Error in asp.net mvc core 2 scaffolding generated Controller

Question

I am working on an ASP.Net Core 2 MVC Application.

I am generating one controller per table for my backoffice with this command:

dotnet aspnet-codegenerator --project . controller -name MYTABLEController -m MYTABLE -dc MYDBContext

(replace MYTABLE and MYDBContext are examples).

Here is what the csharp Controller looks like:

namespace MYPROJECT.Controllers
{
    public class MYTABLEController : Controller
    {
        private readonly MYDBContext _context;

        public ContactsController(MYDBContext context)
        {
            _context = context;
        }

Has you can see it creates a constructor which accepts one parameter: the database object (entityframework).

When i call the web page, i get an error on this context because it is not initialized.

Here what i have to do to make it work:

namespace MYPROJECT.Controllers
{
    public class MYTABLEController : Controller
    {
        private readonly MYDBContext _context = new MYDBContext();

        public ContactsController()
        {

        }

So my question are:

Is there a best way to correct this problem ? I am wondering if it is really a bug or if i miss something.
Look and feel of each generated chtml view is very ugly. Are there some options to get something more sexy ?

Thanks

Muqeet Khan · Accepted Answer · 2017-11-29 22:04:50Z

1

The generated controller code seems fine. You did not mention the exact error, but, I am assuming you are getting the error because you haven't added the MYDBContext in your services container.

In your startup.cs file you need to add this MYDBContext into the services container so that your controller will get it injected properly. Example,

    services.AddDbContext<MYDBContext>(options =>
        options.UseSqlServer(Configuration["Data:DefaultConnection:ConnectionString"]));

After doing this, if you get the error as below:

System.ArgumentException: AddDbContext was called with configuration, but the context type 'MyDBContext' only declares a parameterless constructor.

then it means your scaffolded DbContext is not configured properly to be injected with the correct options parameter. Update the constructor to:

public partial class MYDBContext : DbContext
{
    public MYDBContext(DbContextOptions<MYDBContext> options)
        : base(options)
    {

    }

edited Nov 29, 2017 at 22:04

answered Nov 29, 2017 at 21:41

Muqeet Khan

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4 Comments

Bob5421 Over a year ago

I get this error now: System.ArgumentException: AddDbContext was called with configuration, but the context type 'MyDBContext' only declares a parameterless constructor.

Muqeet Khan Over a year ago

updated the answer, take a look. You probably need to update your DbContext class.

Bob5421 Over a year ago

In this case i got "InvalidOperationException: Unable to resolve service for type 'XXXX.XXXXContext' while attempting to activate 'XXXXX.ControllersXXXController'.

Bob5421 Over a year ago

sorry it's fine in fact

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