问题
I'm trying to fetch a list of top submissions for a particular Subreddit using their open API:
package main
import (
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"os"
)
const api_endpoint = "http://www.reddit.com/r/%s/top.json?t=all&limit=100"
func main() {
// Get console argument 'subreddit' and format the API endpoint URL.
subreddit := os.Args[1]
top_by_subreddit_endpoint := fmt.Sprintf(api_endpoint, subreddit)
// Hit the API service.
response, err := http.Get(top_by_subreddit_endpoint)
if err != nil {
//Perror(err)
} else {
defer response.Body.Close()
content, err := ioutil.ReadAll(response.Body)
if err != nil {
//Perror(err)
} else {
var top_submissions Submission
json.Unmarshal(content, &top_submissions)
}
}
}
type ByCreated []Submission
func (a ByCreated) Len() int { return len(a) }
func (a ByCreated) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
func (a ByCreated) Less(i, j int) bool { return a[i].Created < a[j].Created }
type Submission struct {
Domain string `json:"domain"`
BannedBy string `json:"banned_by"`
MediaEmbed string `json:"media_embed"`
Subreddit string `json:"subreddit"`
SelftextHtml string `json:"selftext_html"`
Selftext string `json:"selftext"`
Likes bool `json:"likes"`
SecureMedia string `json:"secure_media"`
LinkFlairText string `json:"link_flair_text"`
Id string `json:"id"`
Gilded int `json:"gilded"`
SecureMediaEmbed string `json:"secure_media_embed"`
Clicked bool `json:"clicked"`
Stickied bool `json:"stickied"`
Author string `json:"author"`
Media string `json:"media"`
Score int `json:"score"`
ApprovedBy string `json:"approved_by"`
Over18 bool `json:"over_18"`
Hidden bool `json:"hidden"`
Thumbnail string `json:"thumbnail"`
SubredditId string `json:"subreddit_id"`
Edited int `json:"edited"`
LinkFlairCssClass string `json:"link_flair_css_class"`
AuthorFlairCssClass string `json:"author_flair_css_class"`
Downs int `json:"downs"`
Saved bool `json:"saved"`
IsSelf bool `json:"is_self"`
Permalink string `json:"permalink"`
Name string `json:"name"`
Created int `json:"created"`
Url string `json:"url"`
AuthorFlairText string `json:"author_flair_text"`
Title string `json:"title"`
CreatedUtc int `json:"created_utc"`
Ups int `json:"ups"`
NumComments int `json:"num_comments"`
Visited bool `json:"visited"`
NumReports string `json:"num_reports"`
Distinguished string `json:"distinguished"`
}
Unfortunately this doesn't work because the actual submission list is nested inside the response. How can I unmarshal the data json array (it's within the children element) into an array of type Submission struct?
{
"kind": "Listing",
"data": {
"modhash": "1wcy5kngm9408522707f8e319ca825af342a5b3c460ca7c928",
"children": [
{
"kind": "t3",
"data": {
"domain": "self.Smite",
"banned_by": null,
"media_embed": {},
"subreddit": "Smite",
"selftext_html": "<!-- SC_OFF --><div class=\"md\"><p>Hello Smite community - how&#39;s it going? My name is Steve, but you can just call me Proto. I&#39;m a forum moderator and content creator for Beyond Entertainment - a site which specializes in gaming news surrounding competitive console gaming and all around video games news. I&#39;ve been around competitive gaming since 2007 back in the Halo 2 MLG days and have been hooked ever since. I&#39;m not here to talk about myself though - and although I&#39;m not a Smite player - I&#39;m here to talk about a company who is becoming involved with the Smite community that goes by the name Bonafide Boarding <a href=\"https://twitter.com/LiveBNFD\">https://twitter.com/LiveBNFD</a> </p>\n\n<p>Now you might be asking yourself why am I writing this? First, these 2 tweets drew my attention in regards to Bonafide Boarding <a href=\"https://twitter.com/BonafideBCC\">https://twitter.com/BonafideBCC</a> - as well as Billy and Brad - working with people in the competitive Smite community </p>\n\n<p><a href=\"https://twitter.com/LiveBNFD/status/441044741699149825\">https://twitter.com/LiveBNFD/status/441044741699149825</a> </p>\n\n<p><a href=\"https://twitter.com/HiRezNabil\">https://twitter.com/HiRezNabil</a> (pictures with Brad under this Twitter user&#39;s photos - Brad confirmed in the AGL Facebook cover photo as well just for verification) </p>\n\n<p>Well - I&#39;m writing this because the owners of the Bonafide Boarding Clothing company, Brad Weir and Billy Lutz <a href=\"https://twitter.com/MrBillyLutz\">https://twitter.com/MrBillyLutz</a> have past experience in competitive gaming. including running their own league of Halo tournaments in 2012 and 2013. However, it&#39;s not a good past - and to put it as blunt as possible - the two together are frauds who stole money from the Halo community and owe professional Halo players thousands of dollars from their Halo events - at the time known as AGL (Arena Gaming League) <a href=\"https://www.facebook.com/ArenaGamingLeague\">https://www.facebook.com/ArenaGamingLeague</a> (Brad Weir is in the cover photo, on the right, in the red t shirt interviewing the person on the left) </p>\n\n<p>Brad and Billy had their first AGL Halo event in August of 2012 - and in 2013 is when the problems began. While there is a lot more to talk about then what can be posted