Switch Azure DB to EF6 code first

Question

Hello.

When translating our project to EF6 code first , we are faced with the
following problem :

It is impossible to change the database schema .

Extend the methods to switch context to another scheme of the box we found
How to advise developers on the forums , change the database schema can only be
at the time of initialization and construction of the metadata for database
objects .

This construction is performed with a method call:
protected override void OnModelCreating (DbModelBuilder
modelBuilder)

However, this method is called only once - when the first call to the context.
All further context calls do not result in a call to this method .

How to advise developers on the forums , it is due to the creation of metadata
cache , disable the cache is not possible .

That piece of code , the switching circuitry to initialize :

public partial class effiedbEntities : DbContext

{

        private string schemaName {
get; set; }

        public effiedbEntities(string schemaName) : base("name=effiedbEntitiesDev")

        {

           
// DbModelBuilder builder = new
DbModelBuilder();

           
// Указываем необходимы классы модели

           
// builder.Entity<ChannelSales>();

           
// Запускаем вручную процесс создания модели

           
// DbModel mod = builder.Build(new
DbProviderInfo("System.Data.SqlClient", "2012"));

           
// DbCompiledModel res_mod = mod.Compile();

     
      this.schemaName = schemaName;

           
Database.SetInitializer(new CreateDatabaseIfNotExists<effiedbEntities>());

           

     // Database.Initialize(true);

           
// OnModelCreating(new DbModelBuilder());

        }

        public virtual DbSet<ChannelSales> ChannelSales { get; set; }

protected override void OnModelCreating(DbModelBuilder modelBuilder)

{

       // Define schemaName for entities
===================================================

      
modelBuilder.Entity<ChannelSales>().ToTable("ChannelSales", schemaName);

       // Define schemaName for entities
===================================================

modelBuilder.Entity<ChannelSales>()

               
.HasMany(e => e.QuestItems)

               
.WithOptional(e => e.ChannelSales)

               
.HasForeignKey(e => e.ChannelSaleID);

      
modelBuilder.Entity<ChannelSales>()

               
.HasMany(e => e.TT)

               
.WithRequired(e => e.ChannelSales)

               
.HasForeignKey(e => e.ChannelSaleID);

}

}

I need help

How to switch to EF6 code first

Thanks

Answer 1

I don't understand your question.  Can you describe again what you are trying to do and the problem you are having?

David

---

David http://blogs.msdn.com/b/dbrowne/

Answer 2

The problem is the following
We use several database schemas Azure SQL, for example, u1 and u2
At the time of receiving the first request for a service that uses the EF code first, a method that defines and switches us to a necessary schema runs
When you connect for the first time - everything works
If we get a second request, addressed to the other schemes, such as u2, then switch to a scheme u2 does not happen
Using Debugging tools, we see that there is an attempt to switch to a schema u1
We think that this is because of cache, which remains after the first connection
Now we use the 6.1.3 version of the EF
As a way of solving the problem may be option to disable the cache, as in the previous versions EF or something else

Answer 3

>We think that this is because of cache

Likely yes.

I think you'll need to drop down and handle the DbCompiledModel caching manually for this, creating and caching one per schema.  So instead of overriding OnModelCreating, you do something like:

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication19
{
    public class MyEntity
    {
        public int Id { get; set; }
        public string Name { get; set; }
    }

    class MyDb : DbContext
    {
        static ConcurrentDictionary<string, DbCompiledModel> modelCache = new ConcurrentDictionary<string, DbCompiledModel>();

        static DbCompiledModel GetModelForSchema(string connectionString, string schema)
        {
            schema = schema.ToUpper();

            if (modelCache.ContainsKey(schema))
            {
                return modelCache[schema];
            }

            var mb = new DbModelBuilder();

            mb.HasDefaultSchema(schema);
            mb.Entity<MyEntity>().ToTable("MY_ENTITY");

            var model = mb.Build(new System.Data.SqlClient.SqlConnection(connectionString));
            var compiledModel = model.Compile();
            modelCache.AddOrUpdate(schema, compiledModel, (key, oldValue) => oldValue);

            return modelCache[schema];
      

        }
        public MyDb( string connectionString, string schema) : base(connectionString,GetModelForSchema(connectionString,schema))
        {

        }
        public DbSet<MyEntity> MyEntities { get; set; }

        
    }
    class Program
    {
        static void Main(string[] args)
        {
            
            using (var db = new MyDb("server=.;Database=MyDatabase;Integrated Security=true", "schema1"))
            {
                if (db.Database.Exists())
                      db.Database.Delete();

                db.Database.Initialize(true);
            }

            using (var db = new MyDb("server=.;Database=MyDatabase;Integrated Security=true", "schema2"))
            {
                db.Database.Initialize(true);
            }
        }
    }
}

David

---

David http://blogs.msdn.com/b/dbrowne/

Answer 4

Many thanks, David

It works!