Change EF connection string when user logs in with Identity - entity-framework

Question

My question is about extending this previous post using identity to calculate the connection string for each user: ASP.NET Core change EF connection string when user logs in
I tried the following approach :
Startup.cs:
public void ConfigureServices(IServiceCollection services)
{
var c = new SqlConnectionStringBuilder
{
-- the connection string to the users repository --
};
services.AddDbContextFactory<MasterDBContext>(options =>
options.UseSqlServer(c.ConnectionString));
services.AddScoped<MasterDBContext>(p => p.GetRequiredService<IDbContextFactory<MasterDBContext>>().CreateDbContext());
services.AddDefaultIdentity<MyUser>(options =>
options.SignIn.RequireConfirmedAccount = true)
.AddEntityFrameworkStores<MasterDBContext>();
services.AddTransient<IMasterUserService, MasterUserService>();
services.AddDbContextFactory<UserDbContext>();
}
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
else
{
app.UseExceptionHandler("/Error");
app.UseHsts();
}
app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthentication();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
{
endpoints.MapDefaultControllerRoute();
endpoints.MapControllers();
endpoints.MapBlazorHub();
endpoints.MapFallbackToPage("/_Host");
});
}
UserDbContext:
public MyContext(IServiceProvider provider)
{
_provider = provider;
}
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
var haccess = (IHttpContextAccessor)_provider.GetService(typeof(IHttpContextAccessor));
var scopefactory = haccess.HttpContext.RequestServices.GetService<IServiceScopeFactory>();
using (var scope = scopefactory.CreateScope())
{
var userManager = scope.ServiceProvider.GetRequiredService<UserManager<MyUser>>();
var user = userManager.GetUserAsync(haccess.HttpContext.User).Result;
var userServ = scope.ServiceProvider.GetRequiredService<IMasterUserService>();
optionsBuilder.UseSqlServer(userServ.GetConnectionString(user).Result);
}
base.OnConfiguring(optionsBuilder);
}
But, even in a scope, no way to get access to UserManager service (usermanager injection works fine from others services and controllers). I get an "invalid operation exception" at the usermanager connection point.
What is wrong with that code ?
Thanks in advance

Answer 1

I found the solution at the end... My code in MyContext.OnConfiguring is correct if you add services.TryAddScoped<UserManager>(); in the ConfigureServices function of statup.cs.
All together, I'm able to get a connection string depending of the current user from any service :
public class MyService : IMyService
{
private IDbContextFactory _dbfactory;
public MyService(IDbContextFactory<MyContext> dbfactory)
{
_dbfactory = dbfactory;
}
public async Task AnyAsync()
{
using (var dbtf = _dbfactory.CreateDbContext())
{
... your code ...
}
}
}