here, I will basically go into how AGL ended and how Halo players were scammed out of thousands of dollars in owed prize money - and to this day, no one has received any money from AGL, Brad or Billy for most of the 2013 AGL Halo tournaments. </p>\n\n<p>AGL had announced an event to held in Indianapolis, Indiana on November 1-3, 2013 called the &quot;AGL 10K&quot;. It was made out to be their biggest event yet - held at a brand new LAN center and promising the most prize money at any AGL event thus far at the time. However, just days before the event was scheduled to take place, it was cancelled as noted here with a direct quote from AGL/Brad in the article below </p>\n\n<p><a href=\"http://teambeyond.net/agl-10k-cancelled/\">http://teambeyond.net/agl-10k-cancelled/</a> </p>\n\n<p>This also led to players not being able to get refunds for their team passes which many had already purchased for the event (note the dates on the tweets shown below) </p>\n\n<p><a href=\"https://twitter.com/jCreelz/status/394116351402737664\">https://twitter.com/jCreelz/status/394116351402737664</a> </p>\n\n<p><a href=\"https://twitter.com/Ninja_Invictus/status/393922514247643136\">https://twitter.com/Ninja_Invictus/status/393922514247643136</a> </p>\n\n<p>Not long after this event was cancelled, AGL completely shut down, seemingly out of nowhere - confirmed in this forum post by Brad himself on the Beyond Entertainment forums </p>\n\n<p><a href=\"http://teambeyond.net/forum/index.php?/topic/2238-agl-closes-down-statement/page-50?p=108159#entry108159\">http://teambeyond.net/forum/index.php?/topic/2238-agl-closes-down-statement/page-50?p=108159#entry108159</a> </p>\n\n<p>Since AGL has shut down, there has been little to absolutely no contact from Brad, Billy, or anyone associated with AGL in terms of paying not only the professional players who are owed prize money, but commentators and staff from the event as well who were not paid and had no travel costs covered. </p>\n\n<p>The following are all tweets from professional Halo players who have still NEVER been paid by Brad Weir, Billy Lutz, or AGL as a whole. </p>\n\n<p><a href=\"https://twitter.com/MLGACE/statuses/408356773037232128\">https://twitter.com/MLGACE/statuses/408356773037232128</a> </p>\n\n<p><a href=\"https://twitter.com/FormaL_tK/statuses/408400562372108288\">https://twitter.com/FormaL_tK/statuses/408400562372108288</a> </p>\n\n<p><a href=\"https://twitter.com/Naded_MLG/statuses/426908120879607808\">https://twitter.com/Naded_MLG/statuses/426908120879607808</a> </p>\n\n<p><a href=\"https://twitter.com/xPROVERBx/statuses/426975901583425536\">https://twitter.com/xPROVERBx/statuses/426975901583425536</a> </p>\n\n<p><a href=\"https://twitter.com/enable_/status/426952260317220864\">https://twitter.com/enable_/status/426952260317220864</a> </p>\n\n<p><a href=\"https://twitter.com/BRIZZ_Legit/status/426959849729974272\">https://twitter.com/BRIZZ_Legit/status/426959849729974272</a> </p>\n\n<p>This recent tweet is also from someone who bought t shirts from Bonafide Boarding, Brad and Billy&#39;s clothing company, and it appears they were screwed as well. </p>\n\n<p><a href=\"https://twitter.com/shellyteachesk2/status/447432597288017920\">https://twitter.com/shellyteachesk2/status/447432597288017920</a> </p>\n\n<p>The reason I am writing all this is just to warn you guys as a community to not fall into the trap the Halo community fell into in 2013. Do not support these guys - and most importantly - do not give them your money. I have loved competitive gaming for a long time, and I want nothing more than to see it continue to grow. The last thing I want to see happen is what happened to the Halo community in 2013 at the hands of Brad Weir, Billy Lutz, and the AGL company as a whole. Brad, Billy, and Bonafide Boarding as a whole is nothing but a scam and these 2 owe a lot of people a lot of money. Hopefully you guys can take this to heart and not support these two scumbags who have still yet to pay thousands of dollars to people who rightfully won money in their tournaments. Thank you for reading. </p>\n\n<ul>\n<li>Proto</li>\n</ul>\n</div><!-- SC_ON -->",
"selftext": "Hello Smite community - how's it going? My name is Steve, but you can just call me Proto. I'm a forum moderator and content creator for Beyond Entertainment - a site which specializes in gaming news surrounding competitive console gaming and all around video games news. I've been around competitive gaming since 2007 back in the Halo 2 MLG days and have been hooked ever since. I'm not here to talk about myself though - and although I'm not a Smite player - I'm here to talk about a company who is becoming involved with the Smite community that goes by the name Bonafide Boarding https://twitter.com/LiveBNFD \n\nNow you might be asking yourself why am I writing this? First, these 2 tweets drew my attention in regards to Bonafide Boarding https://twitter.com/BonafideBCC - as well as Billy and Brad - working with people in the competitive Smite community \n\nhttps://twitter.com/LiveBNFD/status/441044741699149825 \n\nhttps://twitter.com/HiRezNabil (pictures with Brad under this Twitter user's photos - Brad confirmed in the AGL Facebook cover photo as well just for verification) \n\nWell - I'm writing this because the owners of the Bonafide Boarding Clothing company, Brad Weir and Billy Lutz https://twitter.com/MrBillyLutz have past experience in competitive gaming. including running their own league of Halo tournaments in 2012 and 2013. However, it's not a good past - and to put it as blunt as possible - the two together are frauds who stole money from the Halo community and owe professional Halo players thousands of dollars from their Halo events - at the time known as AGL (Arena Gaming League) https://www.facebook.com/ArenaGamingLeague (Brad Weir is in the cover photo, on the right, in the red t shirt interviewing the person on the left) \n\nBrad and Billy had their first AGL Halo event in August of 2012 - and in 2013 is when the problems began. While there is a lot more to talk about then what can be posted here, I will basically go into how AGL ended and how Halo players were scammed out of thousands of dollars in owed prize money - and to this day, no one has received any money from AGL, Brad or Billy for most of the 2013 AGL Halo tournaments. \n\nAGL had announced an event to held in Indianapolis, Indiana on November 1-3, 2013 called the \"AGL 10K\". It was made out to be their biggest event yet - held at a brand new LAN center and promising the most prize money at any AGL event thus far at the time. However, just days before the event was scheduled to take place, it was cancelled as noted here with a direct quote from AGL/Brad in the article below \n\nhttp://teambeyond.net/agl-10k-cancelled/ \n\nThis also led to players not being able to get refunds for their team passes which many had already purchased for the event (note the dates on the tweets shown below) \n\nhttps://twitter.com/jCreelz/status/394116351402737664 \n\nhttps://twitter.com/Ninja_Invictus/status/393922514247643136 \n\nNot long after this event was cancelled, AGL completely shut down, seemingly out of nowhere - confirmed in this forum post by Brad himself on the Beyond Entertainment forums \n\nhttp://teambeyond.net/forum/index.php?/topic/2238-agl-closes-down-statement/page-50?p=108159#entry108159 \n\nSince AGL has shut down, there has been little to absolutely no contact from Brad, Billy, or anyone associated with AGL in terms of paying not only the professional players who are owed prize money, but commentators and staff from the event as well who were not paid and had no travel costs covered. \n\nThe following are all tweets from professional Halo players who have still NEVER been paid by Brad Weir, Billy Lutz, or AGL as a whole. \n\nhttps://twitter.com/MLGACE/statuses/408356773037232128 \n\nhttps://twitter.com/FormaL_tK/statuses/408400562372108288 \n\nhttps://twitter.com/Naded_MLG/statuses/426908120879607808 \n\nhttps://twitter.com/xPROVERBx/statuses/426975901583425536 \n\nhttps://twitter.com/enable_/status/426952260317220864 \n\nhttps://twitter.com/BRIZZ_Legit/status/426959849729974272 \n\nThis recent tweet is also from someone who bought t shirts from Bonafide Boarding, Brad and Billy's clothing company, and it appears they were screwed as well. \n\nhttps://twitter.com/shellyteachesk2/status/447432597288017920 \n\nThe reason I am writing all this is just to warn you guys as a community to not fall into the trap the Halo community fell into in 2013. Do not support these guys - and most importantly - do not give them your money. I have loved competitive gaming for a long time, and I want nothing more than to see it continue to grow. The last thing I want to see happen is what happened to the Halo community in 2013 at the hands of Brad Weir, Billy Lutz, and the AGL company as a whole. Brad, Billy, and Bonafide Boarding as a whole is nothing but a scam and these 2 owe a lot of people a lot of money. Hopefully you guys can take this to heart and not support these two scumbags who have still yet to pay thousands of dollars to people who rightfully won money in their tournaments. Thank you for reading. \n\n- Proto",
"likes": true,
"secure_media": null,
"link_flair_text": null,
"id": "21dp8c",
"gilded": 0,
"secure_media_embed": {},
"clicked": false,
"stickied": false,
"author": "Proto__",
"media": null,
"score": 1038,
"approved_by": null,
"over_18": false,
"hidden": false,
"thumbnail": "",
"subreddit_id": "t5_2stl8",
"edited": 1395865323,
"link_flair_css_class": null,
"author_flair_css_class": null,
"downs": 274,
"saved": false,
"is_self": true,
"permalink": "/r/Smite/comments/21dp8c/a_warning_to_the_smite_community_bonafide/",
"name": "t3_21dp8c",
"created": 1395828838,
"url": "http://www.reddit.com/r/Smite/comments/21dp8c/a_warning_to_the_smite_community_bonafide/",
"author_flair_text": null,
"title": "A warning to the Smite community (Bonafide Boarding Clothing company)",
"created_utc": 1395800038,
"ups": 1312,
"num_comments": 200,
"visited": false,
"num_reports": null,
"distinguished": null
}
}],
}
}
}
回答1:
Create a few more structs (just like your Submission struct) that mimic the exact shape of the JSON. Unmarshall into one of the top-most structs, then access the appropriate member of the struct.
