EC
json.InvalidUnmarshalError
GoERRORCommonJSON

json: Unmarshal(non-pointer …)

Quick Answer

Always pass a non-nil pointer to json.Unmarshal, e.g. &myStruct not myStruct.

What this means

Returned when json.Unmarshal is called with a non-pointer or nil pointer as the target. The JSON is valid; the issue is the destination argument.

Why it happens
  1. 1Passing a value type instead of a pointer to Unmarshal
  2. 2Passing a nil pointer that has not been initialized

Fix

Pass pointer address

Pass pointer address
var v MyStruct
err := json.Unmarshal(data, &v) // correct
// json.Unmarshal(data, v) is wrong

Why this works

json.Unmarshal requires a pointer so it can modify the value through reflection.

Code examples
Correct usagego
var v MyStruct
err := json.Unmarshal(data, &v)
Detectgo
var ie *json.InvalidUnmarshalError
if errors.As(err, &ie) {
    log.Printf("bad target type: %v", ie.Type)
}
Initialize pointergo
v := new(MyStruct)
err := json.Unmarshal(data, v)
Sources
Official documentation ↗

Go standard library

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