我在Go中创建了一个API，在被调用时，执行查询，创建一个结构实例，然后在发送回调用者之前将该结构编码为JSON。现在，我想允许调用者通过传入“fields”GET参数来选择他们想要返回的特定字段。
这意味着根据字段的值，我的结构将会改变。是否有方法从结构中删除字段?或者至少动态地将它们隐藏在JSON响应中?(注:有时我有空值，所以JSON omitEmpty标签将不在这里工作)如果这些都不可能，有没有一个更好的方法来处理这个问题的建议?
下面是我正在使用的结构体的一个较小版本:
type SearchResult struct {
Date string `json:"date"`
IdCompany int `json:"idCompany"`
Company string `json:"company"`
IdIndustry interface{} `json:"idIndustry"`
Industry string `json:"industry"`
IdContinent interface{} `json:"idContinent"`
Continent string `json:"continent"`
IdCountry interface{} `json:"idCountry"`
Country string `json:"country"`
IdState interface{} `json:"idState"`
State string `json:"state"`
IdCity interface{} `json:"idCity"`
City string `json:"city"`
} //SearchResult
type SearchResults struct {
NumberResults int `json:"numberResults"`
Results []SearchResult `json:"results"`
} //type SearchResults
然后我编码并输出响应，就像这样:
err := json.NewEncoder(c.ResponseWriter).Encode(&msg)
为了扩展chhaileng的答案，这里有一个版本，删除所有出现的字段与递归
// GetJSONWithOutFields - Description: return a string representation of an interface with specified fields removed
func GetJSONWithOutFields(obj interface{}, ignoreFields ...string) (string, error) {
toJson, err := json.Marshal(obj)
if err != nil {
return "", err
}
if len(ignoreFields) == 0 {
return string(toJson), nil
}
toMap := map[string]interface{}{}
err = json.Unmarshal(toJson, &toMap)
if err != nil {
return "", err
}
for _, field := range ignoreFields {
DeleteField(toMap, field)
}
toJson, err = json.Marshal(toMap)
if err != nil {
return "", err
}
return string(toJson), nil
}
// DeleteField - Description: recursively delete field
func DeleteField(toMap map[string]interface{}, field string) {
delete(toMap, field)
for _, v := range toMap {
if m, isMap := v.(map[string]interface{}); isMap {
DeleteField(m, field)
}
}
}
使用json:“- - -”
// Field is ignored by this package.
Field int `json:"-"`
// Field appears in JSON as key "myName".
Field int `json:"myName"`
// Field appears in JSON as key "myName" and
// the field is omitted from the object if its value is empty,
// as defined above.
Field int `json:"myName,omitempty"`
// Field appears in JSON as key "Field" (the default), but
// the field is skipped if empty.
// Note the leading comma.
Field int `json:",omitempty"`
doc: http://golang.org/pkg/encoding/json/#Marshal
我创建了这个函数，通过忽略一些字段将struct转换为JSON字符串。希望能有所帮助。
func GetJSONString(obj interface{}, ignoreFields ...string) (string, error) {
toJson, err := json.Marshal(obj)
if err != nil {
return "", err
}
if len(ignoreFields) == 0 {
return string(toJson), nil
}
toMap := map[string]interface{}{}
json.Unmarshal([]byte(string(toJson)), &toMap)
for _, field := range ignoreFields {
delete(toMap, field)
}
toJson, err = json.Marshal(toMap)
if err != nil {
return "", err
}
return string(toJson), nil
}
例如:https://play.golang.org/p/nmq7MFF47Gp
为了扩展chhaileng的答案，这里有一个版本，删除所有出现的字段与递归
// GetJSONWithOutFields - Description: return a string representation of an interface with specified fields removed
func GetJSONWithOutFields(obj interface{}, ignoreFields ...string) (string, error) {
toJson, err := json.Marshal(obj)
if err != nil {
return "", err
}
if len(ignoreFields) == 0 {
return string(toJson), nil
}
toMap := map[string]interface{}{}
err = json.Unmarshal(toJson, &toMap)
if err != nil {
return "", err
}
for _, field := range ignoreFields {
DeleteField(toMap, field)
}
toJson, err = json.Marshal(toMap)
if err != nil {
return "", err
}
return string(toJson), nil
}
// DeleteField - Description: recursively delete field
func DeleteField(toMap map[string]interface{}, field string) {
delete(toMap, field)
for _, v := range toMap {
if m, isMap := v.(map[string]interface{}); isMap {
DeleteField(m, field)
}
}
}
