In C#, MVC code first application I have
public class CarContext : DbContext { }
class in first version of application. And connection string is like
<add name="CarContext" providerName="System.Data.SqlClient" Integrated Security=true;
connectionString="Data Source=Dragon; Initial Catalog=CarDBv1;"/>
When I run application, first version of database is created - CarDBv1.
Then I edit my CarContext class, for example, add new table, change any property etc., also change version of application, change connection string
Initial Catalog=CarDBv1; to Initial Catalog=CarDBv2; and run project. In this case I have 2 database: CarDBv1 and CarDBv2. But, CarContext class is same in applications.
Now, I need to connect both database and their context(CarContext) from any console application and use their tables for converting, reading etc.
I found a similar answer here: https://stackoverflow.com/a/16860878/1534785
But in my applications context name is same.
How can I create 2 instances for every CarContext in applications by their database connection string?
You can use an overloaded constructor to DbContext to allow contexts to point at and arbitrary database which is NOT declared in app.config.
See the constructor with dbConnection.
public class MyDbContext : DbContext, IContextOptions {
//ctors
protected BosBaseDbContext(string connectionName)
: base(connectionName) { }
protected BosBaseDbContext(DbConnection dbConnection, bool contextOwnsConnection)
: base(dbConnection, contextOwnsConnection) { }
}
usage
//datasource could be localhost, DBName the catalog name
new MyDbContext((GetSqlConn4DbName(dataSource,dbName )),true);
public DbConnection GetSqlConn4DbName(string dataSource, string dbName) {
var sqlConnStringBuilder = new SqlConnectionStringBuilder();
sqlConnStringBuilder.DataSource = String.IsNullOrEmpty(dataSource) ? DefaultDataSource : dataSource;
sqlConnStringBuilder.IntegratedSecurity = true;
sqlConnStringBuilder.MultipleActiveResultSets = true;
var sqlConnFact = new SqlConnectionFactory(sqlConnStringBuilder.ConnectionString);
var sqlConn = sqlConnFact.CreateConnection(dbName);
return sqlConn;
}
Related
When setting up a MartenDB datastore in ASP.Net Core, you normally put code like this in your Startup.cs:
services.AddMarten(o =>
{
o.Connection(configuration.GetConnectionString("MyDatabase"));
o.AutoCreateSchemaObjects = AutoCreate.All;
o.Serializer(new JsonNetSerializer { EnumStorage = EnumStorage.AsString });
});
This allows you to then inject IDocumentSession and IDocumentStore into your various classes for working with that database.
Now what do you do if you have to connect to a second database? I looked at the ISessionFactory but it is not apparent that you can change the connection string from here. Do you need to manually create and register a new DocumentStore?
To answer my own question, I wound up creating a custom DocumentStore and ISessionFactory for each database I wanted to connect to, and then injecting the custom SessionFactory.
Here's the code (only showing one instance of each class for the sake of brevity. Just replace Db1 with Db2 for the second version of each class):
The custom DocumentStore:
public class Db1Store : DocumentStore
{
public Db1Store(StoreOptions options) : base(options)
{
}
}
The custom SessionFactory:
public class Db1SessionFactory : ISessionFactory
{
private readonly Db1Store store;
public Db1SessionFactory(Db1Store store)
{
this.store = store;
}
public IQuerySession QuerySession()
{
return store.QuerySession();
}
public IDocumentSession OpenSession()
{
return store.OpenSession();
}
}
The service registration (this replaces the services.AddMarten call):
services.AddSingleton(p =>
{
var options = new StoreOptions();
options.Connection(configuration.GetConnectionString("DB1"));
options.AutoCreateSchemaObjects = AutoCreate.All;
options.Serializer(new JsonNetSerializer { EnumStorage = EnumStorage.AsString });
return new Db1Store(options);
});
services.AddSingleton<Db1SessionFactory>();
Then you inject the Db1SessionFactory instance into your class, and run a query like this:
var result = await db1SessionFactory.QuerySession().Query<MyAwesomeTable>().ToListAsync();
Downsides:
I would prefer to inject the QuerySession or DocumentSession, but I can't see a way to do that without moving to Autofac or a similar DI Container that supports named instances.
I am not sure what downsides there will be creating these QuerySession/DocumentSessions in this manner. It may be a bad tradeoff.
PLEASE READ THE EDIT SECTION, IT CAN HELP ME TO CLARIFY THE QUESTION
I have this structure right now:
WebApp.csproj
Application.csproj
Data.csproj
Oracle.csproj
SqlServer.csproj
My Data (3) is just a project referenced by WebApp (1) to decides which one (4 or 5) should be called based on the web.config.
If the web.config contains the app.key DBaseDL with 'oracle' value, it should LoadAssembly 4, instead, assembly 5.
