Add json data type

[amit-momin]

Migrated the json data type from /core/services/pg/datatypes

[jmank88]

Do we need to call Marshall and unmarshal explicitly on rawmessage? Aren't those no-ops?

[dimriou]

I would test Jordan's comment about marshal & unmarshal methods but otherwise looks ok.

[jmank88]

I would test Jordan's comment about marshal & unmarshal methods but otherwise looks ok.

Oh the implementations are basically no-ops anyways - just support for nil->null:

// MarshalJSON returns m as the JSON encoding of m.
func (m RawMessage) MarshalJSON() ([]byte, error) {
	if m == nil {
		return []byte("null"), nil
	}
	return m, nil
}

// UnmarshalJSON sets *m to a copy of data.
func (m *RawMessage) UnmarshalJSON(data []byte) error {
	if m == nil {
		return errors.New("json.RawMessage: UnmarshalJSON on nil pointer")
	}
	*m = append((*m)[0:0], data...)
	return nil
}

https://cs.opensource.google/go/go/+/refs/tags/go1.21.4:src/encoding/json/stream.go;l=260-275

[jmank88]

I like having a separate package for json related things, but it has two problems:

• if you import std lib also, then you have to alias one of them as something other than json
• redundant naming from outside the package: json.JSON

What about something like package jsonutil? And we could reuse the name RawMessage

• jsonutil.RawMessage

Or maybe this makes sense in the sqlutil package, in which case the JSON name is probably fine.

• sqlutil.JSON

I'm thinking this feels more SQL related 🤔

Edit: is the core side change ready? That would help give some perspective.

[amit-momin]

I have this PR open but it still needs the changes to point to the JSON type here in chainlink-common. But any place I've replaced datatypes.JSON -> json.RawMessage is where I'd use this. I think naming the package jsonutil makes sense. It doesn't seem completely SQL related since it's used for things like the TxMeta type.

[jmank88]

You can temporarily use the hash from this PR to show passing tests on the core side.

[jmank88]

It doesn't seem completely SQL related since it's used for things like the TxMeta type.

The whole purpose of the type is to extend support for SQL though:

// JSON defined JSON data type, need to implements driver.Valuer, sql.Scanner interface
type JSON json.RawMessage

[amit-momin]

That's true. For the current changes, it's using these methods under the hood so I can also get behind putting this under sqlutil. But I could see someone using this type just for RawMessage without the extended support being needed. Even though RawMessage could be used directly from encoding/json, would we want to use this type here going forward for consistency?

[jmank88]

Even though RawMessage could be used directly from encoding/json, would we want to use this type here going forward for consistency?

No, I think each case should use whatever fits best. They are still compatible when defined this way, and can even be converted without any runtime cost.

[amit-momin]

Ok in that case I'll move this under the sqlutil package