我有一個包含基于枚舉的類型的結構。我正在嘗試將其呈現為用戶友好的字符串。這是最小可行代碼：package mainimport ( "fmt" "gopkg.in/yaml.v3")type Job struct { Engine Engine `json:"Engine" yaml:"Engine"`}//go:generate stringer -type=Engine --trimprefix=Enginetype Engine intconst ( engineUnknown Engine = iota // must be first EngineDocker engineDone // must be last)func main() { j := Job{Engine: EngineDocker} fmt.Printf("%+v\n\n", j) out, _ := yaml.Marshal(j) fmt.Println(string(out))}這是生成的代碼：// Code generated by "stringer -type=Engine --trimprefix=Engine"; DO NOT EDIT.package mainimport "strconv"func _() { // An "invalid array index" compiler error signifies that the constant values have changed. // Re-run the stringer command to generate them again. var x [1]struct{} _ = x[engineUnknown-0] _ = x[EngineDocker-1] _ = x[engineDone-2]}const _Engine_name = "engineUnknownDockerengineDone"var _Engine_index = [...]uint8{0, 13, 19, 29}func (i Engine) String() string { if i < 0 || i >= Engine(len(_Engine_index)-1) { return "Engine(" + strconv.FormatInt(int64(i), 10) + ")" } return _Engine_name[_Engine_index[i]:_Engine_index[i+1]]}這是輸出：{Engine:1}Engine: 1這是我想要的輸出：{Engine:Docker}Engine: Docker我認為生成文件中的 String() 可以完成此操作。有什么辦法嗎？謝謝！
1 回答
隔江千里
TA貢獻1906條經驗 獲得超10個贊
yaml封送拆收器不使用String方法。相反，YAML使用 encoding.TextMarshaler和encoding.TextUnmarshaler接口。實際上，所有其他編解碼器方案——JSON、XML、TOML 等——都使用這些接口來讀取/寫入值。因此，如果您為您的類型實現這些方法，您將免費獲得所有其他編解碼器。
這是一個如何為您的枚舉制作人類可讀編碼的示例：https://go.dev/play/p/pEcBmAM-oZJ
type Engine int
const (
engineUnknown Engine = iota // must be first
EngineDocker
engineDone // must be last
)
var engineNames []string
var engineNameToValue map[string]Engine
func init() {
engineNames = []string{"Unknown", "Docker"}
engineNameToValue = make(map[string]Engine)
for i, name := range engineNames {
engineNameToValue[strings.ToLower(name)] = Engine(i)
}
}
func (e Engine) String() string {
if e < 0 || int(e) >= len(engineNames) {
panic(fmt.Errorf("Invalid engine code: %d", e))
}
return engineNames[e]
}
func ParseEngine(text string) (Engine, error) {
i, ok := engineNameToValue[strings.ToLower(text)]
if !ok {
return engineUnknown, fmt.Errorf("Invalid engine name: %s", text)
}
return i, nil
}
func (e Engine) MarshalText() ([]byte, error) {
return []byte(e.String()), nil
}
func (e *Engine) UnmarshalText(text []byte) (err error) {
name := string(text)
*e, err = ParseEngine(name)
return
}
怎么運行的：
func main() {
j := Job{Engine: EngineDocker}
fmt.Printf("%#v\n\n", j)
out, err := yaml.Marshal(j)
if err != nil {
panic(err)
}
fmt.Printf("YAML: %s\n", string(out))
var jj Job
err = yaml.Unmarshal(out, &jj)
if err != nil {
panic(err)
}
fmt.Printf("%#v\n\n", jj)
// == JSON ==
out, err = json.Marshal(j)
if err != nil {
panic(err)
}
fmt.Printf("JSON: %s\n", string(out))
var jjs Job
err = json.Unmarshal(out, &jjs)
if err != nil {
panic(err)
}
fmt.Printf("%#v\n\n", jjs)
}
輸出
main.Job{Engine:1}
YAML: Engine: Docker
main.Job{Engine:1}
JSON: {"Engine":"Docker"}
main.Job{Engine:1}
看？它無需任何額外工作即可將字符串寫入 YAML 和 JSON 并從中讀取。
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