Classes of 4 and 5 are mirror but with the query on each syntax (4 has syntax for oracle and 5 for sql server). Those mirror classes implements a commom interface between then, like this:
namespace MyProject.Oracle
{
public class User : IUser
{
//...
}
}
namespace MyProject.SqlServer
{
public class User : IUser
{
//...
}
}
On Data (3) csproj I'm trying to create a Factory which creates the User class from 4 or 5, based on the web.config settings like I said before. So I do something like this:
public class UserDataFactory : IDataLayerFactory<IUser>
{
private readonly string _key;
public UserDataFactory(string key)
{
_key = key;
}
public IUser Create()
{
string strPath = string.Empty;
string strClassName = string.Empty;
string strAssemblyName = string.Empty;
string strVersion = Assembly.GetExecutingAssembly().GetName().Version.ToString();
if (_key.Equals("oracle"))
strAssemblyName = "MyProjejct.Oracle";
else
strAssemblyName = "MyProject.SQLServer";
strPath = strAssemblyName + ", Version=" + strVersion + ", Culture=neutral, PublicKeyToken=xxxxxxx";
strClassName = strAssemblyName + ".User";
return (IUser)Assembly.Load(strPath).CreateInstance(strClassName);
}
}
My problem starts on this IDataFactory class.
I already did everything works with forced values (like always on SQLServer or Oracle) but not with IoC + the settings key for database.
I'm trying to do something like this with AutoFac but I'm probably missing something and I'm blind.
public static void ConfigureContainer()
{
var builder = new ContainerBuilder();
builder.RegisterControllers(Assembly.GetExecutingAssembly()).InstancePerRequest();
builder.RegisterType<Mediator>().As<IMediator>().InstancePerLifetimeScope();
builder.RegisterType<AutofacValidatorFactory>().As<IValidatorFactory>().SingleInstance();
builder.RegisterType<AutofacDataLayerFactory>().As<IDataFactory>().InstancePerLifetimeScope();
builder.RegisterType<FluentValidationModelValidatorProvider>().As<ModelValidatorProvider>();
builder.RegisterType<RegistryManagerService>().As<IRegistryManagerService>().SingleInstance().WithParameter("appName", ConfigurationManager.AppSettings["APPNAME"]);
builder.Register<ServiceFactory>(context =>
{
var c = context.Resolve<IComponentContext>();
return t => c.Resolve(t);
});
builder.RegisterAssemblyTypes(Assembly.Load("MyProj.Application"))
.Where(x => x.Name.EndsWith("Handler"))
.AsImplementedInterfaces();
builder.RegisterAssemblyTypes(Assembly.Load("MyProj.Application"))
.Where(x => x.Name.EndsWith("Validator"))
.AsImplementedInterfaces()
.InstancePerLifetimeScope();
builder.RegisterAssemblyTypes(Assembly.Load("MyProj.Application"))
.Where(x => x.Name.EndsWith("DataFactory"))
.AsImplementedInterfaces()
.InstancePerLifetimeScope();
var container = builder.Build();
DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
}
}
Just to say, IDataFactory is about User now, but it will be a lot of things, and I don't want to register for every class again on autofac. I'm trying to register all my IDataFactory so the constructor of my handlers on Application.csproj should get the already created by factory classes, the DataAccess object from Oracle or SqlServer.
Can someone help me?
EDIT
After digging and learning a little more about the AutoFac, IoC and DI, I realize a easy way to register my class, but I'm pretty sure there is a better and more ellegant solution then mine.
I just read the key from configuration manager and write this code at the AutoFacConfig file:
if (key == "oracle")
builder.RegisterType<DocspiderOracleDbService>().As<IDocspiderDbService>().InstancePerRequest();
else
builder.RegisterType<DocspiderSqlServerDbService>().As<IDocspiderDbService>().InstancePerRequest();
This worked because only the service from the correct database is registered, but, I'll keep digging how to make it the right away.
If anyone have an idea, I'll be greatfull.
Problem:
I have webapi serviss where almost every user has its own database instance to connect. So i have to set different connection string for each user. To recognize user i will pass specific Token into header. Regarding on this Token, system has to build and set differenct connection string into Data Access layer constructor (Order in this case)
Question:
Is it possible to pass argument to Ninject or any kind of IoC binder regarding on request header?
IOrders _orders;
public HomeController(IOrders order)
{
_orders = order;
}
Here is an Ninject binding, but as you can guess, HttpContext.Current is null.
private static void RegisterServices(IKernel kernel)
{
var some_value = HttpContext.Current.Request.Headers.GetValues("Token");
kernel.Bind<IOrders>()
.To<Orders>()
.WhenInjectedInto<HomeController>()
.WithConstructorArgument("Token", some_value);
}
Maybe there is much elegant way to do this using Controller Factory ?
