Entity Framework and multiple schemas

Question

I\'m trying to set up my dbContext so that it can handle multiple schemas in a single Oracle database. I didn\'t want one monolithic dbContext file so I\'ve come up with the

Answer 1

You can specify schema per table via Table attribute.

[Table(nameof(MyTable1), Schema = "Schema1")]
public class MyTable1 { }

[Table(nameof(MyTable2), Schema = "Schema2")]
public class MyTable2 { }

Answer 2

Try using partial classes instead

public partial class oraDbContext : DbContext
{
    static oraDbContext() {
        Database.SetInitializer<oraDbContext>(null);
    }

    public oraDbContext(string connName)
        : base("Name=" + connName) { }

    protected override void OnModelCreating(DbModelBuilder modelBuilder) {
        schema1(modelBuilder);
        schema2(modelBuilder);
    }
}

public partial class oraDbContext : DbContext
{
    public DbSet<someTable> someTable { get; set; }
    void schema1(DbModelBuilder modelBuilder)
    {
        modelBuilder.Configurations.Add(new someTableMap());
    }
}

Answer 3

While doing some research about Entity Framework I came across the following post:

http://romiller.com/2011/05/23/ef-4-1-multi-tenant-with-code-first/

It doesn't quite give me a single dbContext to work with but it does only use a single connection (which was my reasoning behind not wanting to use multiple dbContexts). After setting up the following code:

public class oraDbContext : DbContext
{
    static oraDbContext() {
        Database.SetInitializer<oraDbContext>(null);
    }

    private oraDbContext(DbConnection connection, DbCompiledModel model)
        : base(connection, model, contextOwnsConnection: false) { }

    public DbSet<SomeTable1> SomeTable1 { get; set; }
    public DbSet<SomeTable2> SomeTable2 { get; set; }

    private static ConcurrentDictionary<Tuple<string, string>, DbCompiledModel> modelCache = new ConcurrentDictionary<Tuple<string, string>, DbCompiledModel>();

    public static oraDbContext Create(string schemaName, DbConnection connection) {
        var compiledModel = modelCache.GetOrAdd(
            Tuple.Create(connection.ConnectionString, schemaName),
            t =>
            {
                var builder = new DbModelBuilder();
                builder.Configurations.Add<SomeTable1>(new SomeTable1Map(schemaName));
                builder.Configurations.Add<SomeTable2>(new SomeTable2Map(schemaName));

                var model = builder.Build(connection);
                return model.Compile();
            });

        return new oraDbContext(connection, compiledModel);
    }
}

This of course requires that my mapping files be set up like so:

public class DailyDependencyTableMap : EntityTypeConfiguration<DailyDependencyTable>
{
    public SomeTableMap(string schemaName) {
        this.ToTable("SOME_TABLE_1", schemaName.ToUpper());

        //Map other properties and stuff
    }
}

Writing queries that use multiple schemas is somewhat annoying but, for the moment, it does what I need it to do:

using (var connection = new OracleConnection("a connection string")) {
    using (var schema1 = oraDbContext.Create("SCHEMA1", connection))
    using (var schema2 = oraDbContext.Create("SCHEMA2", connection)) {

        var query = ((from a in schema1.SomeTable1 select new { a.Field1 }).ToList())
             .Concat((from b in schema2.SomeTable1 select new { b.Field1 }).ToList())
    }
}