Golang: Unmarshal JSON Object results in empty map

Question

I've been stuck trying to unmarshal a json object. I am not getting any errors but I am getting an empty map afterwards. I'm new to go so I'm still trying to wrap my head around some of the language constructs.

Here is what my data source looks like

{ 
    "animationStates": {
        "idle": {
            "numFrames": 4,
            "frames": [
                {
                    "frame": {"x":43,"y":106,"w":12,"h":15},
                    "rotated": false
                },
                {
                    "frame": {"x":1,"y":143,"w":12,"h":14},
                    "rotated": false
                },
                {
                    "frame": {"x":71,"y":132,"w":12,"h":14},
                    "rotated": false
                },
                {
                    "frame": {"x":15,"y":126,"w":12,"h":15},
                    "rotated": true 
                }
            ]
        },
        "run": {
            "numFrames": 10,
            "frames": [
                {
                    "frame": {"x":73,"y":82,"w":12,"h":15},
                    "rotated": false
                },
                {
                    "frame": {"x":29,"y":125,"w":12,"h":15},
                    "rotated": false
                },
                {
                    "frame": {"x":33,"y":36,"w":12,"h":16},
                    "rotated": false
                },
                {
                    "frame": {"x":1,"y":107,"w":12,"h":16},
                    "rotated": false
                },
                {
                    "frame": {"x":1,"y":89,"w":12,"h":16},
                    "rotated": false
                },
                {
                    "frame": {"x":17,"y":54,"w":12,"h":16},
                    "rotated": false
                },
                {
                    "frame": {"x":1,"y":125,"w":12,"h":16},
                    "rotated": false
                }
                {
                    "frame": {"x":15,"y":143,"w":12,"h":14},
                    "rotated": false
                },
                {
                    "frame": {"x":29,"y":142,"w":12,"h":14},
                    "rotated": false
                },
                {
                    "frame": {"x":72,"y":99,"w":12,"h":15},
                    "rotated": false
                }
            ]
        },
        "roll": {
            "numFrames": 5,
            "frames": [
                {
                    "frame": {"x":71,"y":116,"w":12,"h":14},
                    "rotated": false
                },
                {
                    "frame": {"x":71,"y":148,"w":12,"h":10},
                    "rotated": false
                },
                {
                    "frame": {"x":73,"y":47,"w":12,"h":15},
                    "rotated": false
                },
                {
                    "frame": {"x":57,"y":147,"w":12,"h":11},
                    "rotated": false
                },
                {
                    "frame": {"x":29,"y":108,"w":12,"h":15},
                    "rotated": false
                }
            ]
        },
        "jump": {
            "numFrames": 1,
            "frames": [
                {
                    "frame": {"x":45,"y":54,"w":12,"h":16},
                    "rotated": false
                }
            ]
        },
        "fall": {
            "numFrames": 1,
            "frames": [
                {
                    "frame": {"x":29,"y":90,"w":12,"h":16},
                    "rotated": false
                }
            ]
        },
        "shoot": {
            "numFrames": 5,
            "frames": [
                {
                    "frame": {"x":37,"y":1,"w":14,"h":15},
                    "rotated": false
                },
                {
                    "frame": {"x":17,"y":37,"w":14,"h":15},
                    "rotated": false
                },
                {
                    "frame": {"x":1,"y":37,"w":14,"h":16},
                    "rotated": false
                },
                {
                    "frame": {"x":19,"y":19,"w":14,"h":15},
                    "rotated": false
                },
                {
                    "frame": {"x":1,"y":55,"w":14,"h":15},
                    "rotated": false
                }
            ]
        }
    }
}

and here is the code that I'm using to unmarshal

package main

import (
    "encoding/json"
    "io/ioutil"
)

type AnimationFrame struct {
    Frame struct {
        X int `json:"x"`
        Y int `json:"y"`
        W int `json:"w"`
        H int `json:"h"`
    } `json:"frame"`
    Rotated bool `json:"rotated"`
}

type Animation struct {
    NumFrames int `json:"numFrames"`
    Frames []AnimationFrame `json:"frames"` 
} 

type StateList struct {
    Actions map[string]Animation `json:"animationStates"`
}

func NewAnimation (file string) *StateList {
    list := make(map[string]Animation)
    s := &StateList{list}
    buff, err := ioutil.ReadFile(file)
    check(err)
    json.Unmarshal([]byte(buff), &s)
    return s 
}

func check (e error) {
    if e != nil {
        panic(e)
    }
}

Does anyone see what I'm doing wrong? Thanks.

user5728991 · Accepted Answer · 2016-03-30 04:58:43Z

3

Check and handle the error returned from json.Unmarshal([]byte(buff), &s). You will find that there's an invalid character '{' after array element at offset 1685.

playground example

answered Mar 30, 2016 at 4:58

user5728991

Sign up to request clarification or add additional context in comments.

1 Comment

instantaphex Over a year ago

Thanks! I wasn't sure how to check and handle that unmarshal.

Collectives™ on Stack Overflow

Golang: Unmarshal JSON Object results in empty map

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related