Multiple Database

By default only single database can be set in order to be used in all the ITGenericRepository implementations for each entity into BIA Framework from the appsettings.json of the API or Worker project :

appsettings.json

{
  "ConnectionStrings": {
    "ProjectDatabase": "data source=localhost;initial catalog=MyDatabase;integrated security=True;MultipleActiveResultSets=True;Encrypt=False;App=MyApplication"
  },
}

This page will explain how to use multiple database for your repositories inside the BIA Framework

Datacontext Factory

The DataContextFactory allows you to store different instances of IQueryableUnitOfWork as DataContext or provide a new instance of IQueryableUnitOfWorkNoTracking as DataContextNoTracking based on multiple database configurations set in the appsettings.json :

appsettings.json

{
  "ConnectionStrings": {
    "ProjectDatabase": "data source=localhost;initial catalog=MyDatabase;integrated security=True;MultipleActiveResultSets=True;Encrypt=False;App=MyApplication"
  },
  "DatabaseConfigurations": [
    {
      "Key": "ProjectSecondDatabase",
      "Provider": "SQLServer",
      "ConnectionString": "data source=localhost;initial catalog=MySecondDatabase;integrated security=True;MultipleActiveResultSets=True;Encrypt=False;App=MyApplication"
    },
    {
      "Key": "ProjectThirdDatabase",
      "Provider": "SQLServer",
      "ConnectionString": "data source=localhost;initial catalog=MyThirdDatabase;integrated security=True;MultipleActiveResultSets=True;Encrypt=False;App=MyApplication"
    }
  ]
}

For each new scope, the DataContextFactory will create and store the instances of IQueryableUnitOfWork as DataContext with the provided key of your configuration :

DataContextFactory.cs

namespace MyCompany.MyProject.Infrastructure.Data
{
    public class DataContextFactory
    {
        private readonly IServiceProvider serviceProvider;
        private readonly IConfiguration configuration;
        private readonly Dictionary<string, IQueryableUnitOfWork> queryableUnitOfWorks = new ();
        private readonly List<DatabaseConfiguration> databaseConfigurations;

        public DataContextFactory(IServiceProvider serviceProvider, IConfiguration configuration)
        {
            this.serviceProvider = serviceProvider;
            this.configuration = configuration;
            this.databaseConfigurations = configuration.GetSection("DatabaseConfigurations").Get<List<DatabaseConfiguration>>();
            this.FillQueryableUnitOfWorks();
        }

        private void FillQueryableUnitOfWorks()
        {
            foreach (var databaseConfiguration in this.databaseConfigurations)
            {
                var queryableUnitOfWork = this.CreateDataContext(databaseConfiguration);
                this.queryableUnitOfWorks.TryAdd(databaseConfiguration.Key, queryableUnitOfWork);
            }
        }

        private DataContext CreateDataContext(DatabaseConfiguration databaseConfiguration)
        {
            var dataContextLogger = this.serviceProvider.GetRequiredService<ILoggerFactory>().CreateLogger<DataContext>();
            var dataContextOptions = new DbContextOptionsBuilder<DataContext>();
            ConfigureDataContextOptionsProvider(databaseConfiguration, dataContextOptions);
            dataContextOptions.EnableSensitiveDataLogging();
            dataContextOptions.AddInterceptors(new AuditSaveChangesInterceptor());
            return new DataContext(dataContextOptions.Options, dataContextLogger, this.configuration);
        }

        private static void ConfigureDataContextOptionsProvider(DatabaseConfiguration databaseConfiguration, DbContextOptionsBuilder<DataContext> dataContextOptions)
        {
            switch (databaseConfiguration.Provider.ToLower())
            {
                case "sqlserver":
                    dataContextOptions.UseSqlServer(databaseConfiguration.ConnectionString);
                    break;
                case "postgresql":
                    dataContextOptions.UseNpgsql(databaseConfiguration.ConnectionString);
                    break;
                default:
                    throw new NotImplementedException($"Provider {databaseConfiguration.Provider} not handled.");
            }
        }
    }
}

