json parsing of int64 in go; null values

json go int64
kazamatzuri picture kazamatzuri · Jun 12, 2012 · Viewed 7.8k times · Source

I'm trying to parse a json stream in Go. I've created a simplified example:

 package main
 import (
    "encoding/json"
    "fmt"
 )

 var d = []byte(`{ "world":[{"data": 2251799813685312}, {"data": null}]}`)

 type jsonobj struct{ World []World }
 type World struct{ Data int64 }

 func main() {
    var data jsonobj
    jerr := json.Unmarshal(d, &data)
    fmt.Println(jerr)
 }

this will give me 

go run testmin.go
json: cannot unmarshal null into Go value of type int64

I've found a nullable int64 in the sql package, but json doesn't seem to be able to handle it.

Is there a nullable int64 type that json can handle? If possible I'd be happy with the json null being translated to, -1 or MinValue.

Thank you for your input, Fabian

Answer

tux21b picture tux21b · Jun 12, 2012

Just use a *int64. A pointer can either be nil or it can point to an int64 with an associated value and they work fine with Go's JSON package.

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