Get Multiple Connection Strings in appsettings.json without EF

Question

Just starting playing with the .Net Core RC2 by migrating a current MVC .Net app I developed. It looks like to me because of the way that configuration is handled with appsettings.json that if I have multiple connection strings I either have to use EF to retrieve a connectionstring or I have to create separate classes named for each connection string. All the examples I see either use EF (which doesn't make sense for me since I will be using Dapper) or the example builds a class named after the section in the config. Am I missing a better solution?

    "Data": {
        "Server1": {
          "ConnectionString": "data source={server1};initial catalog=master;integrated security=True;"
        },
        "Server2": {
          "ConnectionString": "data source={server2};initial catalog=master;integrated security=True;"
        }
    }

Why would I want to build two classes, one named "Server1" and another "Server2" if the only property each had was a connectionstring?

You don't need to build any classes. You just access the settings like this: `Configuration["Data:Server1:ConnectionString"]` — Pawel, May 17 '16 at 22:53
@Pawal that should be an answer IMO. Also: I learned something, thanks. I haven't had time to play with those bits yet - much obliged. — Marc Gravell, May 17 '16 at 23:04
@Pawal I should have included that as an example as well. The issue I'm having with that is that Configuration is only accessible in the Startup.cs. I'm not sure what method on the IServiceCollection to add it to in order to get that string into my DAL. Make sense? And thank you for your help — Couch, May 17 '16 at 23:58

score 7 · Answer 1 · answered May 20 '16 at 14:17

There are a couple of corrections that I made to Adem's response to work with RC2, so I figured I better post them.

I configured the appsettings.json and created a class like Adem's

{
    "ConnectionStrings": {
      "DefaultConnectionString": "Default",
      "CustomConnectionString": "Custom"
    }
}

and

public class ConnectionStrings
{
    public string DefaultConnectionString { get; set; }

    public string CustomConnectionString { get; set; }
}

most of Adem's code comes out of the box in VS for RC2, so I just added the line below to the ConfigureServices method

services.Configure<Models.ConnectionStrings>(Configuration.GetSection("ConnectionStrings"));

The main missing point is that the connection string has to be passed to the controller (Once you’ve specified a strongly-typed configuration object and added it to the services collection, you can request it from any Controller or Action method by requesting an instance of IOptions, https://docs.asp.net/en/latest/mvc/controllers/dependency-injection.html)

So this goes to the controller,

private readonly ConnectionStrings _connectionStrings;
        public HomeController(IOptions<ConnectionStrings> connectionStrings)
        {
            _connectionStrings = connectionStrings.Value;
        }

and then when you instantiate the DAL you pass the appropriate connectionString

DAL.DataMethods dm = new DAL.DataMethods(_connectionStrings.CustomConnectionString);

All the examples show this, they just don't state it, why my attempts to pull directly from the DAL didn't work

score 2 · Answer 2 · edited Jul 24 '20 at 14:55

I don't like the idea of instantiating the DAL. Rather, I'd do something like this

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

And something like this in the ctor of the DAL

public Dal(IOptionsMonitor<ConnectionStrings> optionsAccessor, ILogger<Dal> logger)
{
      _connections = optionsAccessor.CurrentValue;
      _logger = logger;
}

and you'll need to register with IoC

    services.Configure<ConnectionStrings>(configuration.GetSection("ConnectionStrings")); /* services is the IServiceCollection */

Now you have all the connection strings in the DAL object. You can use them on each query or even select it by index on every call.

I added code for the missing IoC registrations. But a simple way to get access, thanks. — granadaCoder, Jul 24 '20 at 14:55

adem caglin · Answer 3 · 2016-05-18T08:34:57.430

You can use Options to access in DAL layer. I will try to write simple example(RC1):

First you need to create appsettings.json file with below content:

{
    "ConnectionStrings": {
      "DefaultConnectionString": "Default",
      "CustomConnectionString": "Custom"
    }
}

Then create a class:

public class ConnectionStrings
{
    public string DefaultConnectionString { get; set; }

    public string CustomConnectionString { get; set; }
}

And in Startup.cs

    private IConfiguration Configuration;
    public Startup(IApplicationEnvironment app)
    {
        var builder = new ConfigurationBuilder()
           .SetBasePath(app.ApplicationBasePath)
           .AddJsonFile("appsettings.json");

        Configuration = builder.Build();
    }
    public void ConfigureServices(IServiceCollection services)
    {
        // ....
        services.AddOptions();
        services.Configure<ConnectionStrings>(Configuration.GetSection("ConnectionStrings"));
    }

Finally inject it in the DAL class:

    private IOptions<ConnectionStrings> _connectionStrings;
    public DalClass(IOptions<ConnectionStrings> connectionStrings)
    {
        _connectionStrings = connectionStrings;
    }
    //use it

In order to get this to work for "off-the-shelf" RC2 you need to get the Microsoft.Extensions.Options.ConfigurationExtensions package off the NuGet. See (https://github.com/aspnet/Home/issues/1193) — Couch, May 18 '16 at 14:58

Get Multiple Connection Strings in appsettings.json without EF

3 Answers3

Linked