具有依赖项注入的单独类库项目中的dbContext

Question

I'm currently creating a WebAPI for a school project. Before is worked with DI but i can't seem to get it working in the current context.

for the project i'm using multiple projects for the layer where my DAL needs to get the dbContext through DI.

DbContext:

public FICTIEContext(DbContextOptions<FICTIEContext> options)
        : base(options)
    {
    }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        if (!optionsBuilder.IsConfigured)
        {
        }
    }

startup register:

      public void ConfigureServices(IServiceCollection services)
    {
       services.AddDbContext<FICTIEContext>(options => options.UseSqlServer(Configuration.GetConnectionString("Database")));
    }

Call to the DAL Constructor:

public class LoginBL
{
    private LoginDAL _LoginDAL;

    public bool LoginValidation(string login, string password)
    {
        _LoginDAL = new LoginDAL(); //Gives the error. As i remember given that dependency injection works correctly it should work like this.           
        return _LoginDAL.LoginValidation(login, password); ;
    }
}

for my DAL i'm using ac# class library project with a class where i have a constructor which has the DbContext as parameter:

       private readonly FICTIEContext _Database;

    public LoginDAL(FICTIEContext database)
    {
        _Database = database;
    }

When using this code i can't seem to call the constructor without getting errors about not giving any parameters with the call to the DAL.

Which part am i missing withing my solution and how can i fix it.

Answer 1

Of course you need to provide an instance of FICTIEContext when creating an instance of a LoginDAL given your current implementation. That's the purpose of using dependency injection.

The question is whether you actually need or want dependency injection in this case? I doubt it. There should be no point of using nor testing the DAL class without a DbContext anyway.

In this case you could simply let the DAL class create an instance of the FICTIEContext internally. You may of course also provide an overload of the constructor that accepts a context if you want to:

private readonly FICTIEContext _Database;

public LoginDAL()
{
    _Database = new FICTIEContext();
}

public LoginDAL(FICTIEContext database)
{
    _Database = database;
}

Then the consumer of the class can choose whether to supply a custom FICTIEContext or let the LoginDAL class create a default one.