CODEWITHSUNDEEP
c#wpfentity-frameworksqliteasp.net-core
CMorgan
CMorgan

Reputation: 693

Unable to create an object of type 'DbContext' for Net Core 3.1 WPF app

My migration for my SqLite database is throwing an error:

Microsoft.EntityFrameworkCore.Design.OperationException: Unable to create an object of type 'ProductDbContext'.

---> System.MissingMethodException: No parameterless constructor defined for type 'WpfApp1.Data.ProductDbContext'.

Here is my DbContext

public class ProductDbContext : DbContext
{
    #region Constructor
    public ProductDbContext(DbContextOptions<ProductDbContext> options) : base(options)
    {
        Database.EnsureCreated();
    }

    #endregion
    #region Public properties
    public DbSet<Product> Products { get; set; }
    public DbSet<Category> Types { get; set; }
    #endregion
    #region Overridden methods
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.ApplyConfiguration(new ProductDbConfig());
        modelBuilder.ApplyConfiguration(new CategoryDbConfig());
        modelBuilder.Entity<Product>().HasData(GetProducts());
        base.OnModelCreating(modelBuilder);
    }

    private Product[] GetProducts()
    {
        // create seed data
    }
}

I have an App.xaml.cs where I do my configuration

public partial class App : Application
{
    #region Private members
    private readonly ServiceProvider serviceProvider;
    #endregion

    #region Constructor
    public App()
    {
        ServiceCollection services = new ServiceCollection();

        services.AddDbContext<ProductDbContext>(options =>
        {
            options.UseSqlite("Data Source = Product.db");
        });

        services.AddSingleton<MainWindow>();
        serviceProvider = services.BuildServiceProvider();
    }
    #endregion


    #region Event Handlers
    private void OnStartup(object s, StartupEventArgs e)
    {
        var mainWindow = serviceProvider.GetService<MainWindow>();
        mainWindow.Show();
    }
    #endregion
}

I tried adding a parameterless constructor in my dbContext. Didn't work. What is that causes this error? And how to solve this? Any help is appreciated!

Upvotes: 0

Views: 447

Answers (1)

Paul Sinnema
Paul Sinnema

Reputation: 2792

In my Xamarin.Forms application I use it this way inside the DbContext class

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        // Specify that we will use sqlite and the path of the database here
        var options = optionsBuilder
            .UseSqlite($"Data Source={SQLiteDatabasePath}");

        base.OnConfiguring(options);
    }

== EDIT ==

Singleton construction in my base class for all services:

        private static ETabberDb _DbContext;

        protected ETabberDb ETabberDbContext
        {
            get
            {
                if (_DbContext == null)
                {
                    var dbPath = DeviceService.GetSQLiteDatabasePath();

                    if (!File.Exists(dbPath))
                    {
                        File.Create(dbPath).Dispose();
                        new SQLite.SQLiteConnection(dbPath).Dispose();
                    }

                    ETabberDb.SQLiteDatabasePath = dbPath;

                    _DbContext = new ETabberDb();
                }

                return _DbContext;
            }
        }

Upvotes: 1

Related Questions