Develop Reference

C# Accessing APIs

I followed a tutorial (https://www.youtube.com/watch?v=aWePkE2ReGw) to try and call APIs using C#, and while it worked, my attempts to modify it for my own projects failed miserably. Despite my best efforts and trying various different links on the same website, they all return failure.
I was able to access it with python no problem, so the problem seems confined to C#. I have the microsoft.aspnet.webapi.client installed, as well as json. It compiles and runs, just returns failure.
https://dbd.tricky.lol/apidocs/
Here's the code:
namespace API_Test
{
// class used to initialize the httpclient
public class ApiHelper
{
public static HttpClient? ApiClient { get; set; }
public static void InitializeClient()
{
ApiClient = new HttpClient();
ApiClient.DefaultRequestHeaders.Accept.Clear();
ApiClient.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));
}
}
// used to hold the result
class ShrineModel
{
public double ID { get; set; }
}
// used for processing results
class ShrineResultModel
{
public ShrineModel? Results { get; set; }
}
// used to access the api
class ShrineProcessor
{
public static async Task<ShrineModel> LoadShrineInformation()
{
string url = "https://dbd.tricky.lol/api/shrine";
using (HttpResponseMessage response = await ApiHelper.ApiClient.GetAsync(url))
{
if (response.IsSuccessStatusCode)
{
ShrineResultModel result = await response.Content.ReadAsAsync<ShrineResultModel>();
return result.Results;
}
else
{
// ALWAYS ENDS UP HERE
Console.WriteLine("Failure");
Console.ReadKey();
throw new Exception(response.ReasonPhrase);
}
}
}
}
// main
public class API_Test
{
static async Task Main()
{
ApiHelper.InitializeClient();
var ShrineInfo = await ShrineProcessor.LoadShrineInformation();
Console.WriteLine(ShrineInfo.ID);
}
}
}
Best case scenario I get a json output with all the information found at the link. What I'm getting is a false response from "IsSuccessStatusCode"
I've tried various other endpoints available from the same website. Other APIs have worked. But I can't get this one to.

I ran your code against the API and there are a couple of issues to fix.
1. 403 Forbidden
You got response.IsSuccessStatusCode false because the API endpoint requires a User-Agent header. This is to block any web crawler bots.
To fix that you just need to add this code,
ApiClient.DefaultRequestHeaders.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; rv:91.0) Gecko/20100101 Firefox/91.0");
2. Wrong JSON data model
You must model the JSON response structure so the deserialization can work properly.
The JSON response:
{
"id": 666,
"perks": [
{
"id": "Aftercare",
"bloodpoints": 100000,
"shards": 2000
},
{
"id": "BeastOfPrey",
"bloodpoints": 100000,
"shards": 2000
},
{
"id": "DeadHard",
"bloodpoints": 100000,
"shards": 2000
},
{
"id": "Nemesis",
"bloodpoints": 100000,
"shards": 2000
}
],
"start": 1672185600,
"end": 1672790399
}
So your ShrineResultModel should be like this:
public class Perk
{
public string id { get; set; }
public int bloodpoints { get; set; }
public int shards { get; set; }
}
public class ShrineResultModel
{
public int id { get; set; }
public List<Perk> perks { get; set; }
public int start { get; set; }
public int end { get; set; }
}
Update your code to deserialize the JSON response:
if (response.IsSuccessStatusCode)
{
ShrineResultModel result = await response.Content.ReadFromJsonAsync<ShrineResultModel>();
return result;
}
The actual result:

Deserialize object into own type in C#

I am new to c# and I am willing to convert a Object into a class representing a User. I am retrieving the object from a http request to an API. My code is:
private async void getUser()
{
var requestURI = new HttpRequestMessage();
string url = "https:...";
requestURI.RequestUri = new Uri(url);
requestURI.Method = HttpMethod.Get;
requestURI.Headers.Add("Accept", "application/json");
HttpResponseMessage responseURI = await client.SendAsync(requestURI);
if (responseURI.StatusCode == HttpStatusCode.OK)
{
Debug.WriteLine("Get User OK");
var UserString = await responseURI.Content.ReadAsStringAsync();
Debug.WriteLine("User: " + UserString);
var UsersJson = JsonConvert.DeserializeObject(UsersString);
Debug.WriteLine(UserJson);
}
else
{
Debug.WriteLine("User GET request failed");
}
}
The output is:
{
"Username": "Alice",
"IP": "192.13.2.2",
"Levels": "1,2"
}
How do I create a class or a type to later deserealize this object into it? When the type/class is created, how do I deserealize the object into it?
Thanks in advice

