Non Nullable Instant receives Cannot scaffold C# literals of type 'NodaTime.Instant'.

While researching this issue I stumbled across the previously documented bug https://github.com/npgsql/efcore.pg/issues/624 which leads you to https://github.com/dotnet/efcore/issues/8741 .

• I am not scaffolding data on the object the Instant property exists on.
• When the Instant type is nullable I am able to use migrations
• When the Instant type is not nullable it produces the Cannot scaffold C# literals of type ‘NodaTime.Instant’. error
• I have a number of objects using a nullable Instant

public Instant? LastActivity { get; set; }

This produces migrations without trouble.

public Instant LastActivity { get; set; }

Produces:

System.InvalidOperationException: Cannot scaffold C# literals of type 'NodaTime.Instant'. The provider should implement CoreTypeMapping.GenerateCodeLiteral to support using it at design time.
   at Microsoft.EntityFrameworkCore.Design.Internal.CSharpHelper.UnknownLiteral(Object value)
   at Microsoft.EntityFrameworkCore.Migrations.Design.CSharpMigrationOperationGenerator.Generate(AddColumnOperation operation, IndentedStringBuilder builder)
   at System.Dynamic.UpdateDelegates.UpdateAndExecuteVoid3[T0,T1,T2](CallSite site, T0 arg0, T1 arg1, T2 arg2)
   at Microsoft.EntityFrameworkCore.Migrations.Design.CSharpMigrationOperationGenerator.Generate(String builderName, IReadOnlyList`1 operations, IndentedStringBuilder builder)
   at Microsoft.EntityFrameworkCore.Migrations.Design.CSharpMigrationsGenerator.GenerateMigration(String migrationNamespace, String migrationName, IReadOnlyList`1 upOperations, IReadOnlyList`1 downOperations)
   at Microsoft.EntityFrameworkCore.Migrations.Design.MigrationsScaffolder.ScaffoldMigration(String migrationName, String rootNamespace, String subNamespace, String language)
   at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType, String namespace)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType, String namespace)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigration.<>c__DisplayClass0_0.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)

[mrUlrik]

I moved on from this original post and instead just decided to keep them non-nullable to continue work. At some point during this I must have unknowingly corrected whatever was causing this issue. I began rewriting the original code and in the process I decided to make them nullable again and I can now create migrations without trouble. I wish I could provide more insight on my original issue.

[Bouke]

I ran into the same issue but with version 3 of EFCore. I want to create migrations for LibraryA, but run the tool in the context of ProjectA. ProjectA already had a transitive dependency on “Npgsql.EntityFrameworkCore.PostgreSQL.NodaTime” through LibraryB. LibraryA neither had a (transitive) dependency on LibraryB nor on “Npgsql.EntityFrameworkCore.PostgreSQL.NodaTime”. So the command I use is like this: ProjectA> dotnet ef migrations add --context MyDbContext --project ../LibraryA MyMigration.

Adding a direct dependency on “Npgsql.EntityFrameworkCore.PostgreSQL.NodaTime” to either ProjectA or LibraryA fixed the problem. Possibly having a transitive dependency in LibraryA would suffice, but I haven’t tested that.