With MVC & EF6 Code first approach I am able to integrate Azure MSI token & performing CRUD operation but how do I perform migration for which I have to inject token into DBContext:
Connection String:
For peforming CRUD query I use legacy ADO.NET style query as below and it works:
Getting MSI :
In order to run migration, how do I pass Azure MSI AccessToken into DbContext contructor.
For dbcontext i have to define separate connection string with provider name.
You need to setup in your DI:
Startup.cs
public void ConfigureServices(IServiceCollection services)
{
//code ignored for simplicity
services.AddDbContext<AzureProvider>();
services.AddTransient<IDBAuthTokenService, AzureSqlAuthTokenService>();
}
DbContext
public partial class AzureProvider: DbContext
{
public IConfiguration Configuration { get; }
public IDBAuthTokenService authTokenService { get; set; }
public AzureProvider(IConfiguration configuration, IDBAuthTokenService tokenService, DbContextOptions<AzureProvider> options)
: base(options)
{
Configuration = configuration;
authTokenService = tokenService;
}
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
SqlConnection connection = new SqlConnection();
connection.ConnectionString = Configuration.GetConnectionString("defaultConnection");
connection.AccessToken = authTokenService.GetToken().Result;
optionsBuilder.UseSqlServer(connection);
}
}
public class AzureSqlAuthTokenService : IDBAuthTokenService
{
public async Task<string> GetToken()
{
AzureServiceTokenProvider provider = new AzureServiceTokenProvider();
var token = await provider.GetAccessTokenAsync("https://database.windows.net/");
return token;
}
}
EF Core Connection to Azure SQL with Managed Identity
This is how I did AAD token authentication for Azure SQL using Entity Framework 6 and .NET Framework for anyone that comes across this question.
public class MyContext : DbContext
{
public MyContext() : base(CustomAzureSQLAuthProvider.GetTokenConnection("MyConnectionStringName"), true)
{
}
//...
}
public class CustomAzureSQLAuthProvider
{
private static readonly string[] azureSqlScopes = new[]
{
"https://database.windows.net//.default"
};
private static readonly TokenCredential credential = new DefaultAzureCredential();
public static DbConnection GetTokenConnection(string connectionStringName)
{
var connectionStringSettings = ConfigurationManager.ConnectionStrings[connectionStringName];
var dbConnection = DbProviderFactories
.GetFactory(connectionStringSettings.ProviderName)
.CreateConnection();
dbConnection.ConnectionString = connectionStringSettings.ConnectionString;
var tokenRequestContext = new TokenRequestContext(azureSqlScopes);
var tokenResult = credential.GetToken(tokenRequestContext, default);
SqlConnection sqlConnection = dbConnection as SqlConnection;
sqlConnection.AccessToken = tokenResult.Token;
return sqlConnection;
}
}
Note: I had to use the non-async GetToken function. It did not work with GetTokenAsync.
I reproduced a way to access the database with .net Framework but it doesn't work in .net Core. I found a way to fix it and followed what was said but I get the error that the connectionString is not initialized. Therefore, I don't know how to get it working.
Code I'm using:
public class DataAccess
{
private string _connectionString;
public DataAccess(string connectionString)
{
_connectionString = connectionString;
}
public List<PropertyModel> LoadData()
{
var data = new List<PropertyModel>();
using(IDbConnection cnn = new SqlConnection(_connectionString))
{
data = cnn.Query<PropertyModel>(#"select *
from dbo.PropertyModel;").ToList();
}
return data;
}
}
In Controller:
private DataAccess data;
public PropertyController(IOptions<ConnectionConfig> connectionConfig)
{
var connection = connectionConfig.Value;
string connectionString = connection.Analysis;
data = new DataAccess(connectionString);
}
public IActionResult Index()
{
var test = data.LoadData();
return View();
}
In StartUp:
services.Configure<ConnectionConfig
(Configuration.GetSection("MVCCoreAppDB"));
And I created a POCO class:
public class ConnectionConfig
{
public string Analysis { get; set; }
}
I followed this.
appsettings.json:
"ConnectionStrings": {
"MVCCoreAppDB": "Data Source=(localdb)\\MSSQLLocalDB;Initial Catalog=MVCCoreAppDB;Integrated Security=True;Connect Timeout=60;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False"},
You are calling the wrong section from configuration.
services.Configure<ConnectionConfig>(Configuration.GetSection("ConnectionStrings"));
You would also need to update the model
public class ConnectionConfig {
public string MVCCoreAppDB { get; set; }
}
That said I would suggest you change your design to populate the model upfront and register it with the service collection for injection
In StartUp:
services.AddScoped<DataAccess>(_ =>
new DataAccess(Configuration.GetConnectionString("MVCCoreAppDB"))
);
And inject the data access explicitly into the controller
private readonly DataAccess data;
public PropertyController(DataAccess data) {
this.data = data;
}
public IActionResult Index() {
var test = data.LoadData();
return View();
}
Reference Explicit Dependencies Principle
Here is my method :
public async task<model> GetMemberList(CancellationToken cancelToken, string connString)
{
try
{
await Task.Run(() =>
{
using (var dbContext = DbContext.Create(connString))
{
// Code Goes Here....
