Override type of column

[gabegorelick]

Is there any way to override the type of a column at the Hasura level without altering the underlying DB?

My use case: I have a bigint column in Postgres that I would like to be treated as ID at the GQL layer and serialized as a string. Judging by #2881, it seems like I cannot map that bigint column to an ID GQL type. All I can do is set HASURA_GRAPHQL_STRINGIFY_NUMERIC_TYPES globally so that all bigints are serialized as strings. Or ALTER the underlying column at the DB level to be a string, but that's a very heavyweight change.

Is there any way to tell Hasura "serialize this specific column as a string"?

Other things I've tried:

• Add a computed field that casts the bigint to the correct type. This would require updating consumers to point to the new field. As far as I can tell, there's no way to mask a field with a computed one (Hasura rejects the metadata update if you try that).

[BenoitRanque]

It seems you are asking for two things:

Ability to arbitrarily map column to custom scalar type

This is not currently possible. If this feature is important to you, you may open a feature request.

Ability to arbitrarily cast a column to another type

There is no dedicated setting for this, however it can be achieved with the following workaround:

• Rename the original id column to something like _id
• Add a computed field that casts the bigint to the correct type, and name it id

I'm of course assuming your column to be mapped is named id, change this as required.

[gabegorelick]

Rename the original id column to something like _id

Just a note on this: you can't use a custom GQL field name to do this. Instead, you have to rename the column at the DB level. This is because the new computed field can't have a name that conflicts with a DB column (Hasura throws an error preventing this if you try to configure it).

[adas98012]

Thanks for the additional details. We have created a new Github issue for this. You should now be able to track the progress of this ticket.