Unmarshal nested JSON with different structure but same keys - json

Question

I'm trying to unmarshal some nested JSON which looks like:
{
"id": "aRandomId",
"type": "aRandomType",
"aRandomField": {
"type": "someType",
"createdAt": "2020-07-07T15:50:02",
"object": "anObject",
"modifiedAt": "2020-07-07T15:50:02"
},
"aParameter": {
"type": "Property",
"createdAt": "2020-07-07T15:50:02",
"value": "myValue",
"modifiedAt": "2020-07-07T15:50:02"
},
"location": {
"type": "GeoProperty",
"value": {
"type": "Point",
"coordinates": [
7.0054,
40.9999
]
}
},
... other things with type, value ...
"createdAt": "2020-07-07T15:50:02",
"modifiedAt": "2020-07-07T15:50:02",
}
I would like to get all keys and values which are: type, createdAt, Value (also if they are nested)
Actually, I have 2 structs:
type Attribute struct {
Type string `json:"type"`
CreatedAt string `json:"createdAt"`
Value string `json:"value"`
ModifiedAt string `json:"modifiedAt"`
}
type Entity struct {
Id string `json:"id"`
Type string `json:"type"`
CreatedAt string `json:"createdAt"`
Attribute Attribute
}
in := []byte(buf.String())
var entity Entity
err := json.Unmarshal(in, &entity)
if err != nil {
panic(err)
}
frame.Fields = append(frame.Fields,
data.NewField("key", nil, []string{"type : ", "createdAt : ", "name : "}),
)
frame.Fields = append(frame.Fields,
data.NewField("value", nil, []string{entity.Type, entity.CreatedAt, entity.Attribute.Value}),
)
The problem is there can be several different Attribute struct andIi can't provide them all.
I would like to display all key (only type, createdAt and Value) in one frame and all their value in another.
Maybe have something like that?
type Entity struct {
attribute List<Attribute>
}
type Attribute struct{
Type string
CreatedAt string
Value string
ModifiedAt string
}

Answer 1

The problem is there can be several different Attribute struct andIi can't provide them all
It looks like your JSON data can have a set of keys with similar values (Attribute) and you can't know how many of them might be in the data.
For this case, you can use a map[string]json.RawMessage as the starting entity to unmarshal to
var e map[string]json.RawMessage
if err := json.Unmarshal([]byte(jsonData), &e); err != nil {
panic(err)
}
You can then range over the values to see if you can unmarshal them into Attribute type
for k, v := range e {
var a Attribute
if err := json.Unmarshal(v, &a); err == nil {
log.Printf("Got attribute %s: %s", k, string(v))
}
}
Run it on playground