}
}, cancelToken);
}
catch
{
Throw New Exception();
}
}
In here i used "using" keyword to get dbContext. In every methods I did this because we have different connection string. I hope this is not a bad way to write methods in entity framwork. I realized this when I was going to write unit test for each methods in the business layer. I want to write a constructor to get dbcontext in generic way. I can use Dependency Injection to do that but i don't know how to do that. Can someone give me a way to do it?
Create and Interface IDbFactory
public interface IDbFactory
{
DbContext GetConnection();
}
Create a class DbFactory
public class DbFactory : IDbFactory
{
public DbContext GetConnection()
{
var connectionString = [get this from web.config]
return new DbContext.Create(connectionString);
}
}
Inject dependacny for IDbFactory in the constructor then
public async task<model> GetMemberList(CancellationToken cancelToken)
{
try
{
await Task.Run(() =>
{
using (var db = _dbFactory.GetConnection())
{
// Code Goes Here....
}
}, cancelToken);
}
catch
{
Throw New Exception();
}
}
Hope it helps
If you just need to hide the logic of building connections string, you can use Factory pattern as it is. In this example building of connection string depends of clientId and is encapsulted in factory. You can mock it as you like in your unit tests for SomeService.
public class CompositionRoot
{
private readonly IContainer _root;
public CompositionRoot()
{
var builder = new ContainerBuilder();
builder.RegisterType<SomeService>();
builder.RegisterType<DbContextFactory>().As<IDbContextFactory>();
_root = builder.Build();
}
public T GetService<T>()
{
return _root.Resolve<T>();
}
}
public interface IDbContextFactory
{
DbContext Get(int clientId);
}
public class DbContextFactory : IDbContextFactory
{
public DbContext Get(int clientId)
{
// place here any logic you like to build connection string
var connection = $"Data Source={clientId}db";
return new DbContext(new SqlConnection(connection), true);
}
}
public class SomeService
{
private readonly IDbContextFactory _dbFactory;
public SomeService(IDbContextFactory dbFactory)
{
_dbFactory = dbFactory ?? throw new ArgumentNullException(nameof(dbFactory));
}
public async Task<Model> GetMemberList(CancellationToken cancelToken, int clientId)
{
using (var dbContext = _dbFactory.Get(clientId))
{
// Code Goes Here....
}
return null;
}
}
I'm trying out asp.net out and I'm having issues doing the simplest thing, connecting to a database. I have no clue how to call my context via dependency injection to use in my repository, if anyone can help me out it would be great. Here is my code:
Model:
public class User
{
...attrs...
}
Interface / Repo:
public interface UserRepository
{
List<User> GetUsers();
}
public class UserRepositoryImpl : UserRepository
{
public List<User> GetUsers()
{
//I NEED THE CONTEXT FOR "db" HERE!
using (MySqlConnection con = db.GetConnection())
{
List<User> list = new List<User>();
con.Open();
MySqlCommand cmd = new MySqlCommand("SELECT * FROM user", con);
using (MySqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
list.Add(new User()
{
...read stuff...
});
}
}
return list;
}
}
}
My Context:
public class MyContext
{
public string ConnectionString { get; set; }
public MyContext(string connectionString)
{
this.ConnectionString = connectionString;
}
public MySqlConnection GetConnection()
{
return new MySqlConnection(ConnectionString);
}
}
Service registration:
services.Add(new ServiceDescriptor(typeof(MyContext), new MyContext(Configuration.GetConnectionString("DefaultConnection"))));
Most tutorials either force me to use EF and others don't do the dependency injection, if anyone could guide me or point me to the right direction I would be really greatful! Thanks in advance!
