Golang Decoding/Unmarshaling invalid unicode in JSON

Question

I am fetching JSON files in go that are not formatted homogeneously. For Example, I can have the following:

{"email": "\"[email protected]\""}
{"email": "[email protected]"}
{"name": "m\303\203ead"}

We can see that there will be a problem with the escaping character. Using json.Decode:

With:

{"name": "m\303\203ead"}

I get the error: invalid character '3' in string escape code

I have tried several approaches to normalise my data for example by passing by a string array (it works but there is too many edge cases), or even to filter escape characters.

Finally, I came through this article: (http://blog.golang.org/normalization) And the solution they proposed seemed very interesting.

I have tried the following

isMn := func(r rune) bool {
    return unicode.Is(unicode.Mn, r)
}

t := transform.Chain(norm.NFC, transform.RemoveFunc(isMn), norm.NFD)

fileReader, err := bucket.GetReader(filename)

transformReader := transform.NewReader(fileReader, t)

decoder := json.NewDecoder(tReader)

for {
    var dataModel Model
    if err := decoder.Decode(&kmData); err == io.EOF {
        break
    } else {
      // DO SOMETHING
    }
}

With Model being:

type Model struct {
    Name  string `json:"name" bson:"name"`
    Email string `json:"email" bson:"email"` 
}

I have tried several variations of it, but haven't been able to have it working.

So my question is how to easily handle decoding/unmarshaling JSON data with different encodings? Knowing, that I have no control on those JSON files.

If you are reading this, thank you anyway.

Answer 1

You can use json.RawMessage instead of string, that way json.Decode won't try to decode the invalid characters.

playground : http://play.golang.org/p/fB-38KGAO0

type Model struct {
    N  json.RawMessage `json:"name" bson:"name"`
}

func (m *Model) Name() string {
    return string(m.N)
}
func main() {
    s := "{\"name\": \"m\303\203ead\"}"
    r := strings.NewReader(s)
    d := json.NewDecoder(r)
    m := Model{}

    fmt.Println(d.Decode(&m))
    fmt.Println(m.Name())
}

Edit: Well, you can use regex, not sure how viable that is for you http://play.golang.org/p/VYJKTKmiYm:

func cleanUp(s string) string {
    re := regexp.MustCompile(`\b(\\\d\d\d)`)
    return re.ReplaceAllStringFunc(s, func(s string) string {
        return `\u0` + s[1:]
    })
}
func main() {
    s := "{\"name\": \"m\303\203ead\"}"
    s = cleanUp(s)
    r := strings.NewReader(s)
    d := json.NewDecoder(r)
    m := Model{}
    fmt.Println(d.Decode(&m))
    fmt.Println(m.Name())
}