I would create a service class that does this lookup for you. then inject this service into the Orders implementation.
public interface IRequestContext {
string ConnectionString {get;}
}
public class HttpHeaderRequestContext : IRequestContext {
public string ConnectionString {
get {
var token = HttpContext.Current.Request.Headers.GetValues("Token");
// .. lookup conn string based on token
}
}
}
public class Orders : IOrders {
public Orders(IRequestContext ctx) {
// create new connection w/ ctx.ConnectionString
}
}
using this method, the lookup of headers and connection strings is abstracted away from the implementation. this makes it easier to test and easier swap out with a different method of obtaining a connection string if the need arises.
After implementing Dave approach, i realized that i could solve this connection string injection by feeding HttpContext.Current into Ninject binding like this:
private static void RegisterServices(IKernel kernel)
{
kernel.Bind<IOrders>()
.To<Orders>()
.WhenInjectedInto<HomeController>()
.WithConstructorArgument("smth", x => {
var token = HttpContext.Current.Request.Headers.Get("Token");
var _db = new SomeDataCxt();
var connStr = _db.DbStringRepository.GetByToken(token);
return connStr;
});
}
I'm building a multi-tenant web application where for security concerns, we need to have one instance of the database per tenant. So I have a MainDB for authentication and many ClientDB for application data.
I am using Asp.net MVC with Ninject and Fluent nHibernate. I have already setup my SessionFactory/Session/Repositories using Ninject and Fluent nHibernate in a Ninject Module at the start of the application. My sessions are PerRequestScope, as are repositories.
My problem is now I need to instanciate a SessionFactory (SingletonScope) instance for each of my tenants whenever one of them connects to the application and create a new session and necessary repositories for each webrequest. I'm puzzled as to how to do this and would need a concrete example.
Here's the situation.
Application starts : The user of TenantX enters his login info. SessionFactory of MainDB gets created and opens a session to the MainDB to authenticate the user. Then the application creates the auth cookie.
Tenant accesses the application : The Tenant Name + ConnectionString are extracted from MainDB and Ninject must construct a tenant specific SessionFactory (SingletonScope) for that tenant. The rest of the web request, all controllers requiring a repository will be inject with a Tenant specific session/repository based on that tenant's SessionFactory.
How do I setup that dynamic with Ninject? I was originally using Named instance when I had multiple databases but now that the databases are tenant specific, I'm lost...
After further research I can give you a better answer.
Whilst it's possible to pass a connection string to ISession.OpenSession a better approach is to create a custom ConnectionProvider. The simplest approach is to derive from DriverConnectionProvider and override the ConnectionString property:
public class TenantConnectionProvider : DriverConnectionProvider
{
protected override string ConnectionString
{
get
{
// load the tenant connection string
return "";
}
}
public override void Configure(IDictionary<string, string> settings)
{
ConfigureDriver(settings);
}
}
Using FluentNHibernate you set the provider like so:
var config = Fluently.Configure()
.Database(
MsSqlConfiguration.MsSql2008
.Provider<TenantConnectionProvider>()
)
The ConnectionProvider is evaluated each time you open a session allowing you to connect to tenant specific databases in your application.
An issue with the above approach is that the SessionFactory is shared. This is not really a problem if you are only using the first level cache (since this is tied to the session) but is if you decide to enable the second level cache (tied to the SessionFactory).
The recommended approach therefore is to have a SessionFactory-per-tenant (this would apply to schema-per-tenant and database-per-tenant strategies).
Another issue often overlooked is that although the second level cache is tied to the SessionFactory, in some cases the cache space itself is shared (reference). This can be resolved by setting the "regionName" property of the provider.
Below is a working implementation of SessionFactory-per-tenant based on your requirements.
The Tenant class contains the information we need to set up NHibernate for the tenant:
public class Tenant : IEquatable<Tenant>
{
public string Name { get; set; }
public string ConnectionString { get; set; }
public bool Equals(Tenant other)
{
if (other == null)
return false;
return other.Name.Equals(Name) && other.ConnectionString.Equals(ConnectionString);
}
public override bool Equals(object obj)
{
return Equals(obj as Tenant);
}
public override int GetHashCode()
{
return string.Concat(Name, ConnectionString).GetHashCode();
}
}
Since we'll be storing a Dictionary<Tenant, ISessionFactory> we implement the IEquatable interface so we can evaluate the Tenant keys.
