英文:
Unmarshaling string encoded json ints with nulls uses previous value when null
问题
我正在尝试解析包含以字符串编码的整数的 JSON 数据。使用标签来指定字段以字符串编码的方式是有效的，但是当字段为 null 时，我遇到了问题。主要问题似乎是 null 值没有被编码为字符串，因此解析器会忽略它并继续解析。问题在于它以某种原因将先前解码的值混入其中。
你有什么想法，我如何正确解析这个问题？
以下是我的代码：
package mainimport ("encoding/json""log")type Product struct {Price int `json:",string,omitempty"`}func main() {data := `[{"price": "1"},{"price": null},{"price": "2"}]`var products []Productif err := json.Unmarshal([]byte(data), &products); err != nil {log.Printf("%#v", err)}log.Printf("%#v", products)}
输出结果：
[]main.Product{main.Product{Price:1}, main.Product{Price:1}, main.Product{Price:2}}
英文:
I am trying to unmarshal json that contains ints encoded as strings. Using tags to specify that the field is encoded as a string works, but I am running into issues when the field is null. The main problem, it seems, is that the null is not encoded as a string so the parser ignores it and keeps going. The problem is that it jams in the previously decoded value for some reason.
Any ideas on how I can get this parsing correctly?
I have the following code:
package mainimport ("encoding/json""log")type Product struct {Price int `json:",string,omitempty"`}func main() {data := `[{"price": "1"},{"price": null},{"price": "2"}]`var products []Productif err := json.Unmarshal([]byte(data), &products); err != nil {log.Printf("%#v", err)}log.Printf("%#v", products)}
Output:
[]main.Product{main.Product{Price:1}, main.Product{Price:1}, main.Product{Price:2}}
答案1
得分: 2
感觉像是json包中的一个错误。
你可以通过自定义的解码器来解决这个问题，像这样，尽管如果你有一个复杂的结构体可能会有些麻烦：
func (p *Product) UnmarshalJSON(b []byte) error {m := map[string]string{}err := json.Unmarshal(b, &m)if err != nil {return err}if priceStr, ok := m["price"]; ok {p.Price, _ = strconv.Atoi(priceStr)}return nil}
http://play.golang.org/p/UKjfVqHCGi
英文:
Feels like a bug in the json package.
You can work around it with a custom Unmarshaller, like this, although it may be annoying if you've got a complex struct:
func (p *Product) UnmarshalJSON(b []byte) error {m := map[string]string{}err := json.Unmarshal(b, &m)if err != nil {return err}if priceStr, ok := m["price"]; ok {p.Price, _ = strconv.Atoi(priceStr)}return nil}
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