Convert DynamoDB JSON to AttributeValue, Go Object or Json - json

Question

I am trying to convert simple DynamoDB Object string:
{
"Item": {
"Id": {
"S": "db31"
},
"CreateTime": {
"N": "1647882237618915000"
}
}
to either dynamodb.AttributeValue and then map to a go object (go type structure) or convert to a simple JSON go object.
I think, there are similar answers (1, 2, 3) in Java, but I didn't find a similar implementation in Golang.

Answer 1

You could create a struct type and use json.Unmarshal to unmarshal the JSON string like this:
package main
import (
"encoding/json"
"fmt"
"os"
)
type Record struct {
Item struct {
Id struct {
S string
}
CreateTime struct {
N string
}
}
}
func main() {
str := `{
"Item": {
"Id": {
"S": "db31"
},
"CreateTime": {
"N": "1647882237618915000"
}
}
}`
var record Record
if err := json.Unmarshal([]byte(str), &record); err != nil {
fmt.Fprintf(os.Stderr, "unmarshal failed: %v", err)
os.Exit(1)
}
fmt.Printf("%s %s", record.Item.Id.S, record.Item.CreateTime.N)
}
If you want a different approach, and want to transform the result into a structure that is different than the JSON, you could use a library like gjson.
Here is an example "flattening" the result into a simpler struct:
package main
import (
"fmt"
"github.com/tidwall/gjson"
)
type Record struct {
Id string
CreateTime string
}
func main() {
str := `{
"Item": {
"Id": {
"S": "db31"
},
"CreateTime": {
"N": "1647882237618915000"
}
}
}`
values := gjson.GetMany(str, "Item.Id.S", "Item.CreateTime.N")
record := Record{
Id: values[0].Str,
CreateTime: values[1].Str,
}
fmt.Printf("%s %s", record.Id, record.CreateTime)
}