How to unmarshal with different types of the same variable

Question

Im working with the API with possibile output:

[
 {
  "contactId": 2,
  "email": "karina.plain@example.com",
  "markerName": "JavascriptEngine",
  "dataType": "String",
  "value": "Carakan",
  "dateEntered": "2013-01-03T14:52:00"
 },
{
  "contactId": 2,
  "email": "karina.plain@example.com",
  "markerName": "HasReadEntireMessage",
  "dataType": "Boolean",
  "value": true,
  "dateEntered": "2013-01-03T18:02:00"
 }]

I have a problem with "value. "What should a struct look like, that will allow this JSON to be unmarshal to its array?

You could make the `Value` field have a type of `interface{}`. — mkopriva, Mar 17 '19 at 21:01

score 2 · Answer 1 · answered Mar 18 '19 at 06:42

Since it seems possible for the value of the "value" key to be of any type, you should use the type interface{} for this field. This is the empty interface, which matches any type that implements at least zero methods, which is any type.

So you can use the type:

type Contact struct {
    ContactId   int         `json:"contactId"`
    Email       string      `json:"email"`
    MarkerName  string      `json:"markerName"`
    DataType    string      `json:"dataType"`
    Value       interface{} `json:"value"`
    DateEntered string      `json:"dateEntered"`
}

See this working example.

score -1 · Answer 2 · answered Mar 17 '19 at 21:46

type Template []struct {
    ContactID   int    `json:"contactId"`
    Email       string `json:"email"`
    MarkerName  string `json:"markerName"`
    DataType    string `json:"dataType"`
    Value       string `json:"value"`
    DateEntered string `json:"dateEntered"`
}

Or

type Template []struct {
    ContactID   int    `json:"contactId"`
    Email       string `json:"email"`
    MarkerName  string `json:"markerName"`
    DataType    string `json:"dataType"`
    Value       bool   `json:"value"`
    DateEntered string `json:"dateEntered"`
}

How to unmarshal with different types of the same variable

2 Answers2