Heart returns expected SyntaxError value when deserializing nested JSON structures

Question

I am trying to deserialize Spotify JSON metadata from a web API ( spec ). I use hyper to retrieve JSON from the server and serde to turn JSON into what I really can use in Rust. The JSON retrieved from the server is just fine, but when I try to turn JSON into an object that can be used in Rust patches and throws an error:

thread '<main>' panicked at 'called 'Result::unwrap()' on an 'Err' value: SyntaxError("expected value", 11, 21)', ../src/libcore/result.rs:746

This does not help to a lesser extent, because it does not indicate where everything is going wrong. While searching the Internet, I came across a serious problem , which makes me think that the problem is related to the nested JSON structure.

Can anyone see where everything went wrong? Correcting the error would be the best solution for me, but if another box would be the best solution, I would also like to hear it. I have already tried rustc-serialize, but this box cannot handle type variables in json.

The code I use is:

#![feature(custom_derive, plugin)]
#![plugin(serde_macros)]
#![feature(custom_attribute)]

extern crate hyper;
extern crate serde;
extern crate serde_json;

use std::io::Read;
use hyper::Client;
use hyper::header::Connection;

#[derive(Serialize, Deserialize)]
struct Track_Full {
    album: Album_Simp,
    artists: Vec<Artist_Simp>,
    available_markets: Vec<String>,
    disc_number: u8,
    duration_ms: u32,
    explicit: bool,
    external_ids: External_IDs,
    external_urls: External_URLs,
    href: String,
    id: String,
    name: String,
    popularity: u8,
    preview_url: String,
    track_number: u8,
    #[serde(rename="type")]
    _type: String,
    uri: String
}

#[derive(Serialize, Deserialize)]
struct Album_Simp {
    album_type: String,
    available_markets: Vec<String>,
    external_urls: External_URLs,
    href: String,
    id: String,
    images: Vec<Image>,
    name: String,
    #[serde(rename="type")]
    _type: String,
    uri: String
}

#[derive(Serialize, Deserialize)]
struct Artist_Simp {
    external_urls: External_URLs,
    href: String,
    id: String,
    name: String,
    #[serde(rename="type")]
    _type: String,
    uri: String
}

#[derive(Serialize, Deserialize)]
struct External_IDs {
    isrc: String
}

#[derive(Serialize, Deserialize)]
struct External_URLs {
    spotify: String
}

#[derive(Serialize, Deserialize)]
struct Image {
    height: u8,
    url: String,
    width: u8
}

fn main() {
    // Create a client.
    let mut client = Client::new();

    // Creating an outgoing request.
    let mut res = client.get("https://api.spotify.com/v1/tracks/0eGsygTp906u18L0Oimnem")
        // set a header
        .header(Connection::close())
        // let 'er go!
        .send().unwrap();

    // Read the Response.
    let mut body = String::new();
    res.read_to_string(&mut body).unwrap();

    println!("{}", body);

    let deserialized: Track_Full = serde_json::from_str(&body).unwrap();
}

JSON:

{
  "album" : {
    "album_type" : "album",
    "available_markets" : [ "AD", "AR", "AT", "AU", "BE", "BG", "BO", "BR", "CH", "CL", "CO", "CR", "CY", "CZ", "DE", "DK", "DO", "EC", "EE", "ES", "FI", "FR", "GR", "GT", "HK", "HN", "HU", "IE", "IS", "IT", "LI", "LT", "LU", "LV", "MC", "MT", "MY", "NI", "NL", "NO", "NZ", "PA", "PE", "PH", "PL", "PT", "PY", "RO", "SE", "SG", "SI", "SK", "SV", "TR", "TW", "UY" ],
    "external_urls" : {
      "spotify" : "https://open.spotify.com/album/6TJmQnO44YE5BtTxH8pop1"
    },
    "href" : "https://api.spotify.com/v1/albums/6TJmQnO44YE5BtTxH8pop1",
    "id" : "6TJmQnO44YE5BtTxH8pop1",
    "images" : [ {
      "height" : 640,
      "url" : "https://i.scdn.co/image/8e13218039f81b000553e25522a7f0d7a0600f2e",
      "width" : 629
    }, {
      "height" : 300,
      "url" : "https://i.scdn.co/image/8c1e066b5d1045038437d92815d49987f519e44f",
      "width" : 295
    }, {
      "height" : 64,
      "url" : "https://i.scdn.co/image/d49268a8fc0768084f4750cf1647709e89a27172",
      "width" : 63
    } ],
    "name" : "Hot Fuss",
    "type" : "album",
    "uri" : "spotify:album:6TJmQnO44YE5BtTxH8pop1"
  },
  "artists" : [ {
    "external_urls" : {
      "spotify" : "https://open.spotify.com/artist/0C0XlULifJtAgn6ZNCW2eu"
    },
    "href" : "https://api.spotify.com/v1/artists/0C0XlULifJtAgn6ZNCW2eu",
    "id" : "0C0XlULifJtAgn6ZNCW2eu",
    "name" : "The Killers",
    "type" : "artist",
    "uri" : "spotify:artist:0C0XlULifJtAgn6ZNCW2eu"
  } ],
  "available_markets" : [ "AD", "AR", "AT", "AU", "BE", "BG", "BO", "BR", "CH", "CL", "CO", "CR", "CY", "CZ", "DE", "DK", "DO", "EC", "EE", "ES", "FI", "FR", "GR", "GT", "HK", "HN", "HU", "IE", "IS", "IT", "LI", "LT", "LU", "LV", "MC", "MT", "MY", "NI", "NL", "NO", "NZ", "PA", "PE", "PH", "PL", "PT", "PY", "RO", "SE", "SG", "SI", "SK", "SV", "TR", "TW", "UY" ],
  "disc_number" : 1,
  "duration_ms" : 222075,
  "explicit" : false,
  "external_ids" : {
    "isrc" : "USIR20400274"
  },
  "external_urls" : {
    "spotify" : "https://open.spotify.com/track/0eGsygTp906u18L0Oimnem"
  },
  "href" : "https://api.spotify.com/v1/tracks/0eGsygTp906u18L0Oimnem",
  "id" : "0eGsygTp906u18L0Oimnem",
  "name" : "Mr. Brightside",
  "popularity" : 74,
  "preview_url" : "https://p.scdn.co/mp3-preview/934da7155ec15deb326635d69d050543ecbee2b4",
  "track_number" : 2,
  "type" : "track",
  "uri" : "spotify:track:0eGsygTp906u18L0Oimnem"
}

Answer 1

You tried to parse some JSON, and it failed. When you called unwrapon Result, the program panicked because of this error:

SyntaxError("expected value", 11, 21)

The documentation forSyntaxError indicates that numbers are a row and a column of errors. Row 11, column 21:

      "height" : 640,
                     ^

, , u8, 8- . 0-255. 640 . u32 JSON.

---

, Rust CamelCase . External_URLs → ExternalUrls. .