Develop Reference

Error converting JSON response from backend to type with JsonConvert.DeserializeObject

So I am having this weird problem with deserializing a response from my BackEnd, The request works fine and the BackEnd succesfully responds with a result.
This is the error I get:
'Error converting value "{"Succes":true,"AuthKey":"$2a$13..."}" to type 'FrontEnd.LoginUserResponse'. Path '', line 1, position 96.'
The code I am using to make the HTTP call and deserialize the string:
public async Task<bool> loginUser(LoginUserData login)
{
HttpContent httpContent = new StringContent(JsonConvert.SerializeObject(login), Encoding.UTF8);
httpContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");
HttpResponseMessage responseMessage = await httpClient.PostAsync("http://ip/webBackEnd/api/user/login", httpContent);
string response2 = responseMessage.Content.ReadAsStringAsync().Result;
LoginUserResponse response = JsonConvert.DeserializeObject<LoginUserResponse>(response2);
if (response.Succes)
{
return true;
}
else { return false; }
}
I tried making a response2 to check the value and I have noticed it does something weird with 3 backslashes. This might be the reason why this is occuring.
This is response2 that visual studio shows when I click the magnifying glass:
"{\"Succes\":true,\"AuthKey\":\"$2a$11$tQCw4zGGd2J2fXAxAN68Ruu3xheTuMKq4EHbeLtc9DAa2rgzJe8bS\"}"
When I hover on visual studio:
https://imgur.com/a/jUyLz6d
This is the Class that it is converting to
public class LoginUserResponse
{
[JsonProperty("succes")]
public bool succes { get; set; }
[JsonProperty("authkey")]
public string authkey { get; set; }
}
The Backend code:
[HttpPost]
[Route("login")]
public string Login([FromBody]LogInData logInData)
{
IReadUser.LogInRequest request = new IReadUser.LogInRequest(logInData);
IReadUser.LogInResponse backResponse = readUser.logIn(request);
LogInResponse response = new LogInResponse();
response.succes = backResponse.Succes;
response.authkey = backResponse.AuthKey;
return JsonConvert.SerializeObject(response);
}
EDIT // SOLUTION
Ok so, the front-end was fine, it was my backend code sending a double serialised string. I used
return JsonConvert.SerializeObject(response);
When I also could have used
return response;
So if you every get an error like this, it's probably the backend doubling up on the serialization.
Thanks for all the help!

Couple of things:
1. you should await responseMessage.Content.ReadAsStringAsync():
public async Task<bool> loginUser(LoginUserData login)
{
var httpContent = new StringContent(JsonConvert.SerializeObject(login), Encoding.UTF8);
httpContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");
var responseMessage = await httpClient.PostAsync("http://ip/webBackEnd/api/user/login", httpContent);
var response2 = await responseMessage.Content.ReadAsStringAsync();
var response = JsonConvert.DeserializeObject<LoginUserResponse>(response2);
return response.Succes
}
And 2. Based on your image it looks like the response from your backing service is being serialized twice.
1:
"{\"Succes\":true,\"AuthKey\":\"$2a$11$tQCw4zGGd2J2fXAxAN68Ruu3xheTuMKq4EHbeLtc9DAa2rgzJe8bS\"}"
2:
"\"{\\\"Succes\\\":true,\\\"AuthKey\\\":\\\"$2a$11$tQCw4zGGd2J2fXAxAN68Ruu3xheTuMKq4EHbeLtc9DAa2rgzJe8bS\\\"}\""
now to deserialize you have to do it twice
var s = JsonConvert.DeserializeObject<string>(response2);
var response = JsonConvert.DeserializeObject<LoginUserResponse>(s);
Probably best to fix the service if that's actually what is happening

