Using Entity Framework Core 3.1 with Windows Application or Console Application

Question

I'm just learning Entity Framework Core 3.1. I wondering why all learning contents learn it using ASP.Net Core!! So I decide to test some of the codes on a Class Library along withConsole Application. This is my very simple class library code:

public class ApplicationDbContext : DbContext
{
    private static readonly string ConnectionString = "Server=.;Database=Northwind;Trusted_Connection=True;";
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base(options)
    {
    }

    public DbSet<NimaCategory> NimaCategories { get; set; }

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

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.ApplyConfiguration(new NimaCategoryConfig());
    }
}

I faced many strange errors for creating Migration but strangest is I must write all of these line of codes to my Console Application:

public class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Hello EF Core")
    }
    public static IHostBuilder CreateHostBuilder(string[] args)
                    => Host.CreateDefaultBuilder(args)
                        .ConfigureWebHostDefaults(
                            webBuilder => webBuilder.UseStartup<Startup>());

}
public class Startup
{
    public void ConfigureServices(IServiceCollection services)
        => services.AddDbContext<ApplicationDbContext>();
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
    }
}

and the problem is IHostBuilder and ConfigureWebHostDefaults are for ASP.Net Core and it's dependency injection engine. So based on the below link I change my csproj file:

IHostBuilder does not contain a definition for ConfigureWebHostDefaults

Now I can't run my console application because It's nature has changed and converted to Web project. Then I add a window application and I can't add these codes for configurations:

public static IHostBuilder CreateHostBuilder(string[] args)
                    => Host.CreateDefaultBuilder(args)
                        .ConfigureWebHostDefaults(
                            webBuilder => webBuilder.UseStartup<Startup>());

and:

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
        => services.AddDbContext<ApplicationDbContext>();
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
    }
}

I have some questions about this problems:

1. Why EF Core is restricted to ASP.Net Core? Are all the projects in the world written with ASP.Net Core?

2. Does anyone have experience working with EF core along with Windows Application or Console project and help to solve the issues?

Thanks

Answer 1

You can use EF Core everywhere.

Make a Console application project then install these packages

1. https://www.nuget.org/packages/Microsoft.EntityFrameworkCore.SqlServer/3.1.9

2. https://www.nuget.org/packages/Microsoft.EntityFrameworkCore.Tools/3.1.9

and put your connection string in OnConfiguringMethod.

 protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
  optionsBuilder.UseSqlServer("Server=serverName;Database=dbName;Trusted_Connection=True;MultipleActiveResultSets=True");
}

and voila you can learn ef core in console app. they just teach ef core with ASP.NET Core because of UI.

and i think Julie Lerman Teaches EF Core in Console app, you can use Pluralsight platform for EF Core tutorials.

Answer 2

Here are some answers, as well as what I use to get my EF Core working.

Why EF Core is restricted to ASP.Net Core? Are all the projects in the world written with ASP.Net Core?

It's not restricted to ASP.Net Core, EF Core and Core itself is simply a console application. And no all projects in the work are not build with ASP.NET Core --- However, due to it's flexibility Microsoft is dropping support for all other versions of .Net. Meaning the next Release of .Net will actually be .NetCore. If you are building for a normal .Net application, it might be better to use EF 6 instead of Core. Core just allows crossplatform capabilities.

Does anyone have experience working with EF core along with Windows Application or Console project and help to solve the issues?

Well yes, also all Core applications are Console Projects. So if you are able to do it in a windows application you are able to do it in Core.

---

But now I will show you what I do. I work for a company and use EF core on multiple projects, my basic formula looks like this:

Nuget Packages:

Microsoft.EntityFrameworkCore
Microsoft.EntityFrameworkCore.Design
Microsoft.EntityFrameworkCore.Relational

---

Here is the code in the Startup file. Note it will look slightly different than yours because I put my Dbcontext in a different project than my entry point.

public void ConfigureServices(IServiceCollection services)
{
    // Add the SQL db conneciton
    /*
        AddSQLContext is just a function in a different project. Not Needed
    */
    services.AddSQLContext(options => options.UseSqlServer(
    
        // This is simply the connection stirng
        Configuration.GetConnectionString("SqlConnection"),
        
        // We add a migration assembly only if the EF core DbContext is in another project
        actions => actions.MigrationsAssembly("My.Other.Project.Assembly")
    ));
                
}

---

My code for calling the Context is in another project. I like to keep it seperate. But you don't have to do that. Here are the Nuget packages I use, But I think the Tools and Design are only neccecary when doing a CodeFirst approach (building Database from EF core instead of Scaffolding):

Microsoft.EntityFrameworkCore
Microsoft.EntityFrameworkCore.Design
Microsoft.EntityFrameworkCore.SqlServer
Microsoft.EntityFrameworkCore.SqlServer.Design
Microsoft.EntityFrameworkCore.Tools

public static class ServiceCollectionExtentions
{
    /*
        SqlContext is my own custom context similar to your [ ApplicationDbContext ]
    */
    public static IServiceCollection AddSQLContext(this IServiceCollection services, Action<DbContextOptionsBuilder> options) => services
            .AddDbContext<SqlContext>(options);
            
}

---

public class SqlContext : DbContext
{
    public SqlContext(DbContextOptions options)
        : base(options){}

    
    ...
    
}

Answer 3

The solution is very simple: just add default constructor for the ApplicationDbContext:

public ApplicationDbContext()
{
}