You can use this website - https://json2csharp.com/ - to generate the C# classes.
In this case, the class would be as follows:
public class User
{
public string Username { get; set; }
public string IP { get; set; }
public string Levels { get; set; }
}
For deserialization to this class, you can use as follows:
var user = JsonConvert.DeserializeObject<User>(UsersString);

public class User
{
public string Username { get; set; }
public string IP { get; set; }
public string Levels { get; set; }
}
The you Deserialize an Object like this: Please have a look at this https://www.newtonsoft.com/json/help/html/SerializingJSON.htm
var user = JsonConvert.DeserializeObject<User>(json);

Add root element to response model

I'm writing an ASP.NET Core API, which should follow an existing format.
The response should always start with a data element in the json
{
"data": {
"batch_id": null,
"created_at": "2019-01-29T16:58:04+00:00",
"current_operation": null,
"description": "This watch has a new name",
"model": {
"brand_id": null,
"created_at": null,
...
}
}
}
I created a class Batch which contains all the properties that we see, and my controller is taking care of serialize it in the background.
public class Batch
{
[JsonProperty("label")]
public string Label { get; set; }
[JsonProperty("serial_number")]
public string SerialNumber { get; set; }
[HttpGet("{id}")]
public ActionResult<Batch> Get(string id)
{
...
return batch;
}
Is there a way to write something so that every payload has to start with a data property?
I would like to avoid writing a class DataWrapper<T> that I have to use for every response.

You could just use an anonymous object to wrap the response from the controller:
[HttpGet("{id}")]
public ActionResult<Batch> Get(string id)
{
...
return Ok(new { data = batch });
}

You can use GenericClass
public class GenericResponseClass<T>{
public T data;
}
then you can pass your batch(or any other) class to GenericResposneClass just like
public class Batch
{
[JsonProperty("label")]
public string Label { get; set; }
[JsonProperty("serial_number")]
public string SerialNumber { get; set; }
}
GenericResponseClass<Batch> response = new GenericResponseClass<Batch>();
Batch batch = new Batch();
batch.Label = "New Label";
batch.SerialNumber = "Serial Number";
response.data = batch;
then pass/serialize your response

JSON to derived types deserialization difficulties

i have a solution where i consume a WebService using RestSharp providing JSON data. I have a class model like this, matching the received data:
public class PBase
{
public string Name { get; set; }
public virtual string GetValue()
{
return string.Empty;
}
}
public class PDouble : PBase
{
public double DoubleValue { get; set; }
public string Scale { get; set; }
public override string GetValue()
{
return DoubleValue.ToString(CultureInfo.InvariantCulture);
}
}
public class PBool : PBase
{
public bool? BoolValue { get; set; }
public override string GetValue()
{
if (!BoolValue.HasValue)
return null;
return BoolValue.Value ? "1" : "0";
}
}
Meerely deep within the data, such blocks as the following appear multiple times, holding the parameters of a parent object, which is not of much interest here (as everything else except the parameter thingy works fine):
"Parameters":
[
{
"__type": "PDouble:http://name.space.de/Parameter",
"Name": "DEPTH",
"DoubleValue": 5,
"Scale": "MM"
},
{
"__type": "PDouble:http://name.space.de/Parameter",
"Name": "HEIGHT",
"DoubleValue": 10,
"Scale": "MM"
},
{
"__type": "PBool:http://name.space.de/Parameter",
"Name": "ESSENTIAL",
"BoolValue": true
},
]
Now, the problem is, the deserialized data contains only PBase instances. So everything except Name is gone. How can i achieve correct deserialization?
EDIT:
For deserialization i have nothing special implemented, just like this:
var client = new RestClient()
{
BaseUrl = new Uri("MyURL")
};
var request = new RestRequest()
{
Resource = "MyResource",
Method = Method.GET
};
request.AddHeader("Accept", "application/json");
request.RequestFormat = DataFormat.Json;
var response = client.Execute<MyType>(request);
return response.Data;

