How to register multiple IDbConnectionFactory instances using Funq in ServiceStack.net part 2

Question

ServiceStack has delivered on EVERYTHING I've thrown at it, except the SAAS (Multi-tenant) use case where single API instance is using several databases of the same schema, one per tenant. These databases, because of legal reasons need to be housed in separate instances.

So, my question is this, "Is it possible to change the connection per Request based on meta from a filter?

My question is somewhat similar to this one, but with the added twist that each database is the same.

Thank you, Stephen

Edit: If memory serves me correctly I think mythz and I have discussed this before and found that even if we were able to get the ADO connection to change, the IAuthRepository is then broken. So it's not feasible.

Answer 1

I've added an example Multi Tenant test showing my preferred approach where I would use a custom IDbConnectionFactory wrapper so I have better visibility and control of the Db Connections being created, i.e:

public class MultiTenantDbFactory : IDbConnectionFactory
{
    private readonly IDbConnectionFactory dbFactory;

    public MultiTenantDbFactory(IDbConnectionFactory dbFactory)
    {
        this.dbFactory = dbFactory;
    }

    public IDbConnection OpenDbConnection()
    {
        var tenantId = RequestContext.Instance.Items["TenantId"] as string;
        return tenantId != null
            ? dbFactory.OpenDbConnectionString(GetConnectionString(tenantId))
            : dbFactory.OpenDbConnection();
    }

    public IDbConnection CreateDbConnection()
    {
        return dbFactory.CreateDbConnection();
    }
}

I'll also prefer to have a master dbFactory singleton instance to use as a default for non-tenant requests which also specifies which Dialect Provider to use:

var dbFactory = new OrmLiteConnectionFactory(
    AppSettings.GetString("MasterDb"), SqlServerDialect.Provider);

container.Register<IDbConnectionFactory>(c =>
    new MultiTenantDbFactory(dbFactory));

To indicate that a Service is tenant-specific, I'll just create a custom interface:

public interface IForTenant
{
    string TenantId { get; }
}

Which Request DTO's can implement to indicate they're tenant-specific requests, i.e:

public class GetTenant : IForTenant, IReturn<GetTenantResponse>
{
    public string TenantId { get; set; }
}

Which can be easily detected throughout ServiceStack's Request pipeline like a Global Request Filter to pull out what tenant the request is for and add it to the RequestContext, e.g:

GlobalRequestFilters.Add((req, res, dto) =>
{
    var forTennant = dto as IForTenant;
    if (forTennant != null)
        RequestContext.Instance.Items.Add("TenantId", forTennant.TenantId);
});

The MultiTenantDbFactory can then read this back and open the Db Connection to the desired tenant:

var tenantId = RequestContext.Instance.Items["TenantId"] as string;
return new OrmLiteConnectionFactory(GetConnectionStringFor(tenantId))
    .OpenDbConnection()

Which will be used whenever anyone accesses base.Db in their services or dependencies.