没有要构造的键/值的Golang解组数组

Question

I'm trying to place a json array into a struct from Google Analytics API.

EG:

"rows": [
    [
        "female",
        "18-24",
        "1308"
    ],
    [
        "female",
        "25-34",
        "741"
    ]
]

Typically I'd have key/value so I can put json:"gender" but there are no keys to associate with, so the values that it would search for change.

The struct would be:

type Row struct {
    Gender   string `json:"gender"`
    AgeRange string `json:"blah"`
    Count    string `json:"blah"`
}

If I do len(jResp.Rows) I can see that it's grabbing all twelve rows/arrays but the fields are empty.

Answer 1

I don't think it's possible, with encoding/json to directly decode that json into a slice of structs without first implementing a UnmarshalJSON method on your Row type.

func (r *Row) UnmarshalJSON(data []byte) error {
     var s []string
     if err := json.Unmarshal(data, &s); err != nil {
          return err
     }
     if len(s) >= 3 {
         r.Gender = s[0]
         r.AgeRange = s[1]
         r.Count = s[2]
     }
     return nil
}

// make sure it's a slice of pointers to Row
type Resp struct {
    Rows []*Row `json:"rows"`
}

Edit: fixed the code a little to make it actually compile. Heres a working example https://play.golang.org/p/eqVQj65xJv.

You could also just decode the data first into a slice of strings and then loop over the result to build you struct values.

type Resp struct {
    Rows [][]string `json:"rows"`
}

type Row struct {
    Gender   string `json:"gender"`
    AgeRange string `json:"blah"`
    Count    string `json:"blah"`
}

var resp jResp
if err := json.Unmarshal(data, &resp); err != nil {
    panic(err)
}

var rows = make([]Row, len(resp.Rows))
for i, r := range resp.Rows {
    rows[i] = Row{
        Gender: r[0],
        AgeRange: r[1],
        Count: r[2],
    }
}

Edit: fixed this one as well. https://play.golang.org/p/Otb7iULSh3