I am trying to unmarshal JSON of the following format:
{
"fixedString": {
"uselessStuff": {},
"alsoUseless": {},
"dynamicField": [
{ "name": "jack" }
],
"dynamicToo": [
{ "name": "jill" }
]
}
}
I would like to drop the fields "uselessStuff" and "alsoUseless", and get everything else. The other keys are user-defined and can take any value.
I can remove the fields I don't want using a custom UnmarshalJSON
(based on this answer), but I have a feeling that this is unnecessarily complicated:
package main
import (
"encoding/json"
"fmt"
)
type Response struct {
Things map[string]interface{} `json:"fixedString"`
}
type _R Response
func (f *Response) UnmarshalJSON(bs []byte) (err error) {
foo := _R{}
if err = json.Unmarshal(bs, &foo); err == nil {
*f = Response(foo)
}
delete(f.Things, "uselessStuff")
delete(f.Things, "alsoUseless")
return err
}
func main() {
j := []byte(`{ "fixedString": { "uselessStuff": {}, "alsoUseless": {}, "dynamicField": [ { "name": "jack" } ], "dynamicToo": [ { "name": "jill" } ] } }`)
var r Response
err := json.Unmarshal(j, &r)
if err != nil {
panic(err.Error())
}
for x, y := range r.Things {
fmt.Println(x, y)
}
}
Is there a way to ignore those two keys using annotations, rather than deleting them in a custom UnmarshalJSON
function (and having to add the extra type alias _R
to avoid a stack overflow)?