回答2:
You have 2 problems.
Your struct is incorrect,
MediaEmbed,Media,SecureMediaandSecureMediaEmbedcan be objects not strings,Editedcan be "false", dates are floats not ints.You have to use extra structs,but you can embed them.
Example :
package main
import (
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"os"
"sort"
)
const (
api_endpoint = "http://www.reddit.com/r/%s/top.json?t=all&limit=100"
)
func main() {
var top_submissions struct {
Kind interface{}
Data struct {
ModHash interface{}
Children []struct {
Kind interface{}
Data Submission
}
After string
Before interface{}
}
}
subreddit := os.Args[1]
top_by_subreddit_endpoint := fmt.Sprintf(api_endpoint, subreddit)
// Hit the API service.
response, err := http.Get(top_by_subreddit_endpoint)
if err != nil {
panic(err)
} else {
defer response.Body.Close()
content, err := ioutil.ReadAll(response.Body)
if err != nil {
//Perror(err)
} else {
if err := json.Unmarshal(content, &top_submissions); err != nil {
panic(err)
}
}
}
byCreated := make(ByCreated, len(top_submissions.Data.Children))
for i, v := range top_submissions.Data.Children {
byCreated[i] = v.Data
}
sort.Sort(byCreated)
for _, v := range byCreated {
fmt.Printf("%#v\n", v)
}
}
type ByCreated []Submission
func (a ByCreated) Len() int { return len(a) }
func (a ByCreated) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
func (a ByCreated) Less(i, j int) bool { return a[i].Created < a[j].Created }
type Submission struct {
Domain string `json:"domain"`
BannedBy string `json:"banned_by"`
MediaEmbed json.RawMessage `json:"media_embed"`
Subreddit string `json:"subreddit"`
SelftextHtml string `json:"selftext_html"`
Selftext string `json:"selftext"`
Likes bool `json:"likes"`
SecureMedia json.RawMessage `json:"secure_media"`
LinkFlairText string `json:"link_flair_text"`
Id string `json:"id"`
Gilded int `json:"gilded"`
SecureMediaEmbed json.RawMessage `json:"secure_media_embed"`
Clicked bool `json:"clicked"`
Stickied bool `json:"stickied"`
Author string `json:"author"`
Media json.RawMessage `json:"media"`
Score int `json:"score"`
ApprovedBy string `json:"approved_by"`
Over18 bool `json:"over_18"`
Hidden bool `json:"hidden"`
Thumbnail string `json:"thumbnail"`
SubredditId string `json:"subreddit_id"`
Edited interface{} `json:"edited"` //this can be false
LinkFlairCssClass string `json:"link_flair_css_class"`
AuthorFlairCssClass string `json:"author_flair_css_class"`
Downs int `json:"downs"`
Saved bool `json:"saved"`
IsSelf bool `json:"is_self"`
Permalink string `json:"permalink"`
Name string `json:"name"`
Created float32 `json:"created"`
Url string `json:"url"`
AuthorFlairText string `json:"author_flair_text"`
Title string `json:"title"`
CreatedUtc float32 `json:"created_utc"`
Ups int `json:"ups"`
NumComments int `json:"num_comments"`
Visited bool `json:"visited"`
NumReports string `json:"num_reports"`
Distinguished string `json:"distinguished"`
}
来源：https://stackoverflow.com/questions/23317191/using-unmarshal-to-fetch-specific-json-fields-from-response