The instances will be available by requesting the GetQueryableUnitOfWork method with the required key of the database :

DataContextFactory.cs

public IQueryableUnitOfWork GetQueryableUnitOfWork(string key)
{
    if (this.queryableUnitOfWorks.TryGetValue(key, out IQueryableUnitOfWork unitOfWork))
    {
        return unitOfWork;
    }

    throw new InvalidOperationException($"Unable to find {nameof(IQueryableUnitOfWork)} with key {key}");
}

You can request a new implementation of IQueryableUnitOfWorkNoTracking with the following method :

DataContextFactory.cs

public IQueryableUnitOfWorkNoTracking GetQueryableUnitOfWorkNoTracking(string key)
{
    var databaseConfiguration = this.databaseConfigurations.Find(x => x.Key == key)
        ?? throw new InvalidOperationException($"Unable to find {nameof(DatabaseConfiguration)} with key {key}");

    return this.CreateDataContextNoTracking(databaseConfiguration);
}

private DataContextNoTracking CreateDataContextNoTracking(DatabaseConfiguration databaseConfiguration)
{
    var dataContextLogger = this.serviceProvider.GetRequiredService<ILoggerFactory>().CreateLogger<DataContextNoTracking>();
    var dataContextOptions = new DbContextOptionsBuilder<DataContext>();
    ConfigureDataContextOptionsProvider(databaseConfiguration, dataContextOptions);
    dataContextOptions.EnableSensitiveDataLogging();
    return new DataContextNoTracking(dataContextOptions.Options, dataContextLogger, this.configuration);
}

The DataContextFactory is injected as scoped into the IOC container.

NOTE : You can create your own factory with your own contexts and configurations. The DataContextFactory is only applicable for the DataContext instances.

Database Repository

Once the DataContextFactory created, you will now use it to build the repository of an entity that will need one of your multiple database.

Instead inherit directly from TGenericRepositoryEF<TEntity, TKey>, your custom repository must inherit from DatabaseRepositoryBase<TEntity, TKey> (that inherits herself from TGenericRepositoryEF<TEntity, TKey>).
Create all your database repositories into the Infrastructure.Data project inside the Repositories folder.

You'll must fill the key of your database in the base constructor to use with the DataContextFactory to retrieve the instance of the IQueryableUnitOfWork to use with your repository :

MySecondDatabaseRepository

namespace MyCompany.MyProject.Infrastructure.Data.Repositories
{
    public class MySecondDatabaseRepository<TEntity, TKey> : DatabaseRepositoryBase<TEntity, TKey>, IMySecondDatabaseRepository<TEntity, TKey>
        where TEntity : class, IEntity<TKey>
    {
        public MySecondDatabaseRepository(DataContextFactory dataContextFactory, IServiceProvider serviceProvider)
            : base(dataContextFactory, serviceProvider, "ProjectSecondDatabase")
        {
        }
    }
}

Don't forget to declare the corresponding interface into the Domain project inside RepoContract folder :

IMySecondDatabaseRepository

namespace MyCompany.MyProject.Domain.RepoContract
{
    public interface IMySecondDatabaseRepository<TEntity, TKey> : ITGenericRepository<TEntity, TKey>
        where TEntity : class, IEntity<TKey>
    {
    }
}

You can know use your repository like other one by injecting it into your application services :

MyEntityService

namespace MyCompany.MyProject.Application.MyEntity
{
    public class MyEntityAppService : CrudAppServiceBase<MyEntityDto, MyEntity, int, PagingFilterFormatDto, MyEntityMapper>, IMyEntityAppService
    {
        public MyEntityAppService(IMySecondDatabaseRepository<MyEntity, int> repository)
            : base(repository)
        {
        }
    }
}