Cannot deserialize the current JSON array with metadata and records

Here is a sample of the JSON data I am getting back from a web service.
It has a single node of "odata.metadata", another single node of "value", and then the repeating records consisting of 3 fields "Code", "Name" and "XTag". This is in a string variable called Content
{"odata.metadata":"https://notthereal.domain:3148/system/OData/$metadata#pageLocationList","value":[{"Code":"LOC-A","Name":"Location A","XTag":"36;DgAAAAJ7/zEAMAAwAC0ATQBBAEkATgAAAAAA8;264943250;"},{"Code":"LOC-B","Name":"Location B","XTag":"36;DgAAAAJ7/zEAMAAxAC0ATQBBAEkATgAAAAAA8;388906690;"},{"Code":"LOC-C","Name":"Location C","XTag":"36;DgAAAAJ7/zEAMAAyAC0ATQBBAEkATgAAAAAA8;388844480;"},{"Code":"LOC-D","Name":"Location D","XTag":"36;DgAAAAJ7/zEAMAAzAC0ATQBBAEkATgAAAAAA8;388876720;"}]}
I have the following as the model, which I got by pasting the JSON data into the class.
public class ModelPageLocationList
{
public string odatametadata { get; set; }
public List<Value> value { get; set; }
}
public class Value
{
public string Code { get; set; }
public string Name { get; set; }
public string XTag { get; set; }
}
and this is the code trying to deserialise it...
DataPageLocationList =
JsonConvert.DeserializeObject<List<ModelPageLocationList>>(content);
..and this is the error message. I am stuck! Any ideas? I think the issue is around the 2 single records at the start, and then the repeating data after.
ERROR Cannot deserialize the current JSON object (e.g. {"name":"value"}) into type 'System.Collections.Generic.List because the type requires a JSON array (e.g. [1,2,3]) to deserialize correctly.
Here is what I am calling
public async Task<List<ModelPageLocationList>> RefreshPageLocationListAsync ()
{
DataPageLocationList = new List<ModelPageLocationList>();
var uri = new Uri(string.Format(WebServiceSettings.WebServiceUrl, string.Empty));
try
{
var response = await client.GetAsync(uri);
if (response.IsSuccessStatusCode)
{
var content = await response.Content.ReadAsStringAsync();
Debug.WriteLine("{0}", content.ToString());
DataPageLocationList = JsonConvert.DeserializeObject<List<ModelPageLocationList>>(content);
}
} catch (Exception ex)
{
Debug.WriteLine(#"ERROR {0}", ex.Message);
}
return (DataPageLocationList);
}

Two things. Use JsonProperty to handle the odata.metadata property as the dot (.) in the property name will cause syntax problems.
public class ModelPageLocationList {
[JsonProperty("odata.metadata")]
public string odatametadata { get; set; }
[JsonProperty("value")]
public List<Value> value { get; set; }
}
Next based on the provided JSON example data you need to refactor the calling code
public async Task<ModelPageLocationList> RefreshPageLocationListAsync () {
try {
var uri = new Uri(string.Format(WebServiceSettings.WebServiceUrl, string.Empty));
var response = await client.GetAsync(uri);
if (response.IsSuccessStatusCode) {
var result = await response.Content.ReadAsAsync<ModelPageLocationList>();
return result;
}
} catch (Exception ex) {
Debug.WriteLine(#"ERROR {0}", ex.Message);
}
return null;
}

You need to serialize to your root object ModelPageLocationList, NOT a list of your root objects. Your JSON is an object not an array of objects. This will fix it:
DataPageLocationList =
JsonConvert.DeserializeObject<ModelPageLocationList>(content);

Without seeing the JSON Data you are trying to pass in, I can only provide two possible answers based on the information you have provided.
1) Make sure your JSON Looks like this:
{
"odatametadata": "SomeDataHere",
"value": [{
"code": "Code1",
"name": "Name1",
"xTag": "XTag1"
}, {
"code": "Code1",
"name": "Name1",
"xTag": "XTag1"
}, {
"code": "Code1",
"name": "Name1",
"xTag": "XTag1"
},
]
}
2 Add this attribute to your C# Class Model
public class ModelPageLocationList
{
[JsonProperty("odatametadata")]
public string odatametadata { get; set; }
[JsonProperty("value")]
public List<Value> value { get; set; }
}
public class Value
{
[JsonProperty("code")]
public string Code { get; set; }
[JsonProperty("name")]
public string Name { get; set; }
[JsonProperty("xTag")]
public string XTag { get; set; }
}

I did the following to get my code to work with the JSON data at the start of my post. Not ideal, and I would prefer to be able to do this without having to edit the JSON string.
public async Task<List<ModelPageLocationList>> RefreshPageLocationListAsync ()
{
DataPageLocationList = new List<ModelPageLocationList>();
var uri = new Uri(string.Format(WebServiceSettings.WebServiceUrl, string.Empty));
try
{
var response = await client.GetAsync(uri);
if (response.IsSuccessStatusCode)
{
var content = await response.Content.ReadAsStringAsync();
Debug.WriteLine("BEFORE {0}", content.ToString());
content = content.Substring(content.IndexOf('['), content.IndexOf(']') - content.IndexOf('[') + 1);
Debug.WriteLine("AFTER {0}", content.ToString());
DataPageLocationList = JsonConvert.DeserializeObject<List<ModelPageLocationList>>(content);
}
}
catch (Exception ex)
{
Debug.WriteLine(#"ERROR {0}", ex.Message);
}
return (DataPageLocationList);
}
and the class from the JSON data
public class ModelPageLocationList
{
public string Code { get; set; }
public string Name { get; set; }
public string ETag { get; set; }
}
Thanks everyone for their replies.