Question

I have a JSON object similar to this one:

{
  "name": "Cain",
  "parents": {
    "mother" : "Eve",
    "father" : "Adam"
  }
}

Now I want to parse “name” and “mother” into this struct:

struct {
  Name String
  Mother String `json:"???"`
}

I want to specify the JSON field name with the json:... struct tag, however I don’t know what to use as tag, because it is not the top object I am interested in. I found nothing about this in the encoding/json package docs nor in the popular blog post JSON and Go. I also tested mother, parents/mother and parents.mother.

Answer 1

Unfortunately, unlike encoding/xml, the json package doesn’t provide a way to access nested values. You’ll want to either create a separate Parents struct or assign the type to be map[string]string. For example:

type Person struct {
    Name string
    Parents map[string]string
}

You could then provide a getter for mother as so:

func (p *Person) Mother() string {
    return p.Parents["mother"]
}

This may or may not play into your current codebase and if refactoring the Mother field to a method call is not on the menu, then you may want to create a separate method for decoding and conforming to your current struct.