Enum-valued computed fields

[carlpaten]

Is your proposal related to a problem?

I would like to use computed fields to expose derived data, such as entity status (e.g. how far along is the user in a sign-up flow). With scalar computed fields, I have to use some loose type (usually text or numeric) instead of some kind of table-based enum.

Describe the solution you'd like

Example: given a user table and a user_status enum table, I'd like to be able to define CREATE FUNCTION user_status (user user) RETURNS user_status and use it in a computed column with the correct type.

Describe alternatives you've considered

• Non-computed column kept up to date with an update trigger at the SQL level: I'd rather not persist derived data. This is also unworkable if the computation is based on values in other tables.
• Postgres-level generated columns: suffers from the same limitation (can't use data from other tables).
• Use a custom scalar computed field and override the type in the generated code in codegen.yml: works if you're using graphql-codegen, and might be what we'll go for

If the feature is approved, would you be willing to submit a PR?

I'd need substantial guidance, but yes.