Is EF Core Add Migration Supported from .NET Standard Library?

Question

We have been trying to run EF Core Migration in .Net Standard 1.6 class library, but it has been failing. But same passes very well in .Net Core 1.1 class library.

Answer 1

All that right but there is a complexity and i would like to give an explanation.

Case: Asp.Net Core, I have a standard library that containing Db-Context. I want to migrate this context but standard library doesn't accepting migration directly, needs a startup project.

Solution: startup project is able to create migration indirectly

Enable-Migrations MyMigration -Project DB-ContextProjectNameThatIsStandartLib -StartupProject CallerExecutableProjectName_LikeMVCWebProjectOrConsole

Add-Migration MyMigration -Project DB-ContextProjectNameThatIsStandartLib -StartupProject CallerExecutableProjectName_LikeMVCWebProjectOrConsole

We will choose Caller Project from the Package Manager Console DropDown but it will create the migration file in the library project. After that don't choose other project from the drop down and run update from the caller project directly without any argument.

Update-Database

try it strange but true

Update: I have upgraded my project Asp.net EntityFrameworkCore 3.1.3 to 3.1.4 and those on up hasnt worked firectly and gave an error :

The EntityFramework package is not installed on project

and this error

Unable to create an object of type 'DomainDbContext'. For the different patterns supported at design time

This is an EntityFramework.Core application! I have installed also EntityFramework to the standart library. But it couldnt understand and restarted V.S. This time it needed to install entityframework to starter MVC (Web) project. I can't do that. I decide to add a new Console Application to solving this requirement. And created below application for this

install-Package Microsoft.Extensions.Configuration
Install-Package Microsoft.Extensions.Configuration.Json
Install-Package Microsoft.Extensions.Configuration.CommandLine
Install-Package Microsoft.Extensions.Configuration.EnvironmentVariables

class Program
{
    public class DesignTimeDbContextFactory : IDesignTimeDbContextFactory
    {
        public DomainDbContext CreateDbContext(string[] args)
        {
            IConfigurationRoot configuration = new ConfigurationBuilder()
                .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
                .AddEnvironmentVariables()
                //.SetBasePath(Directory.GetCurrentDirectory())
                //.AddJsonFile("appsettings.json")
                .Build();
            var builder = new DbContextOptionsBuilder();
            var connectionString = configuration.GetConnectionString("DefaultConnection");
            builder.UseSqlServer(connectionString);
            return new DomainDbContext(builder.Options);
        }
    }

    static void Main(string[] args)
    {
        Console.WriteLine("Hello World!");
    }
}

This time it has worked correctly! with the above commands again :) cheer