The process of getting the current tenant is abstracted like so:
public interface ITenantAccessor
{
Tenant GetCurrentTenant();
}
public class DefaultTenantAccessor : ITenantAccessor
{
public Tenant GetCurrentTenant()
{
// your implementation here
return null;
}
}
Finally the NHibernateSessionSource which manages the sessions:
public interface ISessionSource
{
ISession CreateSession();
}
public class NHibernateSessionSource : ISessionSource
{
private Dictionary<Tenant, ISessionFactory> sessionFactories =
new Dictionary<Tenant, ISessionFactory>();
private static readonly object factorySyncRoot = new object();
private string defaultConnectionString =
#"Server=(local)\sqlexpress;Database=NHibernateMultiTenancy;integrated security=true;";
private readonly ISessionFactory defaultSessionFactory;
private readonly ITenantAccessor tenantAccessor;
public NHibernateSessionSource(ITenantAccessor tenantAccessor)
{
if (tenantAccessor == null)
throw new ArgumentNullException("tenantAccessor");
this.tenantAccessor = tenantAccessor;
lock (factorySyncRoot)
{
if (defaultSessionFactory != null) return;
var configuration = AssembleConfiguration("default", defaultConnectionString);
defaultSessionFactory = configuration.BuildSessionFactory();
}
}
private Configuration AssembleConfiguration(string name, string connectionString)
{
return Fluently.Configure()
.Database(
MsSqlConfiguration.MsSql2008.ConnectionString(connectionString)
)
.Mappings(cfg =>
{
cfg.FluentMappings.AddFromAssemblyOf<NHibernateSessionSource>();
})
.Cache(c =>
c.UseSecondLevelCache()
.ProviderClass<HashtableCacheProvider>()
.RegionPrefix(name)
)
.ExposeConfiguration(
c => c.SetProperty(NHibernate.Cfg.Environment.SessionFactoryName, name)
)
.BuildConfiguration();
}
private ISessionFactory GetSessionFactory(Tenant currentTenant)
{
ISessionFactory tenantSessionFactory;
sessionFactories.TryGetValue(currentTenant, out tenantSessionFactory);
if (tenantSessionFactory == null)
{
var configuration = AssembleConfiguration(currentTenant.Name, currentTenant.ConnectionString);
tenantSessionFactory = configuration.BuildSessionFactory();
lock (factorySyncRoot)
{
sessionFactories.Add(currentTenant, tenantSessionFactory);
}
}
return tenantSessionFactory;
}
public ISession CreateSession()
{
var tenant = tenantAccessor.GetCurrentTenant();
if (tenant == null)
{
return defaultSessionFactory.OpenSession();
}
return GetSessionFactory(tenant).OpenSession();
}
}
When we create an instance of NHibernateSessionSource we set up a default SessionFactory to our "default" database.
When CreateSession() is called we get a ISessionFactory instance. This will either be the default session factory (if the current tenant is null) or a tenant specific session factory. The task of locating the tenant specific session factory is performed by the GetSessionFactory method.
Finally we call OpenSession on the ISessionFactory instance we have obtained.
Note that when we create a session factory we set the SessionFactory name (for debugging/profiling purposes) and cache region prefix (for the reasons mentioned above).
Our IoC tool (in my case StructureMap) wires everything up:
x.For<ISessionSource>().Singleton().Use<NHibernateSessionSource>();
x.For<ISession>().HttpContextScoped().Use(ctx =>
ctx.GetInstance<ISessionSource>().CreateSession());
x.For<ITenantAccessor>().Use<DefaultTenantAccessor>();
Here NHibernateSessionSource is scoped as a singleton and ISession per request.
Hope this helps.
If all the databases are on the same machine, maybe the schema property of class mappings could be used to set the database on a pre-tenant basis.
I've got an Asp.net Mvc 3 Application which is now using the MvcMiniProfiler. I'm also using the Entity Framework to access my database, and I'd like to enable the profiler to work with the entity model. So far I've created the Context factory below:
internal class ProfiledContextFactory : IContextFactory
{
public ModelContainer GetContext()
{
var conn = ProfiledDbConnection.Get(GetConnection());
return ObjectContextUtils.CreateObjectContext<ModelContainer>(conn);
}
private static EntityConnection GetConnection()
{
return new EntityConnection(ConfigurationManager.ConnectionStrings["ModelContainer"].ConnectionString);
}
}
When I run the above code, which is called by my repository layer when I start a unit of work, it gets stuck in an infite loop when calling CreateDbCommandDefinition in the MvcMiniProfiler.ProfiledDbServices class.
Any clues what I'm doing wrong?
The problem was my GetConnection was returning the EntityConnection, not the SqlConnection within the EntityConnection. I've now modified my code so that it reads:
private static SqlConnection GetConnection()
{
var connStr = ConfigurationManager.ConnectionStrings["ModelContainer"].ConnectionString;
var entityConnStr = new EntityConnectionStringBuilder(connStr);
return new SqlConnection(entityConnStr.ProviderConnectionString);
}
And it works fine.
I discovered this while looking at this question: Using mvc-mini-profiler with EF 4.0 and Ninject