Use json.RawMessage to represent `JSON` type struct fields instead of []byte

[Goldziher]

What do you want to change?

Hi there,

I'd like to ask for an update to how structs are generated. Instead of using []byte to represent a JSON type field, use json.RawMessage. This affects serialization and deserialization primarily. It could of course just be optional.

What database engines need to be changed?

PostgreSQL

What programming language backends need to be changed?

Go

[andrewmbenton]

As far as I can tell, sqlc does use json.RawMessage for PostgreSQL JSON database columns. Here's a playground link to demonstrate: https://play.sqlc.dev/p/e54dc46953ed8e3c1be0875c17b84ddb53f65825afc1f20b014d78309331f5b2

In what context are you seeing []byte?

[Goldziher]

As far as I can tell, sqlc does use json.RawMessage for PostgreSQL JSON database columns. Here's a playground link to demonstrate: https://play.sqlc.dev/p/e54dc46953ed8e3c1be0875c17b84ddb53f65825afc1f20b014d78309331f5b2

In what context are you seeing []byte?

it does not use it to represent struct fields or on receivers for me.

[andrewmbenton]

it does not use it to represent struct fields or on receivers for me.

Understood, I just can't reproduce that behavior. Can you provide an example using https://play.sqlc.dev or modify the one I linked previously?

[Goldziher]

it does not use it to represent struct fields or on receivers for me.

Understood, I just can't reproduce that behavior. Can you provide an example using https://play.sqlc.dev or modify the one I linked previously?

You are very nice! thanks.

The reproduction is simple, the issue is when using pgx.

See this: https://play.sqlc.dev/p/02d8afb0d4d5c2f12f31141833558cb6342747a6eb44f6264f2c2462d2f276b1

I updated the config to use pgx - with sqlc.json looking like this:

{
  "version": "2",
  "sql": [{
    "schema": "schema.sql",
    "queries": "query.sql",
    "engine": "postgresql",
    "gen": {
      "go": {
        "out": "db",
        "sql_package": "pgx/v5"
      }
    }
  }]
}

And added a json value to the model. The result is this:

[Goldziher]

I think this can be filed as a bug when using pgx

[andrewmbenton]

I see, thanks for updating the example. I found an older issue (#2801) which describes the difference in behavior when using different drivers. There is an override workaround described there that should work for you.

I think arguably json.RawMessage should be the default, but since it's a breaking change it will have to wait for a major release. I've added it to the list.

[Goldziher]

Much obliged!