Develop Reference

How to process a json response from an API in C#

I've read and reread articles online on how to do this, but it's probably something simple. I'm trying to learn how to process a json response from an API call. I have a simple method I call from Main()
public async void apiTestCall()
{
var httpCall = new HttpClient();
var uri = new Uri("https://api.nasa.gov/mars-photos/api/v1/rovers/curiosity/photos?sol=1000&page=2&api_key=DEMO_KEY");
var result = new DataModel();
var response = await httpCall.GetStringAsync(uri);
result = JsonSerializer.Deserialize<DataModel>(response);
I am expecting "result" to be a DataModel object with the data populated. Right now, there is nothing.
Here is the DataModel class
using System.Collections.Generic;
namespace APITestProject
{
class DataModel
{
public class Camera
{
public int id { get; set; }
public string name { get; set; }
public int rover_id { get; set; }
public string full_name { get; set; }
}
public class Rover
{
public int id { get; set; }
public string name { get; set; }
public string landing_date { get; set; }
public string launch_date { get; set; }
public string status { get; set; }
}
public class Photo
{
public int id { get; set; }
public int sol { get; set; }
public Camera camera { get; set; }
public string img_src { get; set; }
public string earth_date { get; set; }
public Rover rover { get; set; }
}
public class Example
{
public IList<Photo> photos { get; set; }
}
}
}
Any suggestions would be greatly appreciated.
Edit #1: Here is the first 3 entries in the json. I didn't want to post the whole thing but the URL is valid for anyone to run and see the response.
{"photos":[{"id":424926,"sol":1000,"camera":{"id":22,"name":"MAST","rover_id":5,"full_name":"Mast Camera"},"img_src":"http://mars.jpl.nasa.gov/msl-raw-images/msss/01000/mcam/1000ML0044631200305217E01_DXXX.jpg","earth_date":"2015-05-30","rover":{"id":5,"name":"Curiosity","landing_date":"2012-08-06","launch_date":"2011-11-26","status":"active"}},{"id":424927,"sol":1000,"camera":{"id":22,"name":"MAST","rover_id":5,"full_name":"Mast Camera"},"img_src":"http://mars.jpl.nasa.gov/msl-raw-images/msss/01000/mcam/1000MR0044631190503679E04_DXXX.jpg","earth_date":"2015-05-30","rover":
Edit #2: I made some changes based on the comments so far and I used the Paste > Special > JSON as Classes and removed the "wrapper" class. Now I get the populated object. FYI, here is the new class VS generated:
namespace APITestProject
{
public class DataModel
{
public Photo[] photos { get; set; }
}
public class Photo
{
public int id { get; set; }
public int sol { get; set; }
public Camera camera { get; set; }
public string img_src { get; set; }
public string earth_date { get; set; }
public Rover rover { get; set; }
}
public class Camera
{
public int id { get; set; }
public string name { get; set; }
public int rover_id { get; set; }
public string full_name { get; set; }
}
public class Rover
{
public int id { get; set; }
public string name { get; set; }
public string landing_date { get; set; }
public string launch_date { get; set; }
public string status { get; set; }
}
}

Can you try the following amendment
var result = JsonSerializer.Deserialize<DataModel.Example>(response);
as it looks like DataModel.Example is actually the class that you are trying to deserialize to based on the response that comes from the following call -
https://api.nasa.gov/mars-photos/api/v1/rovers/curiosity/photos?sol=1000&page=2&api_key=DEMO_KEY
i.e. It returns an object containing an array of photo objects as you have defined them. As someone else mentioned, no need to encapsulate all of these classes within another class.

You class DataModel just defines other classes, but do not instance them.
According to the data inside the response, you DataModel class should have at least Photos member. It could be type of List<Photo>
class DataModel {
...
public List<Photo> Photos { get; set; }
}
The Photos definition says, that there is some list of photos of Photo type to be expected.

