Pass multiple connection strings through IServicesCollection.AddScoped()

Question

.net core webapi application with entityframeworkcore. Trying to figure out how to pass an additional connection string into the data access library class in addition to the dbcontext. See ** dbcontext ** below is what I want to do.

startup.cs

       var SqlConnection = Configuration.GetConnectionString("SQLConnection");  
       var BlobConnection = Configuration.GetConnectionString("BlobConnection");

        services.AddEntityFramework()
                .AddEntityFrameworkSqlServer()
                .AddDbContext<VISTrackingContext>(options => options.UseSqlServer(SqlConnection, 
                sqlServerOptionsAction: sqlOptions =>
                {
                    sqlOptions.EnableRetryOnFailure(maxRetryCount: 5,
                    maxRetryDelay: TimeSpan.FromSeconds(5),
                    errorNumbersToAdd: null);
                }));

        services.AddScoped<IDataManager>(c => new DataManager(**_dbcontext**, BlobConnection));

        public FileController(IDataManager manager)
        {
            _datamanager = manager;
        }

        public DataManager(VISTrackingContext dbcontext, string blobconnection)
        {
            _dbcontext = dbcontext;
            _blobconnection = blobconnectionstring;
        }

Can this be done? Or is there another way to inject an additional connection string through the context object itself? I see lots of comments and options on doing this but none of the approaches deal with both the context and the connection string being passed to the repository object.

score 1 · Answer 1 · answered Jun 27 '17 at 23:55

You could store those connection strings in an object, and inject it to DataManager.

For example,

public class Startup
{
   public void ConfigureServices(IServiceCollection services)
   {
      ...
      services.AddSingleton(provider => new DataSettings(
         Configuration.GetConnectionString("SQLConnection"), 
         Configuration.GetConnectionString("BlobConnection")));

      services.AddScoped<IDataManager, DataManager>();
      ...
   }
}

public class DataSettings
{
    public DataSettings(string sqlConnection, string blobConnection)
    {
        SQLConnection = sqlConnection;
        BlobConnection = blobConnection;
    }

    public string SQLConnection { get; }

    public string BlobConnection { get; }
}

public DataManager(VISTrackingContext dbcontext, DataSettings dataSettings)
{
   _dbcontext = dbcontext;
   _blobconnection = dataSettings.BlobConnection;
}

This looks great, but, how does this work? What links the datamanager in addscoped to the AddSIngleton(... class above it? — user2503078, Jun 28 '17 at 00:04
Inversion of Control (IoC) container should automatically resolve both dependencies - `VISTrackingContext` and `DataSettings` for `DataManager` at runtime. It is a beauty of using IoC container. — Win, Jun 28 '17 at 00:16

score 0 · Answer 2 · answered Jun 28 '17 at 06:09

Alternatively to @Win's answer, a more generic approach:

public class ConnectionStrings : Dictionary<string,string> { }

Startup.cs

services.Configure<ConnectionStrings>(Configuration.GetSection("ConnectionStrings"));
service.AddScoped<IDataManager,DataManager>();

// or
services.AddScoped<IDataManager>(c => new DataManager(
    c.GetRequiredService<YourDbContext>(),
    c.GetRequiredService<ConnectionStrings>()["BlobConnection"])
);

Service

public DataManager(VISTrackingContext dbcontext, ConnectionStrings connectionStrings)

Pass multiple connection strings through IServicesCollection.AddScoped()

2 Answers2