Scaffolding API endpoints is not working with primary constructors

[christiannagel]

Using Visual Studio, scaffolding API endpoints with read/write endpoints, using EF Core fails when using primary constructors using C# 12.

I've already reported this with the Visual Studio Developer Community, but I think this GitHub repo is a better place: https://developercommunity.visualstudio.com/t/NET-8:-scaffolding-API-endpoints-with-r/10505296

Versions:
.NET: 8.0.100-rc.2.23502.2
Visual Studio: 17.8.0 Preview 6.0

1. Create a new Web API, don’t select “use controllers” (using controllers probably has the same issues)
2. Add a model type using a primary constructor:

public class Book(int id, string title, string? publisher = default)
{
    public int Id { get; set; } = id;
    public string Title { get; set; } = title;
    public string? Publisher { get; set; } = publisher;
}

3. Add | New Scaffolded Item
4. Select Common, API --> API with read/write endpoints, using Entity Framework
5. Click Add
6. Select the model class Book
7. Click on the + with the Endpoints class, click Add
8. Click the + with the DbContext class, click Add
9. Click Add to finish the dialog

This results in an exception, error creating the DbContext, CS1514, expects { instead of the primary constructor.

As refactoring methods are available to use this new constructor, I expect this constructor to work with scaffolding.

See the project https://github.com/christiannagel/issues-scaffoldingapi/tree/main/PrimaryConstructor for a simple test.

Using an EF Core context with a primary constructor

When adding an EF Core context with a primary constructor, another error occurs:

10. Add a new class BooksContext with a primary constructor:

public class BooksContext(DbContextOptions<BooksContext> options) : DbContext(options)
{
    public DbSet<Book> Book => Set<Book>();
}

11. Repeat the steps 3.-7., with step 8. use the existing BooksContext class
12. Use the existing DbContext class
13. Click Add, then the error Sequence contains no elements is shown

See this project as a start with EF Core primary constructor: https://github.com/christiannagel/issues-scaffoldingapi/tree/main/PrimaryConstructor2

Again, I would expect this to work with primary constructors.