(un)marshalling json golang not working - json

Question

I'm playing with Go and am stumped as to why json encode and decode don't work for me
I think i copied the examples almost verbatim, but the output says both marshal and unmarshal return no data. They also don't give an error.
can anyone hint to where i'm going wrong?
my sample code: Go playground
package main
import "fmt"
import "encoding/json"
type testStruct struct {
clip string `json:"clip"`
}
func main() {
//unmarshal test
var testJson = "{\"clip\":\"test\"}"
var t testStruct
var jsonData = []byte(testJson)
err := json.Unmarshal(jsonData, &t)
if err != nil {
fmt.Printf("There was an error decoding the json. err = %s", err)
return
}
fmt.Printf("contents of decoded json is: %#v\r\n", t)
//marshal test
t.clip = "test2"
data, err := json.Marshal(&t)
if err != nil {
fmt.Printf("There was an error encoding the json. err = %s", err)
return
}
fmt.Printf("encoded json = %s\r\n", string(data))
}
output:
contents of decoded json is: main.testStruct{clip:""}
encoded json = {}
in both outputs I would have expected to see the decoded or encoded json

Answer 1

For example,
package main
import "fmt"
import "encoding/json"
type testStruct struct {
Clip string `json:"clip"`
}
func main() {
//unmarshal test
var testJson = "{\"clip\":\"test\"}"
var t testStruct
var jsonData = []byte(testJson)
err := json.Unmarshal(jsonData, &t)
if err != nil {
fmt.Printf("There was an error decoding the json. err = %s", err)
return
}
fmt.Printf("contents of decoded json is: %#v\r\n", t)
//marshal test
t.Clip = "test2"
data, err := json.Marshal(&t)
if err != nil {
fmt.Printf("There was an error encoding the json. err = %s", err)
return
}
fmt.Printf("encoded json = %s\r\n", string(data))
}
Output:
contents of decoded json is: main.testStruct{Clip:"test"}
encoded json = {"clip":"test2"}
Playground:
http://play.golang.org/p/3XaVougMTE
Export the struct fields.
type testStruct struct {
Clip string `json:"clip"`
}
Exported identifiers
An identifier may be exported to permit access to it from another
package. An identifier is exported if both:
the first character of the identifier's name is a Unicode upper case letter (Unicode class "Lu"); and
the identifier is declared in the package block or it is a field name or method name.
All other identifiers are not exported.

Answer 2

Capitalize names of structure fields
type testStruct struct {
clip string `json:"clip"` // Wrong. Lowercase - other packages can't access it
}
Change to:
type testStruct struct {
Clip string `json:"clip"`
}

Answer 3

In my case, my struct fields were capitalized but I was still getting the same error.
Then I noticed that the casing of my fields was different. I had to use underscores in my request.
For eg:
My request body was:
{
"method": "register",
"userInfo": {
"fullname": "Karan",
"email": "email#email.com",
"password": "random"
}
}
But my golang struct was:
type AuthRequest struct {
Method string `json:"method,omitempty"`
UserInfo UserInfo `json:"user_info,omitempty"`
}
I solved this by modifying my request body to:
{
"method": "register",
"user_info": {
"fullname": "Karan",
"email": "email#email.com",
"password": "random"
}
}