NonNullable JSON data type attribute

Problem

Columns with data type Json can technically be nullable, even thought they are defined as not nullable in the prisma schema. However, it would be very helpful to mark Json columns as absolutely not nullable via a data type attribute.

This would prevent a lot of tedious logic in larger codebases which try to enforce a strict type-safety.

Example:

To please the typescript compiler that prisma queries really don’t return a null value (because we enforce that on data write/update operations) for json columns, we have a lot places which look like this:

const entity = await prisma.entity.findMany(...)

return {
      ...entity,
      entries: entity.entries.map((entry) => ({
        ...entry,
        someSubEntity: {
          ...entry.someSubEntity,
          attributes: entry.someSubEntity
            .attributes as Attributes, // we need to tell tsc that there are really no null values stored in the json column
        },
      })),
    }

Suggested solution

Introduction of a @jsonNotNullable data type attribute which ensures that both for write / update operations on the model no null value is written to the column and that the generated JsonValue type does not contain ... | null. E.g. the generated type would be something like JsonValueNotNullable = string | number | boolean | JsonObject | JsonArray

Alternatives

None.

Additional context

None.

[janpio]

Yes that is how I understood you now, you want to disallow a Json Null or Prisma.JsonNull for a specific field to further clarify what is expected and wanted in a column. The database will not be able to express that constraint (without getting fancy), but Prisma could definitely do that in the types and via validations or similar.

I think that sounds like a valid feature request if you can describe it in a way the majority of my colleagues will understand 😄

[yss14]

@aqrln Exactly! 😃