Golang json Unmarshal "unexpected end of JSON input"

You can also get this error if you're using json.RawMessage in an unexported field. For example, the following code produces the same error:

package main

import (
    "encoding/json"
    "fmt"
)

type MyJson struct {
    Foo bool `json:"foo"`
    bar json.RawMessage `json:"bar"`
}

type Bar struct {
    X int `json:"x"`
}

var respBytes = []byte(`
{
  "foo": true,
  "bar": { "x": 10 }
}`)

func main() {
    var myJson MyJson
    err := json.Unmarshal(respBytes, &myJson)
    if err != nil {
        fmt.Println(err)
        return
    }
    myBar := new(Bar)
    err = json.Unmarshal(myJson.bar, myBar)
    fmt.Println(err)
}

If you export "MyJson.bar" field (e.g. -> "MyJson.Bar", then the code works.

The unexpected end of JSON input is the result of a syntax error in the JSON input (likely a missing ", }, or ]). The error does not depend on the type of the value that you are decoding to.

I ran the code with the example JSON input on the playground. It runs without error.

The code does not decode anything because the result field is not exported. If you export the result field:

type ResultStruct struct {
   Result []map[string]string
}

then the input is decoded as shown in this playground example.

I suspect that you are not reading the entire response body in your application. I suggest decoding the JSON input using:

err := json.NewDecoder(resp.Body).Decode(&jsonData)

The decoder reads directly from the response body.