EDIT: I got it to work using this in my controller after creating a constructor that takes in the context for my db:
[Produces("application/json")]
[Route("api/user")]
public class UserController : Controller
{
[HttpGet]
public List<User> AllUsers()
{
MyContext db = HttpContext.RequestServices.GetService(typeof(MyContext)) as MyContext;
UserRepositoryImpl repo = new UserRepositoryImpl(db);
return repo.GetUsers();
}
}
I still believe this can be improved though, is there a better way to do this? Thanks
EDIT2: Finally got it to work using this controller
[Produces("application/json")]
[Route("api/user")]
public class UserController : Controller
{
MyContext db;
public UserController(MyContext db)
{
this.db = db;
}
[HttpGet]
public List<User> AllUsers()
{
UserRepository repo = new UserRepository(db);
return repo.GetUsers();
}
}
Thanks to Tseng's answer!
I'm using Entity Framework 5 with Code First Migrations. I have a DataStore class which derives from DbContext:
public class DataStore : DbContext, IDataStore
{
public int UserID { get; private set; }
public DataStore(int userId, string connectionString) : base(connectionString)
{
UserID = userId;
}
public virtual IDbSet<User> Users { get; set; }
// Rest of code here
}
And a factory class which creates instances of the DataStore class:
public class DataStoreFactory : Disposable, IDataStoreFactory
{
private DataStore _database;
private int _userId;
private string _connectionString;
public DataStoreFactory(int userId, string connectionString)
{
_userId = userId;
_connectionString = connectionString;
}
public IDataStore Get()
{
_database = new DataStore(_userId, _connectionString);
return _database;
}
protected override void DisposeCore()
{
if (_database != null) _database.Dispose();
}
}
These classes have their constructor parameters injected at runtime with Unity. So far so good, everything works great!
The problem arises when we get to migrations: because my DataStore context class doesn't have a default constructor, I need to supply an implementation of IDbContextFactory<T> so that Code First Migrations can instantiate it:
public class MigrationDataStoreFactory : IDbContextFactory<DataStore>
{
public DataStore Create()
{
// Need to inject connection string so we can pass it to this constructor
return new DataStore(0, "CONNECTION_STRING_NEEDED_HERE");
}
}
The issue is that I can't figure out how I can inject the connection string into this class. I can't create a new constructor with a connection string parameter like this:
public class MigrationDataStoreFactory : IDbContextFactory<DataStore>
{
public string _connectionString { get; set; }
public MigrationDataStoreFactory(string connectionString)
{
_connectionString = connectionString;
}
public DataStore Create()
{
return new DataStore(0, new DateTimeProvider(() => DateTime.Now), _connectionString);
}
}
If I do, I get the following exception thrown by Migrations at runtime:
[InvalidOperationException: The context factory type 'MigrationDataStoreFactory' must have a public default constructor.]
System.Data.Entity.Infrastructure.DbContextInfo.CreateActivator() +326
System.Data.Entity.Infrastructure.DbContextInfo..ctor(Type contextType, DbProviderInfo modelProviderInfo, AppConfig config, DbConnectionInfo connectionInfo) +106
System.Data.Entity.Infrastructure.DbContextInfo..ctor(Type contextType) +52
System.Data.Entity.Migrations.DbMigrator..ctor(DbMigrationsConfiguration configuration, DbContext usersContext) +202
System.Data.Entity.Migrations.DbMigrator..ctor(DbMigrationsConfiguration configuration) +66
System.Data.Entity.MigrateDatabaseToLatestVersion`2.InitializeDatabase(TContext context) +50
// Truncated stack trace, but you get the idea
Aside from that, this class is not instantiated by Unity anyway; it seems to just be called by convention by Code First Migrations somehow, so even if I could do that it wouldn't really help...
Everything works fine if I hard-code the connection string in that method, but I don't want to do that, for obvious reasons.
Can anyone help please?
For those for whom upgrading to Entity Framework 6 is viable, there's a new overload of the migration initialization that makes this much easier:
// Parameters:
// useSuppliedContext:
// If set to true the initializer is run using the connection information from the
// context that triggered initialization. Otherwise, the connection information
// will be taken from a context constructed using the default constructor or registered
// factory if applicable.
public MigrateDatabaseToLatestVersion(bool useSuppliedContext);
Using this, you can run migrations with an injected DbContext as follows:
Database.SetInitializer(new MigrateDatabaseToLatestVersion<MyDbContext, MyMigrationConfiguration>(useSuppliedContext: true));
using (var context = kernel.Get<MyDbContext>())
context.Database.Initialize(false);
Here's the approach I eventually used, using the custom IDatabaseInitializer<T> code from this answer, which helped me out a great deal.
