EF 6-在运行时在架构之间切换

Question

I'm developing an ASP.NET 4.6.2 Web App with EF 6. The backend is a PostgreSQL database in several schemas : the tables and views are exactly the same in every schema. Depending on what the users do, I must connect specifically to one schema or another.

That works fine by overriding the OnModelCreating method but only once.

Should the user want to change his environment, I can instanciate the context with the right parameter but it doesn't call the OnModelCreating method. The context is kept somewhere and connects to the previous schema.

-> How can I invalidate the context or force the switch to the other schema ?

Here's my code :

  public partial class MyDB : DbContext
{
    public Instances Instance { get; set; }
    public string Schema
    {
        get
        {
            switch(Instance)
            {
                case Instances.I1:
                    return "schema1";
                case Instances.I2:
                    return "schema2";
                case Instances.I3:
                    return "schema3";
                case Instances.I4:
                    return "schema4";
                case Instances.I5:
                    return "schema5";
                default:
                    return "public";
            }
        }

    }

    public MyDB(bool Proxy, Instances Instance)
        : base("MyDB")
    {
        this.Configuration.ProxyCreationEnabled = Proxy;
        this.Instance = Instance;

        this.Database.Log = s => System.Diagnostics.Debug.Print(s);

    }



    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {

        modelBuilder.HasDefaultSchema(Schema);
        modelBuilder.Conventions.Add(new FunctionsConvention<MyDB>(Schema));
    }

}
class NpgsqlConfiguration : DbConfiguration
{
    public NpgsqlConfiguration()
    {
        SetModelCacheKey(ctx => new EntityModelCacheKey((ctx.GetType().FullName + ctx.Database.Connection.ConnectionString).GetHashCode()));
        SetProviderServices("Npgsql", Npgsql.NpgsqlServices.Instance);
        SetProviderFactory("Npgsql", Npgsql.NpgsqlFactory.Instance);
        SetDefaultConnectionFactory(new Npgsql.NpgsqlConnectionFactory());
    }
}

Thanks for your help !

Answer 1

Its Simple use two connection strings

MyDB db;
if (user.Type == 1)
{
    db = new MyDb("nameOfConnectionString1");
}
else
{
    db = new MyDb("nameOfConnectionString2");
}

you may need to create overload for constructor

public MyDB(string conStr, bool Proxy, Instances Instance)
    : base(conStr)