EntityFramework Npgsql DbConfiguration 不起作用

Question

Im trying to configure EntityFramework with Npgsql with code first.

• EntityFramework 6.1.3
• Npgsql 3.0.5

Now, i want to set a custom configuration by a class, let's see:

public class DbConfig : DbConfiguration
{
    public DbConfig()
    {
        SetProviderFactory("Npgsql", Npgsql.NpgsqlFactory.Instance);
        SetProviderServices("Npgsql", provider: NpgsqlServices.Instance);
        SetDefaultConnectionFactory(new NpgsqlConnectionFactory());
    }
}

and my context class:

[DbConfigurationType(typeof(DbConfig))]
public class Db: DbContext
{
    public virtual DbSet<Products> Products {get;set;}

    public Db(DbConnection Connection): base(Connection, true)
    {

    }

    public Db(): base()
    {                       
    }

    public Db(string connectionString): base(connectionString)
    {            
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {

        modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();
        modelBuilder.Conventions.Add<CascadeDeleteAttributeConvention>();
        modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
        modelBuilder.HasDefaultSchema("public");
        base.OnModelCreating(modelBuilder);
    }
}

And I try to get access to Products:

class Program
{
    static void Main(string[] args)
    {
        Db.ConfigureMigrations();

        string connectionString = "Server=localhost;Port=5432;Database=stockDb;User Id=postgres;Password=123456;";                       

        using (var C = new Db(connectionString))
        {
            var productos = C.Productos.Count();
            Console.WriteLine(productos);
        }

        Console.WriteLine("listo");
        Console.ReadKey();
    }
}

But i have some exceptions:

• 'System.Data.Entity.Core.ProviderIncompatibleException' occurred in EntityFramework.dll. inner exception: {"The provider did not return a ProviderManifestToken string."}

or:

The format of the initialization string does not conform to specification starting at index 0.

And i don't know whats wrong.

I got reference:

https://msdn.microsoft.com/en-us/data/jj680699.aspx

csomeone can help me?

Answer 1

I solved this:

The problem is with Db.ConfigureMigrations(); line.

if i comment that line all right, but i need the migrations, then in my Db context in my ConfigureMigrations method i need to change for:

Database.SetInitializer(new MigrateDatabaseToLatestVersion(true));

And that'a all. Thanks.