Prevent Marshal From Escaping Quotes on String Field of Struct

Question

I am having an issue parsing the following structure, where JsonData is a string of JSON stored in a database.

type User struct {
    Id          uint64  `json:"user_id"`
    JsonData    string  `json:"data"`
}

user := &User {
    Id: 444,
    JsonData: `{"field_a": 73, "field_b": "a string"}`,
}

If I json.Marshal this, it will escape the quotes but that will give me the JSON:

{
    "user_id" : 444,
    "data": "{\"field_a\": 73, \"field_b\": \"a string\"}"
}

Is there a way to tell the marshaller to avoid escaping the JsonData string and putting it in quotes, so it looks like this?

{
    "user_id" : 444,
    "data": {"field_a": 73, "field_b": "a string"}
}

I would prefer to not jump through too many hoops like creating an entirely new User-like object and/or unmarshaling/remarshaling the string etc.

Answer 1

Seems like RawMessage is what you are looking for:

RawMessage is a raw encoded JSON object. It implements Marshaler and Unmarshaler and can be used to delay JSON decoding or precompute a JSON encoding.

Playground: http://play.golang.org/p/MFNQlISy-o.