Unmarshal deeply nested json in golang - json

Question

I have an ugly way of unmarshalling the following json, but it requires much manual work. I am looking for a more programmatic way to obtain the various team names, if I didn't know how many teams exactly there were originally. It's truly one of the most poorly structured api's I've come across.
data := []byte(`{
"fantasy_content": {
"copyright": "Data provided by Yahoo! and STATS, LLC",
"league": [
{
"allow_add_to_dl_extra_pos": 0,
"current_week": "1",
"draft_status": "predraft",
"edit_key": "1",
"end_date": "2017-12-25",
"end_week": "16",
"game_code": "nfl",
"is_cash_league": "0",
"is_pro_league": "0",
"league_id": "XXXXX",
"league_key": "XXXX",
"league_type": "private",
"league_update_timestamp": null,
"name": "XXXXXX",
"num_teams": 14,
"renew": "XXXX",
"renewed": "",
"scoring_type": "head",
"season": "2017",
"short_invitation_url": "XXXXX",
"start_date": "2017-09-07",
"start_week": "1",
"url": "XXXXXX",
"weekly_deadline": ""
},
{
"teams": {
"0": {
"team": [
[
{
"team_key": "XXXX"
},
{
"team_id": "1"
},
{
"name": "XXXXX"
},
[],
{
"url": "XXXXX"
},
{
"team_logos": [
{
"team_logo": {
"size": "large",
"XXX"
}
}
]
},
[],
{
"waiver_priority": ""
},
{
"faab_balance": "100"
},
{
"number_of_moves": 0
},
{
"number_of_trades": 0
},
{
"roster_adds": {
"coverage_type": "week",
"coverage_value": "1",
"value": "0"
}
},
[],
{
"league_scoring_type": "head"
},
[],
[],
{
"has_draft_grade": 0
},
[],
[],
{
"managers": [
{
"manager": {
"email": "XXXXX",
"guid": "XX",
"image_url": "https://s.yimg.com/wm/modern/images/default_user_profile_pic_64.png",
"is_commissioner": "1",
"manager_id": "1",
"nickname": "Andrew"
}
}
]
}
]
]
},
"1": {
"team": [
[
{
"team_key": "XXXXX"
},
{
"team_id": "2"
},
{
"name": "XXXXX"
},
[],
{
"url": "XXXXX"
},
{
"team_logos": [
{
"team_logo": {
"size": "large",
"url": "XXXX"
}
}
]
},
[],
{
"waiver_priority": ""
},
{
"faab_balance": "100"
},
{
"number_of_moves": 0
},
{
"number_of_trades": 0
},
{
"roster_adds": {
"coverage_type": "week",
"coverage_value": "1",
"value": "0"
}
},
[],
{
"league_scoring_type": "head"
},
[],
[],
{
"has_draft_grade": 0
},
[],
[],
{
"managers": [
{
"manager": {
"email": "XXXX#yahoo.com",
"guid": "XXXX",
"image_url": "https://s.yimg.com/wm/modern/images/default_user_profile_pic_64.png",
"manager_id": "2",
"nickname": "Andrew"
}
},
{
"manager": {
"email": "XXX#yahoo.com",
"guid": "XX",
"image_url": "https://s.yimg.com/wm/modern/images/default_user_profile_pic_64.png",
"is_comanager": "1",
"manager_id": "15",
"nickname": "XX"
}
}
]
}
]
]
},
"10": {
"team": [
[
{
"team_key": "XXX"
},
{
"team_id": "11"
},
{
"name": "XXX"
},
[],
{
"url": "https://football.fantasysports.yahoo.com/f1/XXX"
},
{
"team_logos": [
{
"team_logo": {
"size": "large",
"url": "https://s.yimg.com/dh/ap/fantasy/nfl/img/icon_01_100.png"
}
}
]
},
[],
{
"waiver_priority": ""
},
{
"faab_balance": "100"
},
{
"number_of_moves": 0
},
{
"number_of_trades": 0
},
{
