Go JSON元帅的默认案例选项？

Question

I have the following structures to export onto json:

type ExportedIncident struct {
    Title      string `json:"title"`
    Host       string `json:"host"`
    Status     string `json:"status"`
    Date       string `json:"date"`
    Notes      []ExportedNote `json:"notes"`
    LogEntries []ExportedLogEntry `json:"log_entries"`
}

And I want underscore cased fields, so I had to define each field just for that as described in this answer: https://stackoverflow.com/a/11694255/1731473

But it's really cumbersome and I believe there is a simpler solution in Go, but I can't find it.

How can I set default letter-case (underscore, snake, camel...) for JSON export?

Answer 1

Unfortunately there are no opportunities to export your fields into snake_case so you have to maintain tags by yourself.

Technically you can use method MarshalJSON and perform all manipulations inside this method, but it isn't easier way...

Answer 2

As mentioned by @Vladimir Kovpak, you can't do this with the standard library, at least at the moment.

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Though, inspired by this , you can achieve something close to what you want to do. Check out MarshalIndentSnakeCase :

func MarshalIndentSnakeCase(v interface{}, prefix, indent string) ([]byte, error) {
    b, err := json.MarshalIndent(v, prefix, indent)
    if err != nil {
        return nil, err
    }

    x := convertKeys(b) // Here convert all keys from CamelCase to snake_case

    buf := &bytes.Buffer{}
    err = json.Indent(buf, []byte(x), prefix, indent)
    if err != nil {
        return nil, err
    }

    return buf.Bytes(), nil
}

Down Sides:

• You have to do the same in the opposite direction for Unmashalling to work.
• The order of elements is lost due to using a map inside convertKeys() .

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Try it on Go Playground .