First we add another constructor to the DataStore class (DbContext) which doesn't require the connection string parameter:
public class DataStore : DbContext, IDataStore
{
public int UserID { get; private set; }
// This is the constructor that will be called by the factory class
// if it is initialised without a connection string parameter
public DataStore(int userId)
{
UserID = userId;
}
public DataStore(int userId, string connectionString) : base(connectionString)
{
UserID = userId;
}
public virtual IDbSet<User> Users { get; set; }
// Rest of code here
}
Then we do the same for the factory class:
public class DataStoreFactory : Disposable, IDataStoreFactory
{
private DataStore _database;
private int _userId;
private string _connectionString;
// This is the constructor that will be called by the
// MigrationDataStoreFactory class
public DataStoreFactory(int userId)
{
_userId = userId;
}
public DataStoreFactory(int userId, string connectionString)
{
_userId = userId;
_connectionString = connectionString;
}
public IDataStore Get()
{
// If we have a connection string, construct our context with it,
// if not, use the new constructor
if(_connectionString != null)
_database = new DataStore(_userId, _dateTimeServices, _connectionString);
else
_database = new DataStore(_userId, _dateTimeServices);
return _database;
}
protected override void DisposeCore()
{
if (_database != null) _database.Dispose();
}
}
This is the custom initializer code:
public class MigrateDatabaseToLatestVersionWithConnectionString<TContext, TMigrationsConfiguration> : IDatabaseInitializer<TContext>
where TContext : DbContext
where TMigrationsConfiguration : DbMigrationsConfiguration<TContext>, new()
{
private readonly DbMigrationsConfiguration _config;
public MigrateDatabaseToLatestVersionWithConnectionString()
{
_config = new TMigrationsConfiguration();
}
public MigrateDatabaseToLatestVersionWithConnectionString(string connectionString)
{
// Set the TargetDatabase for migrations to use the supplied connection string
_config = new TMigrationsConfiguration {
TargetDatabase = new DbConnectionInfo(connectionString,
"System.Data.SqlClient")
};
}
public void InitializeDatabase(TContext context)
{
// Update the migrator with the config containing the right connection string
DbMigrator dbMigrator = new DbMigrator(_config);
dbMigrator.Update();
}
}
Our custom context factory (which is only ever called by Code First Migrations) can now carry on using the DataStore constructor which doesn't require a connection string:
public class MigrationDataStoreFactory : IDbContextFactory<DataStore>
{
public DataStore Create()
{
return new DataStore(0);
}
}
As long as we set the database initializer to our custom initializer and pass in the connection string (which in my case is done in Global.asax), migrations will use the correct connection:
Database.SetInitializer<DataStore>(new MigrateDatabaseToLatestVersionWithConnectionString<DataStore, MyMigrationsConfiguration>(INJECTED_CONNECTION_STRING_HERE));
Hope all that makes sense—feel free to ask for clarification in the comments.
First define your database settings interface for example IDBConnectionSettings.
In the app.config add the connection string:
<connectionStrings>
<add name=" ConnectionString "
connectionString="Integrated Security=SSPI; Persist Security Info=False; InitialCatalog=DB; Data Source=(local);"
providerName="System.Data.SqlClient" />
</connectionStrings>
To retrieve the connection string from your Settings file or your app.config you need for example to do that:
public class DBConnectionSettings()
{
get ConnectionString
{
var connections = ConfigurationManager.ConnectionStrings;
// From app.config you will get the connection string
var connectionString = connections["ConnectionString"].ConnectionString;
return connectionString;
}
}
Now you have to register the Interface somewhere in your code before using it.
unityContainer.Register<IDBConnectionSettings>();
You can use it anywhere with resolve in your case.
public class MigrationDataStoreFactory : IDbContextFactory<DataStore>
{
public string _connectionString { get; set; }
public MigrationDataStoreFactory(UnityContainer unityContainer)
{
_connectionString = unityContainer.Resolve<IDBConnectionSettings>().ConnectionString;
}
public DataStore Create()
{
return new DataStore(0, new DateTimeProvider(() => DateTime.Now), _connectionString);
}
}
Update for default constructor
Make a static method or put this code in the default constructor in this way you do not have to give any params.
var fileMap = new ExeConfigurationFileMap { ExeConfigFilename = Application.StartupPath + Path.DirectorySeparatorChar + #"app.config" }; // application name must be
using (var unityContainer = new UnityContainer())
{
var configuration = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None);
var unitySection = (UnityConfigurationSection)configuration.GetSection("unity");
unityContainer.LoadConfiguration(unitySection, "ConnectionString");
{
unityContainer.Resolve<IDBConnectionSettings>();
....
....
I hope this will solve your problem! thanks