"roster_adds": {
"coverage_type": "week",
"coverage_value": "1",
"value": "0"
}
},
[],
{
"league_scoring_type": "head"
},
[],
[],
{
"has_draft_grade": 0
},
[],
[],
{
"managers": [
{
"manager": {
"email": "XXX#gmail.com",
"guid": "XX",
"image_url": "https://s.yimg.com/wm/modern/images/default_user_profile_pic_64.png",
"manager_id": "11",
"nickname": "XX"
}
}
]
}
]
]
},
"2": {
"team": [
[
{
"team_key": "371.l.102542.t.3"
},
{
"team_id": "3"
},
{
"name": "XXX"
},
[],
{
"url": "https://football.fantasysports.yahoo.com/f1/XX/3"
},
{
"team_logos": [
{
"team_logo": {
"size": "large",
"url": "https://ct.yimg.com/cy/5603/30147468023_1c705edb29_192sq.jpg?ct=fantasy"
}
}
]
},
[],
{
"waiver_priority": ""
},
{
"faab_balance": "100"
},
{
"number_of_moves": 0
},
{
"number_of_trades": 0
},
{
"roster_adds": {
"coverage_type": "week",
"coverage_value": "1",
"value": "0"
}
},
[],
{
"league_scoring_type": "head"
},
[],
[],
{
"has_draft_grade": 0
},
[],
[],
{
"managers": [
{
"manager": {
"email": "XXXgmail.com",
"guid": "XXXX",
"image_url": "https://s.yimg.com/wv/images/6c93ed606f742d4c075bc091633cc072_64.jpg",
"manager_id": "3",
"nickname": "XX"
}
}
]
}
]
]
},
"3": {
"team": [
[
{
"team_key": "371.l.102542.t.4"
},
{
"team_id": "4"
},
{
"name": "XX"
},
[],
{
"url": "https://football.fantasysports.yahoo.com/f1/XX/4"
},
{
"team_logos": [
{
"team_logo": {
"size": "large",
"url": "https://s.yimg.com/dh/ap/fantasy/nfl/img/icon_10_100.png"
}
}
]
},
[],
{
"waiver_priority": ""
},
{
"faab_balance": "100"
},
{
"number_of_moves": 0
},
{
"number_of_trades": 0
},
{
"roster_adds": {
"coverage_type": "week",
"coverage_value": "1",
"value": "0"
}
},
[],
{
"league_scoring_type": "head"
},
[],
[],
{
"has_draft_grade": 0
},
[],
[],
{
"managers": [
{
"manager": {
"email": "XXX#yahoo.com",
"guid": "XX",
"image_url": "https://s.yimg.com/wm/modern/images/default_user_profile_pic_64.png",
"manager_id": "4",
"nickname": "XX"
}
}
]
}
]
]
},
"8": {
"team": [
[
{
"team_key": "XXX"
},
{
"team_id": "9"
},
{
"name": "XxX"
},
[],
{
"url": "https://football.fantasysports.yahoo.com/f1/XX/9"
},
{
"team_logos": [
{
"team_logo": {
"size": "large",
"url": "https://ct.yimg.com/cy/8393/28682944304_33bda49603_192sq.jpg?ct=fantasy"
}
}
]
},
[],
{
"waiver_priority": ""
},
{
"faab_balance": "100"
},
{
"number_of_moves": 0
},
{
"number_of_trades": 0
},
{
"roster_adds": {
"coverage_type": "week",
"coverage_value": "1",
"value": "0"
}
},
[],
{
"league_scoring_type": "head"
},
[],
[],
{
"has_draft_grade": 0
},
[],
[],
{
"managers": [
{
"manager": {
"email": "XXX",
"guid": "XXX",
"image_url": "https://s.yimg.com/wm/modern/images/default_user_profile_pic_64.png",
"manager_id": "9",
"nickname": "XXX"
}
}
]
}
]
]
},
"count": 14
}
}
],
"refresh_rate": "60",
"time": "110.55207252502ms",
"xml:lang": "en-US",
"yahoo:uri": "/fantasy/v2/league/XXXX/teams"
}
}`)
The following works, but it's a hassle and I have to hard code the different struct values per team, to get data for that team.
