How do you configure the DbContext when creating Migrations in Entity Framework Core?

Question

Is there way that dependency injection can be configured/bootstrapped when using Entity Framework\'s migration commands?

Entity Framework Core supports dependency in

Answer 1

As @bricelam commented this functionality does not yet exist in Entity Framework 7. This missing functionality is tracked by GitHub issue aspnet/EntityFramework#639

In the mean time, the easier workaround I found was to utilize a global state rather than hassle with subclassing. Not usually my first design choice but it works well for now.

In MyDbContext:

public static bool isMigration = true;

protected override void OnConfiguring( DbContextOptionsBuilder optionsBuilder )
{
    // TODO: This is messy, but needed for migrations.
    // See https://github.com/aspnet/EntityFramework/issues/639
    if ( isMigration )
    {
        optionsBuilder.UseSqlServer( "<Your Connection String Here>" );
    }
}

In Startup.ConfigureServices().

public IServiceProvider ConfigureServices( IServiceCollection services )
{
    MyContext.isMigration = false;

    var configuration = new Configuration().AddJsonFile( "config.json" );
    services.AddEntityFramework( configuration )
        .AddSqlServer()
        .AddDbContext<MyDbContext>( config => config.UseSqlServer() );
    // ...
}

(The configuration code actually lives in an Autofac Module in my case.)

Answer 2

I know this is a old question but I use the onConfiguring method and I don't have this problem

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
    optionsBuilder.UseSqlServer(Startup.Configuration.Get("Data:DefaultConnection:ConnectionString"));
}

Answer 3

I just ask for an instance and run migrations in my Startup.cs file

  public void ConfigureServices(IServiceCollection services)
    {
        // ASPNet Core Identity
        services.AddDbContext<RRIdentityDbContext>(options => options.UseSqlServer(Configuration.GetConnectionString("RRIdentityConnectionString")));

     }

And then in Configure:

   public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
        var rrIdentityContext = app.ApplicationServices.GetService<RRIdentityDbContext>();
        rrIdentityContext.Database.Migrate();
    }

Note: There is no 'EnsureCreated' for the database. Migrate is supposed to create it if it doesn't exist, although how it is supposed to figure out the permissions I don't know - so I created an empty database.

Answer 4

In .NET Core since version 2.1 should be used IDesignTimeDbContextFactory because IDbContextFactory is obsolete.

public class FooDbContextFactory : IDesignTimeDbContextFactory<FooDbContext>
{
    public FooDbContext CreateDbContext(string[] args)
    {
        IConfigurationRoot configuration = new ConfigurationBuilder()
            .SetBasePath(Directory.GetCurrentDirectory())
            .AddJsonFile("appsettings.json")
            .Build();

        var builder = new DbContextOptionsBuilder<FooDbContext>();
        var connectionString = configuration.GetConnectionString("ConnectionStringName");
        builder.UseSqlServer(connectionString);

        return new FooDbContext(builder.Options);
    }
}

Answer 5

If you are looking for a solution to configure cotext for imgrations, you can use this in you DBContext class:

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        if (!optionsBuilder.IsConfigured)
        {
            IConfigurationRoot configuration = new ConfigurationBuilder()
                .SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile("appsettings.json")
                .Build();
            var connectionString = configuration.GetConnectionString("DbCoreConnectionString");
            optionsBuilder.UseSqlServer(connectionString);
        }
    }

Remember to install those two packages to have SetBasePath and AddJsonFile methods: Microsoft.Extensions.Configuration.FileExtensions

Microsoft.Extensions.Configuration.Json

Answer 6

To combine the answers above this works for me

private readonly bool isMigration = false;
public MyContext()
{
    isMigration = true;
}

public MyContext(DbContextOptions<MyContext> options) : base(options)
{

}

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
    if (isMigration)
    {
        optionsBuilder.UseSqlServer("CONNECTION_STRING");
    }
}