Migration from nullable jsonb column to non-nullable produces invalid migration

[TETYYS]

When migrating from nullable jsonb column to a non-nullable one, migration tries to execute following statements:

ALTER TABLE "Table" ALTER COLUMN "JsonbCol" SET NOT NULL;
ALTER TABLE "Table" ALTER COLUMN "JsonbCol" SET DEFAULT '';

This fails with error invalid input syntax for type json, as '' is not valid json.

---

Workaround:

Set default value for the column as valid json explicitly:

modelBuilder.Entity<Table>()
.Property(x => x.JsonbCol)
.HasDefaultValue("{}");

[roji]

@TETYYS thanks for filing this - yeah, it's an interesting case where the CLR default (empty string) isn't a valid value for the column type (json). There's an ongoing discussion in dotnet/efcore#21765 about this area, let's wait and see how it pans out there.

[roji]

Currently, based on dotnet/efcore#21765 (comment), the right way to deal with this is to edit the scaffolded migration and to manually replace the empty string with {}, as above. Right now this is by-design rather than a hacky workaround, though on the EF Core side we may discuss again what happens when a column is made non-nullable.

Closing this as by-design for now.