type TeamApi_ struct {
TeamKey string `json:"team_key"`
TeamId string `json:"team_id"`
Name string `json:"name"`
}
type LeaguesApi struct {
NumTeams int `json:"num_teams"`
TeamsApi struct {
Zero struct {
TeamsApi_ [][]TeamApi_ `json:"team"`
} `json:"0"`
One struct {
TeamsApi_ [][]TeamApi_ `json:"team"`
} `json:"1"`
Two struct {
TeamsApi_ [][]TeamApi_ `json:"team"`
} `json:"2"`
Three struct {
TeamsApi_ [][]TeamApi_ `json:"team"`
} `json:"3"`
} `json:"teams"`
}
type LeagueApiResult struct {
FantasyContent struct {
LeagueApi []LeaguesApi `json:"league"`
} `json:"fantasy_content"`
}
var Result LeagueApiResult
err := json.Unmarshal(data, &Result)
if err != nil {
fmt.Println(err)
}
fmt.Println(Result.FantasyContent.LeagueApi[1].TeamsApi.One.TeamsApi_[0][2].Name)

Answer 1

You probably want to use a custom JSON unmarshaller for this. You can see an example of how to use one here: http://choly.ca/post/go-json-marshalling/
Since the data is structured the way it is, with the teams section both containing teams and the count field, you'll likely need a fair bit of manual logic in there.
First, you can start by defining the League:
type League struct {
AllowAddToDlExtraPos int `json:"allow_add_to_dl_extra_pos,omitempty"`
CurrentWeek string `json:"current_week,omitempty"`
DraftStatus string `json:"draft_status,omitempty"`
EditKey string `json:"edit_key,omitempty"`
EndDate string `json:"end_date,omitempty"`
EndWeek string `json:"end_week,omitempty"`
GameCode string `json:"game_code,omitempty"`
IsCashLeague string `json:"is_cash_league,omitempty"`
IsProLeague string `json:"is_pro_league,omitempty"`
LeagueID string `json:"league_id,omitempty"`
LeagueKey string `json:"league_key,omitempty"`
LeagueType string `json:"league_type,omitempty"`
LeagueUpdateTimestamp interface{} `json:"league_update_timestamp,omitempty"`
Name string `json:"name,omitempty"`
NumTeams int `json:"num_teams,omitempty"`
Renew string `json:"renew,omitempty"`
Renewed string `json:"renewed,omitempty"`
ScoringType string `json:"scoring_type,omitempty"`
Season string `json:"season,omitempty"`
ShortInvitationURL string `json:"short_invitation_url,omitempty"`
StartDate string `json:"start_date,omitempty"`
StartWeek string `json:"start_week,omitempty"`
URL string `json:"url,omitempty"`
WeeklyDeadline string `json:"weekly_deadline,omitempty"`
Teams []Team `json:"-"`
}
Next, we can define the Team structure the way we want it to look.
type Team struct {
// Declare the fields of a Team
}
And finally, we declare a custom unmarshal function for the League.
func (l *League) UnmarshalJSON(data []byte) error {
type Alias League
aux := &struct {
*Alias
Teams map[string]interface{} `json:"teams"`
}{
Alias: (*Alias)(l),
}
if err := json.Unmarshal(data, aux); err != nil {
return err
}
var teams []Team
for num, team := range aux.Teams {
// Add your code to parse each of the teams from the
// map you declared above.
}
l.Teams = teams
return nil
}
The unmarshal function will be called by Golangs json library automatically when it hits the League structure inside the LeagueApiResult.