Develop Reference

Mapping JSON from Yahoo! Finance API to C# objects [duplicate]

This question already has answers here:
Deserialize JSON data with C#
(4 answers)
Closed 1 year ago.
I am a student working on a project. I am trying to use the Yahoo! Finance API as a source for my data https://www.yahoofinanceapi.com . I can use HttpWebRequests to call the API and get the "OK" code, see the code below on how I did it:
string BaseURL = "https://yfapi.net/v6/finance/quote?symbols=AAPL";
string addSymbol = "%2C";
string URL = BaseURL;
foreach (string stock in stocks)
{
URL += addSymbol + stock;
}
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(URL);
request.Headers.Add("X-API-KEY", "[My API key]");
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Console.WriteLine(response.ContentType);
Console.WriteLine(response.StatusCode);
response.ContentType gives back "application/json".
response.StatusCode gives back "OK".
Since the response is a JSON I tried to parse it into a string using .ToString() but this obviously doesn't work. When I print it, it just says "System.Net.HttpWebResponse" instead of the showing the actual data in the JSON.
After that I tried to deserialize it using newtonsoft
Results result = JsonConvert.DeserializeObject<Results>(request.GetResponse().ToString());
where Results is a class I made where there is a list of stocks, Stock is also a class I made with some variables in it with the same names of variables in the JSON response.
I got a JSON response from PostMan when I tested the API, opened the response to see what kind of data it contained.
When I ran my code I got the following error message:
Newtonsoft.Json.JsonReaderException: 'Unexpected character encountered while parsing value: S. Path '', line 0, position 0.'
This was as far as I got, I tested a few other methods trying to get this working but this one worked the "best".
My biggest issue at the moment is mapping the response into a c# object.
Anything that can help me understand is appreciated :D

You're trying to serialise the HttpWebResponse object into Results, which means deserialisation won't work.
The data is still wrapped & won't be in the format of the Results object.
The GetResponseStream() method can be used to get the contents of the HTTP response as a stream, which can then be deserialised directly, in this case, using Json.NET.
Replace this section:
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Console.WriteLine(response.ContentType);
Console.WriteLine(response.StatusCode);
With this:
var serializer = new JsonSerializer();
using (var response = (HttpWebResponse)request.GetResponse())
{
var encoding = Encoding.GetEncoding(response.CharacterSet);
using var responseStream = response.GetResponseStream();
using var reader = new StreamReader(responseStream, encoding);
using (var jsonTextReader = new JsonTextReader(reader))
{
Console.WriteLine(response.ContentType);
Console.WriteLine(response.StatusCode);
Results result = serializer.Deserialize<Results>(jsonTextReader);
}
}
Alternatively, a much better solution if you're using .NET 4.5 <= would be to use HttpClient like below:
private static readonly HttpClient httpClient = new HttpClient();
...
string BaseURL = "https://yfapi.net/v6/finance/quote?symbols=AAPL";
string addSymbol = "%2C";
string URL = BaseURL;
foreach(string stock in stocks) {
URL += addSymbol + stock;
}
client.DefaultRequestHeaders.Add("X-API-KEY", "[My API key]");
var data = await httpClient.GetStringAsync(address);
Results result = JsonConvert.DeserializeObject<Results>(data);

Unable to deserialize JSON in C# using the same class at both ends

I'm looking for someone to point out the obvious blunder here.
A .NET Core in C# application makes an HTTP call to another such application. Some processing is performed, and a response is sent thus:
Response response = new Response(input)
{
stuff = processedStuff;
};
responseMessage = JsonConvert.SerializeObject(response);
return new OkObjectResult(responseMessage);
This all looks good and responseMessage contains valid JSON (according to an online JSON checker I found).
At the other end, this is received thus:
Response returned = new Response();
var response = await client.SendAsync(request);
if (response.IsSuccessStatusCode)
{
var json = await response.Content.ReadAsStringAsync();
returned = JsonConvert.DeserializeObject<Response>(json);
}
This fails with an Error converting value *the JSON string* to "Response" at line 1
Response is the same class file in both applications. What never obvious and apparently invisible mistake am I making here?

The invisible mistake you are making is double-serializing the result. The contract of OkObjectResult is that it will automatically serialize the result object to the negotiated content type (e.g. JSON or XML) and return an OK status. You are serializing the object first and then passing the serialized string to OkObjectResult so it ends up getting serialized twice.
responseMessage = JsonConvert.SerializeObject(response); // serialize to JSON
return new OkObjectResult(responseMessage); // implicit serialization here
Possible solutions:
Allow the implicit serialization to do its thing (recommended):
return new OkObjectResult(response); // implicit serialization of response object
Use a ContentResult instead (good if you need special serialization handling):
responseMessage = JsonConvert.SerializeObject(response); // serialize to JSON
return new ContentResult()
{
Content = responseMessage,
ContentType = "application/json",
StatusCode = 200
};
Deserialize twice on the receiving end (use as a last resort, i.e. you don't control the server):
var doubleSerializedJson = await response.Content.ReadAsStringAsync();
var json = JsonConvert.DeserializeObject<string>(doubleSerializedJson);
returned = JsonConvert.DeserializeObject<Response>(json);

check if the returned string is not wrapped in OkObjectResult object.

As far as I know, you don't need the serialization and deserialization, the framework already takes care of everything. If you need to, you could always deserialize to either an anonymous type or cast it from object.
https://www.newtonsoft.com/json/help/html/DeserializeAnonymousType.htm
I would also help if you could share the response class, since it's most likely part of the problem.

