Use DbContext in ASP .Net Singleton Injected Class

Question

I need to access my database in a Singleton class instantiated in my Startup class. It seems that injecting it directly results in a DbContext that is disposed.

I g

Answer 1

Update

I'm fully aware that this solution is not the right way to do it. Please don't do what I did here all those years ago. In fact, don't inject a singleton DbContext at all.

Old answer

The solution was to call AddSingleton with my class being instantiated in the method parameter in my Startup class:

services.AddSingleton(s => new FunClass(new MyContext(null, Configuration["Data:DefaultConnection:ConnectionString"])));

The solution was to change my DbContext class:

public class MyContext : IdentityDbContext
{
    private string connectionString;

    public MyContext()
    {
        
    }

    public MyContext(DbContextOptions options, string connectionString)
    {
        this.connectionString = connectionString;
    }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        // Used when instantiating db context outside IoC 
        if (connectionString != null)
        {
            var config = connectionString;
            optionsBuilder.UseSqlServer(config);
        }
     
        base.OnConfiguring(optionsBuilder);
    }

}

As multiple people have however warned, using a DbContext in a singleton class might be a very bad idea. My usage is very limited in the real code (not the example FunClass), but I think if you are doing this it would be better to find other ways.