access this column

You must remove the constraints from the column before removing the column. The name you are referencing is a default constraint. e.g. alter table CompanyTransactions drop constraint [df__CompanyTr__Creat__0cdae408]; alter table CompanyTransactions drop column [Created];

How can I disable code first migrations

set the Database.SetInitializer to null. public class DatabaseContext: DbContext { //the base accepts the name of the connection string provided in the web.config as a parameter public DatabaseContext() : base(“DatabaseContext”) { //disable initializer Database.SetInitializer<DatabaseContext>(null); }

Entity Framework CTP 4 – Code First Custom Database Initializer

I ran into the same problem. I didn’t really solve it, but I managed to get a little nasty workaround running, so i can deploy my solution to AppHarbor 😉 Its a IDatabaseInitializer implementation, that doesn’t delete the db, but just nukes all the constraints and tables, and then uses the ObjectContext.CreateDatabaseScript() method to generate … Read more

Using MySql with Entity Framework 4 and the Code-First Development CTP

Right, finally got it working with a few points of interest. Cannot create a DB, must exist already You have to create a connection string for each DB contest using the DBContext name (in the above example a connectionstring must exist with the name “NerdDinners”), not just a default one (else it will use SQL) … Read more

Understanding ForeignKey attribute in entity framework code first

The required side of the 1..0 relationship MemberDataSet should not have a FK to DeferredData. Instead, DeferredData‘s PK should also be a FK to MemberDataSet (known as shared primary key) public class MemberDataSet { [Key] [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)] public int Id { get; set; } public virtual DeferredData DeferredData { get; set; } } public class DeferredData … Read more