Need assign List object parsed from JSON file to a object property

I trying to build Magic The Gathering card viewer and getting data from json. I have created json file, then copy all and paste special to my class to generate a model. In constructor using json parser I parsed object fine, but when I try to assign to that object property, so I can make method retrieve all cards. But when I trying to do that it says that I can't implicitly assign. I try to assign Cards = cardsCollection; that where it throws an error.
namespace MTGArena
{
public class Cards
{
public class Rootobject
{
static Rootobject()
{
using (StreamReader file = new StreamReader("cards.json"))
{
string json = file.ReadToEnd();
Rootobject cardsCollection = JsonConvert.DeserializeObject<Rootobject>(json);
Cards = cardsCollection;
}
}
public static List<Card> Cards { get; set; }
public static List<Card> GetCards()
{
return Cards;
}
}
}
public class Card
{
public string name { get; set; }
public string set { get; set; }
public Images images { get; set; }
public string type { get; set; }
public string[] cost { get; set; }
public int cmc { get; set; }
public string rarity { get; set; }
public string cid { get; set; }
public int?[] frame { get; set; }
public string artist { get; set; }
public string dfc { get; set; }
public bool collectible { get; set; }
public bool craftable { get; set; }
public int dfcId { get; set; }
public int rank { get; set; }
public string grpId { get; set; }
}
public class Images
{
public string small { get; set; }
public string normal { get; set; }
public string large { get; set; }
public string art_crop { get; set; }
}
}

Change the line:
Rootobject cardsCollection = JsonConvert.DeserializeObject<Rootobject>(json);
for:
var cardsCollection = JsonConvert.DeserializeObject<List<Card>>(json);

You need to use below syntax
IList<Card> cards = cardsCollection;
dont create empty Cards class. It has no use

Geocoding REST call C# Parsing JSON

I'm struggling to pick up the data returned from the Geocoding REST call below (I've removed my app_id and app_code so you cannot run the url as it is below):
https://geocoder.api.here.com/6.2/geocode.json?app_id=[MY APP ID]&app_code=[MY APP CODE]&searchtext=chester
An example reponse can be found here:
https://developer.here.com/documentation/geocoder/topics/quick-start-geocode.html
I know it returns results but I cannot seem to get the results through to my C# application, I don't know if I'm building the class system incorrectly or whether there's something else I'm doing wrong. I've built an application reading the places api with no problem before but this one seems different somehow.
The call returns with a status of OK:
public void GeoCode()
{
// BUILD INITIAL STRING BASED ON PARAMETERS
string url = "https://geocoder.api.here.com/6.2/geocode.json?app_id=gpZ1Ym7rwuXs6Xj1TsD8&app_code=4UXmaGFTe30LttFgOY7iqQ&searchtext=" + tbLoc.text;
// RUN THE ASYNCRONOUS COMMAND (I THINK)
StartCoroutine(GetText(url));
}
IEnumerator GetText(string url)
{
// CREATE WEB REQUEST WITH SPECIFIED URL
UnityWebRequest www = UnityWebRequest.Get(url);
// RETURN RESULTS FROM ASYNC COMMAND
yield return www.SendWebRequest();
// PARSE JSON RESPONSE
RootObject RootObject = JsonUtility.FromJson<RootObject>(www.downloadHandler.text);
// IF 200 (STATUS OKAY) GATHER RESULTS, ELSE RETURN ERROR
if (www.responseCode == 200)
{
BuildArray(RootObject);
}
else
{
Debug.Log("Call Failed With Error: " + www.responseCode.ToString());
}
}
private void BuildArray(RootObject RootObject)
{
print(RootObject.Response.View[0].Result[0].Location.Address.Label);
}
It attempts to run the BuildArray function but this returns a null reference. (I'm just using the NextPageInformation as the most basic option to test)
Below is the class structure I have built to deal with the JSON:
public class Address
{
public string Label { get; set; }
}
public class Location
{
public Address Address { get; set; }
}
public class Result
{
public Location Location { get; set; }
}
public class View
{
public List<Result> Result { get; set; }
}
public class Response
{
public List<View> View { get; set; }
}
public class RootObject
{
public Response Response { get; set; }
}
Can someone please help?
Thank you

