Scaffolding Migrations programmatically in Asp.Net Core 5 and EF Core 5

[oNoobMastero]

I'm trying to scaffold migration files by Internal EF Core APIs programmatically. But I get:

System.NullReferenceException: 'Object reference not set to an instance of an object.'

from ScaffoldMigration method and nothing is NULL as u can see below.

and what's alternative for this
new Microsoft.EntityFrameworkCore.SqlServer.Design.Internal.SqlServerDesignTimeServices().ConfigureDesignTimeServices(designTimeServiceCollection);

because in below screenshot shows a green underline and says

It may be changed or removed without notice in any release

thanx for helping :)

EF Core version: 5.0
Database provider: Microsoft.EntityFrameworkCore.SqlServer
Target framework: ASP.NET Core 5.0
Operating system: Windows 10
IDE: Visual Studio 2019 Preview latest

[bricelam]

Remove the AddSingleton calls for MigraitonsScaffolder and its dependencies.

Here's the non-Internal way to access SqlServerDesignTimeServices:

var providerAssembly = Assembly.Load("Microsoft.EntityFrameworkCore.SqlServer");
var providerServicesAttribute = providerAssembly.GetCustomAttribute<DesignTimeProviderServicesAttribute>();
var providerServicesType = providerAssembly.GetType(providerServicesAttribute.TypeName);
var providerServices = (IDesignTimeServices)Activator.CreateInstance(providerServicesType);
providerServices.ConfigureDesignTimeServices(services);

If you still encounter errors after that, can you attach a runnable repro so we can debug further?

[oNoobMastero]

here is my modified code :

var providerServicesAttribute = providerAssembly.GetCustomAttribute<DesignTimeProviderServicesAttribute>();
var providerServicesType = providerAssembly.GetType(providerServicesAttribute.TypeName);
var providerServices = (IDesignTimeServices)Activator.CreateInstance(providerServicesType);
providerServices.ConfigureDesignTimeServices(designTimeServiceCollection);
var designTimeServices = designTimeServiceCollection.BuildServiceProvider();
var scaffolder = designTimeServices.GetRequiredService<MigrationsScaffolder>();

but last line when getting MigrationsScaffolder from the services gives error and says there is no MigrationsScaffolder registered because I removed the AddSingleton calls for MigrationsScaffolder .

can u show me the complete code of getting MigrationsScaffolder from DesignTimeServices or anywhere ?

Thanx :)

[bricelam]

Services are registered under their interface. Use IMigrationsScaffolder

[oNoobMastero]

how can I use IMigrationsScaffolder ? I mean how to get it or initiate this interface ?
I Searched everywhere but could not find a documentation on that.

Thanx :)

[bricelam]

Here's the code listing from our docs: (Note, you don't need SqlServerDesignTimeServices for Migrations)

var db = new MyDbContext();

// Create design-time services
var serviceCollection = new ServiceCollection();
serviceCollection.AddEntityFrameworkDesignTimeServices();
serviceCollection.AddDbContextDesignTimeServices(db);
var serviceProvider = serviceCollection.BuildServiceProvider();

// Add a migration
var migrationsScaffolder = serviceProvider.GetService<IMigrationsScaffolder>();
var migration = migrationsScaffolder.ScaffoldMigration(migrationName, rootNamespace);
migrationsScaffolder.Save(projectDir, migration, outputDir);

[oNoobMastero]

Thank you very much.
That was what I need

Regards ;)

[oNoobMastero]

@bricelam hey man .

now i have the same Error ( System.NullReferenceException: 'Object reference not set to an instance of an object.' ) when I try to do migration when already some migration files and the snapshot is available at migration folder..

when the Migration Folder is empty all works fine but otherwise gives me the same above error..

here is my migration code:

var serviceCollection = new ServiceCollection();
serviceCollection.AddEntityFrameworkDesignTimeServices();
serviceCollection.AddDbContextDesignTimeServices(_applicationDbContext);
var serviceProvider = serviceCollection.BuildServiceProvider();

var scaffolder = serviceProvider.GetService<IMigrationsScaffolder>();
var migration = scaffolder.ScaffoldMigration("Migration_" + DateTime.Now.ToString("ddMMyy_hhmmss"), $"SoftMax.DatabaseModels.Migrations.ApplicationDb");
var projectDir = $@"..\SoftMax.DatabaseModels\Migrations\ApplicationDb\";

this line => var migration = scaffolder.ScaffoldMigration("Migration_" + DateTime.Now.ToString("ddMMyy_hhmmss"), $"SoftMax.DatabaseModels.Migrations.ApplicationDb"); gives the error.

Regards :)