[Solution included] Unable to add the EntityFramework Core migration

[NickMaev]

Describe the bug

When I tried to add initial Entity Framework Core migration it couldn't create the database context.

To Reproduce

Steps to reproduce the behaviour:

1. Create a solution with name Test.
2. Create the web application project in the solution with name WebApp from the latest dev branch using the following commands:

   dotnet new -i "OrchardCore.ProjectTemplates::1.0.0-rc2-*" --nuget-source https://nuget.cloudsmith.io/orchardcore/preview/v3/index.json

   dotnet new occms

3. Create the .NET Core 5 library with name Core;
4. Add EntityFramework Core packages to both projects.
5. Create the EF Core database context ApplicationDbContext in the Core project and one entity type.
6. Try to create the initial migration. Run the following command in the solution's directory:

   dotnet ef migrations add Initial -c ApplicationDbContext -s .\WebApp -v -p .\Core

7. Get the error:

   Unable to create an object of type 'ApplicationDbContext'. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728

Expected behavior

Migration will be created successfully.

Screenshots

Solution

The problem was in the Program.cs. I renamed the BuildHost static method to CreateHostBuilder and changed the return type to IHostBuilder.

Before: Program.cs

    public class Program
    {
        public static Task Main(string[] args)
            => BuildHost(args).RunAsync();

        public static IHost BuildHost(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureLogging(logging => logging.ClearProviders())
                .ConfigureWebHostDefaults(webBuilder => webBuilder
                    .UseStartup<Startup>()
                    .UseNLogWeb())
                .Build()
            ;
    }

After: Program.cs

    public class Program
    {
        public static Task Main(string[] args)
            => CreateHostBuilder(args).Build().RunAsync();

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

[ns8482e]

Have you tried with latest dev templates? I guess rc2 templates are based on .net core 3.1 and not .net 5

[NickMaev]

Have you tried with latest dev templates? I guess rc2 templates are based on .net core 3.1 and not .net 5

It seems that the dev branch contains old templates:

https://github.com/OrchardCMS/OrchardCore/blob/dev/src/OrchardCore.Cms.Web/Program.cs

[ns8482e]

Looks like templates needs update for EF as is looking for CreateHostBuilder method

[ns8482e]

The other solution that i am using in my 3.1 project is to create design time factory as below.

public class ApplicationDbContextFactory : IDesignTimeDbContextFactory<ApplicationDbContext>
    {
        public ApplicationDbContext CreateDbContext(string[] args)
        {
            var optionsBuilder = new DbContextOptionsBuilder<ApplicationDbContext>();
            optionsBuilder.UseSqlServer("******");

            return new ApplicationDbContext(optionsBuilder.Options);
        }
    }

[NickMaev]

The other solution that i am using in my 3.1 project is to create design time factory as below.

public class ApplicationDbContextFactory : IDesignTimeDbContextFactory<ApplicationDbContext>
    {
        public ApplicationDbContext CreateDbContext(string[] args)
        {
            var optionsBuilder = new DbContextOptionsBuilder<ApplicationDbContext>();
            optionsBuilder.UseSqlServer("******");

            return new ApplicationDbContext(optionsBuilder.Options);
        }
    }

Custom "Design time factory" has a lot of disadvantages such as:

• you can't resolve DI there;
• you can't access the environment variables, services, configurations of your startup assembly;
• workarounds to fix the sharing of configurations with startup assembly looks like dirty hacks;
• you should hardcode the connection strings or passing it via arguments;
• etc.

[ns8482e]

Agree, this only helps you if you are not using DI to configure your Context options

[NickMaev]

Agree, this only helps you if you are not using DI to configure your Context options

... and you can't share your connection string from the appsettings.json or appsettings.[env].json

[ns8482e]

For my specific use case, for connection strings, I use command line with arguments and manage my uid/pwd in secret manager.

[deanmarcussen]

Is the solution here to update the templates to use CreateHostBuilder ?

[ns8482e]

@deanmarcussen Sure! template can be updated for EF

Btw, It's unrelated to OrchardCore CMS's connection string as OC's connection string is stored per Tenant under App_Data

[NickMaev]

@deanmarcussen Sure! template can be updated for EF

Btw, It's unrelated to OrchardCore CMS's connection string as OC's connection string is stored per Tenant under App_Data

It would be great to add some examples how to init the EC Core for tenants in the right way. 😉

[ns8482e]

@NickMaev OC is not using EF. Also each tenant can have it's own yessql.db

[NickMaev]

@NickMaev OC is not using EF. Also each tenant can have it's own yessql.db

I know it. But EF Core is the most popular ORM.

[Skrypt]

Dapper is quite popular too and you can use it with YesSQL.

[ns8482e]

@Skrypt @deanmarcussen I guess we can update the template to have CreateHostBuilder to align with latest ASP.NET Web application template.

@NickMaev this will help EF to read connection string from appsettings, However be aware that the change you are proposing is not related to OC's database connection string and EF will not connect to any tenant specific yessql.db as OC's connection string is stored under App_Data