If you want to parse only one key value pair from json then creating class structure will tedious job for you.
Instead of creating class structure you can Querying a json with Newtonsoft.
Parse your json.
Querying your parsed json to retrieve Label
value.
//1
JToken jToken = JToken.Parse(jsonString);
//2
string label = jToken["Response"]["View"][0]["Result"][0]["Location"]["Address"]["Label"].ToObject<string>();
Console.WriteLine(label);
Console.ReadLine();
Output: (from your sample json provided in link)
Note: You need to install newtonsoft.json package from nuget and add below namespace to your program.
using Newtonsoft.Json.Linq;
Edit:
If you want parsed your full json then first create a class structure like below
public class MetaInfo
{
public DateTime Timestamp { get; set; }
}
public class MatchQuality
{
public int City { get; set; }
public List<double> Street { get; set; }
public int HouseNumber { get; set; }
}
public class DisplayPosition
{
public double Latitude { get; set; }
public double Longitude { get; set; }
}
public class NavigationPosition
{
public double Latitude { get; set; }
public double Longitude { get; set; }
}
public class TopLeft
{
public double Latitude { get; set; }
public double Longitude { get; set; }
}
public class BottomRight
{
public double Latitude { get; set; }
public double Longitude { get; set; }
}
public class MapView
{
public TopLeft TopLeft { get; set; }
public BottomRight BottomRight { get; set; }
}
public class AdditionalData
{
public string value { get; set; }
public string key { get; set; }
}
public class Address
{
public string Label { get; set; }
public string Country { get; set; }
public string State { get; set; }
public string County { get; set; }
public string City { get; set; }
public string District { get; set; }
public string Street { get; set; }
public string HouseNumber { get; set; }
public string PostalCode { get; set; }
public List<AdditionalData> AdditionalData { get; set; }
}
public class Location
{
public string LocationId { get; set; }
public string LocationType { get; set; }
public DisplayPosition DisplayPosition { get; set; }
public List<NavigationPosition> NavigationPosition { get; set; }
public MapView MapView { get; set; }
public Address Address { get; set; }
}
public class Result
{
public int Relevance { get; set; }
public string MatchLevel { get; set; }
public MatchQuality MatchQuality { get; set; }
public string MatchType { get; set; }
public Location Location { get; set; }
}
public class View
{
public string _type { get; set; }
public int ViewId { get; set; }
public List<Result> Result { get; set; }
}
public class Response
{
public MetaInfo MetaInfo { get; set; }
public List<View> View { get; set; }
}
public class RootObject
{
public Response Response { get; set; }
}
And then you can deserialized your json like.
RootObject rootObject = JsonConvert.DeserializeObject<RootObject>(jsonString);
Note: You need to add below namespace to your program.
using Newtonsoft.Json;

I personally had problems parsing nested json objects with JsonUtility. So I switched to Newtonsoft Json and it works really well.
In your case you need to mark the classes as serialized using [Serializable] see here
[Serializable]
public class Address
{
public string Label;
}

Deserializing a nested JSON string, cannot access properties

I am having issues deserializing a nested JSON array from the Genius lyric website API. I formulated the object using http://json2csharp.com. When I deserialize the object, I am unable to access the properties inside of the class, which wasn't entirely unexpected, I am just not sure how to properly design an actual solution to the problem. The JSON object conversions work fine when they are not nested.
What would be the best way to go about handling this?
Here is the conversion code:
string test = await G.SearchGeniusASync(textBox1.Text);
var data = JsonConvert.DeserializeObject<GeniusApiObject>(test);
Here is my class:
class GeniusApiObject
{
public class Meta
{
public int status { get; set; }
}
public class Stats
{
public bool hot { get; set; }
public int unreviewed_annotations { get; set; }
public int concurrents { get; set; }
public int pageviews { get; set; }
}
public class PrimaryArtist
{
public string api_path { get; set; }
public string header_image_url { get; set; }
public int id { get; set; }
public string image_url { get; set; }
public bool is_meme_verified { get; set; }
public bool is_verified { get; set; }
public string name { get; set; }
public string url { get; set; }
public int iq { get; set; }
}
public class Result
{
public int annotation_count { get; set; }
public string api_path { get; set; }
public string full_title { get; set; }
public string header_image_thumbnail_url { get; set; }
public string header_image_url { get; set; }
public int id { get; set; }
public int lyrics_owner_id { get; set; }
public string lyrics_state { get; set; }
public string path { get; set; }
public int? pyongs_count { get; set; }
public string song_art_image_thumbnail_url { get; set; }
public Stats stats { get; set; }
public string title { get; set; }
public string title_with_featured { get; set; }
public string url { get; set; }
public PrimaryArtist primary_artist { get; set; }
}
public class Hit
{
public List<object> highlights { get; set; }
public string index { get; set; }
public string type { get; set; }
public Result result { get; set; }
}
public class Response
{
public List<Hit> hits { get; set; }
}
public class RootObject
{
public Meta meta { get; set; }
public Response response { get; set; }
}
}
This is the source for the SearchGeniusASync method in case it is helpful:
public async Task<string>SearchGeniusASync(string searchParameter)
{
httpClient.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", clientAccessToken);
var result = await httpClient.GetAsync(new Uri("https://api.genius.com/search?q=" + searchParameter), HttpCompletionOption.ResponseContentRead);
var data = await result.Content.ReadAsStringAsync();
return data;
}
This is the scope I am given access to:
https://i.imgur.com/9mZMvfp.png
Here's a sample JSON request in plaintext:
https://pastebin.com/iA8dQafW

GeniusApiObject is not needed in the code, but I'll leave it in just because it helps organize things (may be that something else also has a RootObject from the auto-generator).
The problem is that you are trying to deserialize to what is just an empty class, the class itself has no properties, so you can't deserialize to it. You need to deserialize to the GeniusApiObject.RootObject.
var data = JsonConvert.DeserializeObject<GeniusApiObject.RootObject>(test);
Will deserialize to the .RootObject subclass. This is verified working:
Where I'm using File.ReadAllText("test.json") to load the example API data provided.
Here is a .NET Fiddle showing it working (without the root object and only one song in the response). Thanks to #maccttura.