As someone old enough to remember when the Simpsons started, I can only answer in the traditional manner:
D'oh!
Using implicit serialization as described by the kind responder above resolved the issue.

Cannot serialize stream data asp .net core

Trying to deserialize objects from HTTP response.
Response stream returns information in json and I already checked if it is valid in online deserializer.
I got the object class from the API framework so I think all of the properties should be configured for the response.
Code:
var request = new HttpRequestMessage(HttpMethod.Get,
"api_url");
var client = _clientFactory.CreateClient();
var response = await client.SendAsync(request);
if (response.IsSuccessStatusCode)
{
using var responseStream = await response.Content.ReadAsStreamAsync();
var reponseString = await response.Content.ReadAsStringAsync();
var data = await JsonSerializer.DeserializeAsync<IEnumerable<Tournament>>(responseStream);
}
else
{
GetBranchesError = true;
}
I see that information in responseString is correct but data objects are always null.
Weird part is that it partially works because it shows how many objects are in the responseStream but all of the object properties are nulls.
Also tried to set the stream position to 0 - didn't help.
Any idea what I am doing wrong to deserialize these objects?
Desirializer used - System.Text.Json;
Project asp .net core 3.1

The problem is that the properties you are looking for in the JSON array are actually wrapped inside an object called "tournament". It's easier to notice when you format the JSON string nicely like this for example:
[
{
"tournament": {
"id": 1,
"name": "name1",
...
}
},
{
"tournament": {
"id": 2,
"name": "name2",
...
}
}
]
To deserialize this I would suggest you make a wrapper class to handle that:
public class TournamentItem
{
[JsonPropertyName("tournament")]
public Tournament Tournament { get; set; }
}
And then deserialize to that class:
var data = await JsonSerializer.DeserializeAsync<IEnumerable<TournamentItem>>(responseStream);
Now data.Tournament will contain all the properties.
There might still be a few issues in your properties like Spam for example. The JSON string has a null as value, but the property is not nullable - I didn't check all your properties. DeserializeAsync will throw an error and tell you.

Parse JSON response where the object starts with a number in c#

I'm trying to deserialise a response from a REST service into C# Strongly typed classes - however I've ran into the same issue has in this post:
How do I output this JSON value where the key starts with a number?
However I have the issue that you cannot start a variable name in c# with a number - meaning that the class at that level just deserialises into null.
I need to know how to get into the objects and deserialise them into the c# classes.
My Current code is below:
public static async Task<T> MakeAPIGetRequest<T>(string uri)
{
Uri requestURI = new Uri(uri);
using (HttpClient client = new HttpClient())
{
HttpResponseMessage responseGet = await client.GetAsync(requestURI);
if (responseGet.StatusCode != HttpStatusCode.OK)
{
throw new Exception(String.Format(
"Server error (HTTP {0}: {1}).",
responseGet.StatusCode,
responseGet.Content));
}
else
{
string response = await responseGet.Content.ReadAsStringAsync();
T objects = (JsonConvert.DeserializeObject<T>(response));
return objects;
}
}
}
EDIT: I cannot change the way the service is pushing the data back

The correct way to deal with this was to use the JsonProperty tag on the target classes to define what Json property to listen for, as shown below (referenced from https://stackoverflow.com/questions/24218536/deserialize-json-that-has-some-property-name-starting-with-a-number
public class MyClass
{
[JsonProperty(PropertyName = "24hhigh")]
public string Highest { get; set; }
...
Thanks to #HebeleHododo for the comment answer

While there is no direct way to construct a strongly typed C# object in this case, You could still have the capabilities to parse the json string manually and extract values -
var json = "{'1':{'name':'test','age':'test'}}";
var t = JObject.Parse(json)["1"];
Console.WriteLine(t["name"]); //test
Console.WriteLine(t["age"]); //test

Deserializing the object inside an http post

Hi I am trying to deserialize an Object from a HttpPost method call inside an authorize attribute.I am using ASP.NET Web Api Framework.
Here is my code:
public override void OnAuthorization(HttpActionContext actionContext)
{
var rezult = DeserializeStream<EvaluationFormDataContract>(actionContext.Request.Content.ReadAsStreamAsync().Result);
}
private T DeserializeStream<T>(Stream stream)
{
var binaryFormatter = new BinaryFormatter();
var rez = binaryFormatter.Deserialize(stream);
var t = (T)binaryFormatter.Deserialize(stream);
return t;
}
When this code gets executed I get this exception when the binaryFormatter tryes to deserialize it:
The input stream is not a valid binary format. The starting contents (in bytes) are: 73-74-75-64-65-6E-74-41-73-73-69-67-6E-6D-65-6E-74 ...
What am I doing wrong?

You are trying to use BinaryFormatter to binary deserialize data which was not binary serialized. From data you sent I see that hex code represents a string.
73-74-75-64-65-6E-74-41-73-73-69-67-6E-6D-65-6E-74 decoded is studentAssignment
This leads me to believe you are doing a simple AJAX call and sending JSON data to WebAPI service.
You need to deserialize the stream using JSON.
Read request content as string
If content is JSON, deserialize it using JSON.NET
var json = actionContext.Request.Content.ReadAsStringAsync().Result;
var m = JsonConvert.DeserializeObject<EvaluationFormDataContract>(json);
If response is not JSON, but form data you can parse it like a query string.
var stringData = actionContext.Request.Content.ReadAsStringAsync().Result;
NameValueCollection data = HttpUtility.ParseQueryString(stringData);
string personId = data["personId"];