'How can I inject a service into an Entity Framework AddDbContextFactory lambda function in Blazor Server?

In Blazor server, how can I inject a scoped service into the lambda below so that I can read the authenticated user and select a SQL connection string based on the user.

builder.Services.AddDbContextFactory<GlueDbContext>((provider, options) =>
    {
        var AuthenticationStateProvider = provider.GetService<AuthenticationStateProvider>();
        // *** Compiles but FAILS because AuthenticationStateProvider is not a Singleton ***
        var user = _authenticationStateProvider.GetAuthenticationStateAsync().Result.User;
        //
        string sqlConnectString = SomeFunctionDerivingTheConnectionFromTheUser(user);
        options.UseMySql(connectionString);
    });
c++sharpentity-frameworkdependency-injectionblazorruby-on-railspdfheroku


Solution 1:[1]

Following this link, it should look something like this (I'm typing without IDE so it may contain some typos):

var serviceScopeFactory = provider.GetService<IServiceScopeFactory>(); //IServiceScopeFactory is a singleton, so you can easily get it here
using var scope = serviceScopeFactory.CreateScope();
var authenticationStateProvider = scope.GetService<AuthenticationStateProvider>();
//...

Solution 2:[2]

You can't do that. Services.Add.... simply adds classes/interfaces to a collection. It's not till later that the services container gets initialised, and until you use a DI object that an instance of that object gets initialised.

To illustrate the process, here's the code to set up a services container serviceProvider in a test.

        var services = new ServiceCollection();
        services.AddDbContextFactory<InMemoryWeatherDbContext>(options => options.UseInMemoryDatabase("WeatherDatabase"));
        services.AddSingleton<IDataBroker, ServerDataBroker>();
        var serviceProvider = services.BuildServiceProvider();

Whatever you design, it needs rethinking. You can't get a user until an SPA session has initialized.

Solution 3:[3]

AddDbContextFactory has a defaulted parameter set to Singleton. add ServiceLifetime.Scoped

builder.Services.AddDbContextFactory<GlueDbContext>((provider, options) =>
    {
        var AuthenticationStateProvider = provider.GetService<AuthenticationStateProvider>();
        var user = _authenticationStateProvider.GetAuthenticationStateAsync().Result.User;
        string sqlConnectString = SomeFunctionDerivingTheConnectionFromTheUser(user);
        options.UseMySql(connectionString);
    }, ServiceLifetime.Scoped);

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 KifoPL
Solution 2
Solution 3 Discovery-Support

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