JSON.NET Resolving Nested Data Types

I'm new to JSON.NET, and I've been playing with the new Marvel API that was recently released.
When I call this API it will return the following JSON Data Structure:-
{
"code": 200,
"status": "Ok",
"etag": "f0fbae65eb2f8f28bdeea0a29be8749a4e67acb3",
"data":
{
"offset": 0,
"limit": 20,
"total": 30920,
"count": 20,
"results": [{array of objects}}]
}
}
I can create Classes for this Data like this :
public class Rootobject
{
public int code { get; set; }
public string status { get; set; }
public string etag { get; set; }
public Data data { get; set; }
}
public class Data
{
public int offset { get; set; }
public int limit { get; set; }
public int total { get; set; }
public int count { get; set; }
public Result[] results { get; set; }
}
public class Result
{
}
Now, my issue. The Results that come back from the API can relate to different Objects, it could be results relating to Characters, Comics, Series etc. The objects all hold different properties.
I need to be able to swap out the Result Class properties based on the Entity Type that the results relate too?
Can this actually be done?

You can use var jObj = JObject.Parse(jsonString) then discover what object type it is by which properties are available on the object.
jObj["someComicSpecificProperty"] != null
However this is not full proof and will need to be done on a per object basis for the results array.
An alternate approach I have seen people use is to have a property on the object that is "typeName".
However the root cause of this problem is that you are trying to strongly type a property that is not strongly typed. I would really recommend splitting these different types of results out into different properties so that you don't have this problem.

As promised, I've posted the anser to this problem. It turns out that the JSON response has nested data covering all related data-types, very much like a relational database.
I found something really cool, I basically made a request to the API and converted its response to a string. I then used the debugger to take a copy of the contents to the clipboard.
I created a new Class and Called it MarvelResponse.
I added the NewtonSoft.Json directive to the file, and used the Paste Special option from Edit Menu in VS2012. Here you can paste the option "Paste as JSON CLasses".
After some minor tweaking here is what it provided :-
namespace Kaiser.Training.Data.JSONClasses
{
public class MarvelResponse
{
public int code { get; set; }
public string status { get; set; }
public string etag { get; set; }
public Data data { get; set; }
}
public class Data
{
public int offset { get; set; }
public int limit { get; set; }
public int total { get; set; }
public int count { get; set; }
public Result[] results { get; set; }
}
public class Result
{
public int id { get; set; }
public string name { get; set; }
public string description { get; set; }
public DateTime modified { get; set; }
public Thumbnail thumbnail { get; set; }
public string resourceURI { get; set; }
public Comics comics { get; set; }
public Series series { get; set; }
public Stories stories { get; set; }
public Events events { get; set; }
public Url[] urls { get; set; }
}
public class Thumbnail
{
public string path { get; set; }
public string extension { get; set; }
}
public class Comics
{
public int available { get; set; }
public string collectionURI { get; set; }
public ComicResourceUriItem[] items { get; set; }
public int returned { get; set; }
}
public class ComicResourceUriItem
{
public string resourceURI { get; set; }
public string name { get; set; }
}
public class Series
{
public int available { get; set; }
public string collectionURI { get; set; }
public SeriesResourceItem[] items { get; set; }
public int returned { get; set; }
}
public class SeriesResourceItem
{
public string resourceURI { get; set; }
public string name { get; set; }
}
public class Stories
{
public int available { get; set; }
public string collectionURI { get; set; }
public StoriesResourceItem[] items { get; set; }
public int returned { get; set; }
}
public class StoriesResourceItem
{
public string resourceURI { get; set; }
public string name { get; set; }
public string type { get; set; }
}
public class Events
{
public int available { get; set; }
public string collectionURI { get; set; }
public EventsResourceUriItem[] items { get; set; }
public int returned { get; set; }
}
public class EventsResourceUriItem
{
public string resourceURI { get; set; }
public string name { get; set; }
}
public class Url
{
public string type { get; set; }
public string url { get; set; }
}
}
This was a huge help! Hope someone else finds it useful.