fix(typegen): typescript: deprecate `Json` type in favour of `unknown`

[isaacharrisholt]

What kind of change does this PR introduce?

Bug fix

What is the current behavior?

#676

What is the new behavior?

Json has been marked as deprecated and is now just equivalent to unknown.

FIxes #676

[avallete]

Hi there !

Thank you for your contribution !

This looks great, and would also help when overriding the Database default Json types for a specific ones using the type-fest, MergeDeep utilities like recommended in the docs eg:

export type CustomUserDataType = {
  foo: string
  bar: {
    baz: number
  }
  en: 'ONE' | 'TWO' | 'THREE'
  record: Record<string,  string> | null
  recordNumber: Record<number, string> | null
}

export type Database = MergeDeep<
  GeneratedDatabase,
  {
    public: {
      Tables: {
        users: {
          Row: {
            data: CustomUserDataType | null
          }
          Insert: {
            data?: CustomUserDataType | null
          }
          Update: {
            data?: CustomUserDataType | null
          }
        }
      }
    }
  }
>

Such override will result in a non-clean merge object (some union will happen) if they type merged to is Json, but will work just fine with unknown.

However, I would keep this as a flagged feature change for now, similar to the detect_one_to_one_relationships option, that we can then turn-on by default.

It'll allow us to deploy the change gradually and still offer users for who it might be a breaking change to gradually opt-in and refactor when they're ready. Without breaking their types definitions.

Maybe something like json_as_unknown.

Edit:

Another thing to consider is that the postgrest-js type inference also rely on a Json type for the "json accessor typing" fonctionnality: https://github.com/supabase/postgrest-js/blob/956ed181147b3477daf81311c374c643323eab76/src/select-query-parser/types.ts#L16-L24

This will probably need to be changed as well so for consistency with this change 🤔

So this might end up being more of a breaking change than expected. The only way I can think of doing this without breaking change is by refactoring the types inference to have a dynamic "Json" type instead of a static one, but it might not be worth it though if that's not the way we want to go moving forward.