如何以非手动方式更改所有struct标记的前缀？

Question

Suppose I have the following:

type My struct{
  First string `xml:"first"`
  Last string `xml:"name"`
  ...many more tags...
}

I'd like to change the prefix of all the tags to "mycustomtag". I've seen https://stackoverflow.com/a/42549826/522962 but that describes a manual way where you have defined a second struct w/ the tags manually. How do i do so automatically?

e.g. I'd like to end up with something like below but since there are many, many fields how do I do it so I don't have to do it manually?:

// how do I do the next part automagically????
func (m *My) MarshalJSON() ([]byte, error) {
    type alias struct {
        First string `mycustomtag:"first"`
        Last string `mycustomtag:"name"`
        ...many more tags...
    }
    var a alias = alias(*m)
    return json.Marshal(&a)
}

Answer 1

If this is not at runtime, but statically to modify your code source, you can use fatih/gomodifytags.

See "Writing a Go Tool to Parse and Modify Struct Tags"

Struct field tags are an important part of encode/decode types, especially when using packages such as encoding/json.
However, modifying tags is repetitive, cumbersome and open to human errors.
We can make it easy to modify tags with an automated tool that is written for this sole purpose.