2017-09-06 18:20
浏览 269


In my json data structure I have a string that can have a prefix. When unmarshalling JSON, is it possible to have a function to remove that prefix? I am looking into custom JSON unmarshalling in golang and trying to leverage that.

For example. The payload can be either of the following

  "id": "urn:uuid:1234567890"

  "id": "1234567890"

When I do JSON.unmarshall(data, &struct) I'd like the unmarshall function to handle removing the urn:uuid prefix from the string if it is there so the struct will always have the value 1234567890 for id.

  • 写回答
  • 好问题 提建议
  • 关注问题
  • 收藏
  • 邀请回答

1条回答 默认 最新

  • dongxun5349 2017-09-06 19:19

    You can provide a custom UnmarshalJSON method on the data you need to trim, here is an example implementation, you may need to extend if you have to regex match the start rather than match hard string (or byte array in this case):

    go playground

    package main
    import (
    var (
        sampleJSON   = []byte(`{"id": "urn:uuid:1234567890"}`)
        prefixToTrim = []byte(`urn:uuid:`)
    type IDField string
    type Data struct {
        ID IDField `json:"id"`
    func main() {
        d := &Data{}
        err := json.Unmarshal(sampleJSON, d)
        if err != nil {
    // UnmarshalJSON provides custom unmarshalling to trim `urn:uuid:` prefix from IDField
    func (id *IDField) UnmarshalJSON(rawIDBytes []byte) error {
        // trim quotes and prefix
        trimmedID := bytes.TrimPrefix(bytes.Trim(rawIDBytes, `"`), prefixToTrim)
        // convert back to id field & assign
        *id = IDField(trimmedID)
        return nil
    解决 无用
    打赏 举报

相关推荐 更多相似问题