Json解组因字符无效而失败

Question

Im having difficulties to unmarshal json content in golang. One of the fields in my object contains xml content and occasionally it will fail, claiming messages such as: invalid character '\x..' in string literal

I understand that this is as a result of control characters in my xml, but dont know how to handle it. I store my documents in mongoosejs and save the xml field as type String My struct Im trying to deserialize to is declared this way:

type A struct {
  Xml []byte `json:"xml"`
}

Unmarshaling is done the following way:

var xml A
err := json.Unmarshal(content, &xml)

Answer 1

Since JSON cannot contain any control characters, I found the most convenient solution to simply convert the xml data to base64, e.g:

// before sending in javascript
a.xml = new Buffer(a.xml).toString('base64')

Then, In golang side:

// Declare a new type for custom unmarshaling
type XmlB64 []byte
func (b *XmlB64) UnmarshalJSON(data []byte) error {
    if b == nil {
        return fmt.Errorf("UnmarshalJSON on nil pointer")
    }

    if len(data) == 0 {
        return nil
    }

    if x, err := base64.StdEncoding.DecodeString(string(data)); err != nil {
        return err
    } else {
        *b = x
    }

    return nil
}

After doing that, Unmarshalling base64 content is done without doing anything special in the code. We first change our struct:

type A struct {
  Xml XmlB64 `json:"xml"`
}

Unmarshal:

var xml A
err := json.Unmarshal(content, &xml)