Is it possible to resolve an instance of ISettingsService from the ConfigureServices method in Startup(.cs) - webapplication?

I've implemented a SettingsService which is able to retrieve the database connectionstring from an external source (secure credentials store). Within the ConfigureServices I need an instance of the ISettingsService in order to get the connectionstring and pass it to the services.AddSqlServer<MyDbContext>(connectionstring) method.

While creating the instance (using var provider = services.BuildServiceProvider(); var settings = provider.GetService<ISettingsProvider>();) Visual Studio displays the next error:

Another developer posted a similar question on StackOverflow and the answer provides a solution in case of AddSingleton/ AddTransient. What is the correct way to apply it on the AddSqlServer call? Or could you provide another solution to avoid the warning/ error message?

CodePudding user response：

The Intellisense comment for .AddSqlServer actually says to use .AddDbContext if you need more control, and that's certainly the correct option.

If you refer to the source code here, you can see that all .AddSqlServer is actually doing is calling .AddDbContext and configuring the options accordingly. We can therefore write our own solution like this:

services.AddDbContext<DbContext>((serviceProvider, options) => {
    var settings = serviceProvider.GetService<ISettingsProvider>();
    // I don't know what methods your ISettingsProvider makes available
    // so adjust accordingly
    string connectionString = settings.GetSetting("connectionString");
    options.UseSqlServer(connectionString);
});

Of course you can make other changes to the options here, and .UseSqlServer can also take a Action<SqlServerDbContextOptionsBuilder> (options.UseSqlServer(connectionString, opts => opts.EnableRetryOnFailure()), etc.) to further configure it.