无法为 DataContext 创建 object

Question

I am trying to run the migration in order to create sqlite DB in .net core 6. But getting the following error

Unable to create an object for DataContext.For different patterns supported at design time.

appsettings.json file code

{
  "ConnectionStrings": {
    "DefaultConnection": "Data source=UrlDB.db"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*"
}

DataContext class code

public class DataContext : DbContext
{
    public DataContext(DbContextOptions options) : base(options)
    {
    }
    public DbSet<UrlTbl> UrlTbl { get; set; }
}

I also created an extension class just to keep my code clean. and in this class, I have an extension method to addDbConext into services. Here is the code of that class

public static class ApplicationServicesExtension
{
    public static IServiceCollection AddApplicationServices(this IServiceCollection _services, IConfiguration _config)
    {
        _services.AddDbContext<DataContext>(options =>
        {
            options.UseSqlite(_config.GetConnectionString("DefaultConnection"));
        });
        return _services;
    }
}

and I am accessing this extension method in Programme.cs in this way

using UrlEntryApp.Extensions;

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();
IConfiguration _config=app.Configuration;
// Add services to the container.

builder.Services.AddControllers();
builder.Services.AddApplicationServices(_config);
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

Answer 1

Try changing your DataContext to this:

public class DataContext : DbContext
{
    protected readonly IConfiguration Configuration;

    public DataContext(IConfiguration configuration)
    {
       Configuration = configuration;
    }

    protected override void OnConfiguring(DbContextOptionsBuilder options)
    {
        // connect to sql server database
        options.UseSqlite(Configuration.GetConnectionString("DefaultConnection"));
    }
    public DbSet<UrlTbl> UrlTbl { get; set; }
}

Update your ApplicationServicesExtension to:

public static class ApplicationServicesExtension
{
    public static IServiceCollection AddApplicationServices(this IServiceCollection services)
    {
        services.AddDbContext<DataContext>();

        return services;
    }
}

In your Program.cs

...
builder.Services.AddApplicationServices();
...