Consuming WEB API using HttpClient in c# console application

I have created a web API in visual studio 2015 using a MySQL database. The API is working perfect.
So I decided to make a console client application in which I can consume my web-service (web API). The client code is based on HttpClient, and in the API I have used HttpResponse. Now when I run my console application code, I get nothing. Below is my code:
Class
class meters_info_dev
{
public int id { get; set; }
public string meter_msn { get; set; }
public string meter_kwh { get; set; }
}
This class is same as in my web API model class:
Model in web API
namespace WebServiceMySQL.Models
{
using System;
using System.Collections.Generic;
public partial class meters_info_dev
{
public int id { get; set; }
public string meter_msn { get; set; }
public string meter_kwh { get; set; }
}
Console application code
static HttpClient client = new HttpClient();
static void ShowAllProducts(meters_info_dev mi)
{
Console.WriteLine($"Meter Serial Number:{mi.meter_msn}\t Meter_kwh: {mi.meter_kwh}", "\n");
}
static async Task<List<meters_info_dev>> GetAllRecordsAsync(string path)
{
List<meters_info_dev> mID = new List<meters_info_dev>();
HttpResponseMessage response = await client.GetAsync(path);
if (response.IsSuccessStatusCode)
{
mID = await response.Content.ReadAsAsync<List<meters_info_dev>>();
}
else
{
Console.WriteLine("No Record Found");
}
return mID;
}
static void Main()
{
RunAsync().Wait();
}
static async Task RunAsync()
{
client.BaseAddress = new Uri("http://localhost:2813/");
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
var m = await GetAllRecordsAsync("api/metersinfo/");
foreach(var b in m)
{
ShowAllProducts(b);
}
}
In my API I have 3 GET methods under a single controller, so I have created different routes for them. Also the URL for them is different.
http://localhost:2813/api/metersinfo/ will return all records
While debugging the code, I found that List<meters_info_dev> mID = new List<meters_info_dev>(); is empty:
While the response is 302 Found, the URL is also correct:
Update 1
After a suggestion I have done the following:
using (var client = new HttpClient())
{
List<meters_info_dev> mID = new List<meters_info_dev>();
HttpResponseMessage response = await client.GetAsync(path);
if (response.IsSuccessStatusCode)
{
mID = await response.Content.ReadAsAsync<List<meters_info_dev>>();
}
else
{
Console.WriteLine("No Record Found");
}
return mID;
}
When I run the application, I get the exception "An invalid request URI was provided. The request URI must either be an absolute URI or BaseAddress must be set."
Update 2
I have added a new piece of code:
using (var cl = new HttpClient())
{
var res = await cl.GetAsync("http://localhost:2813/api/metersinfo");
var resp = await res.Content.ReadAsStringAsync();
}
And in the response I am getting all the records:
I don't know why it's not working with the other logic and what the problem is. I have also read the questions Httpclient consume web api via console app C# and Consuming Api in Console Application.
Any help would be highly appreciated.

The code needs quite a bit of work.
The line you highlighted will always be empty because that's where you initialise the variable. What you want is run thorugh the code until you get the result back form the call.
First, make sure your api actually works, you can call the GET method you want in the browser and you see results.
using (var client = new HttpClient())
{
var result = await client.GetAsync("bla");
return await result.Content.ReadAsStringAsync();
}
that's an example of course, so replace that with your particular data and methods.
now, when you check the results just because your response.IsSuccessStatusCode is false that doesn't mean there are no records. What it means is that the call failed completely. Success result with an empty list is not the same thing as complete failure.
If you want to see what you get back you can alter your code a little bit:
if(response.IsSuccessStatusCode)
{
var responseData = await response.Content.ReadAsStringAsync();
//more stuff
}
put a breakpoint on this line and see what you actually get back, then you worry about casting the result to your list of objects. Just make sure you get back the same thing you get when you test the call in the browser.
<------------------------------->
More details after edit.
Why don't you simplify your code a little bit.
for example just set the URL of the request in one go :
using (var client = new HttpClient())
{
var result = await client.GetAsync("http://localhost:2813/api/metersinfo");
var response = await result.Content.ReadAsStringAsync();
//set debug point here and check to see if you get the correct data in the response object
}
Your first order of the day is to see if you can hit the url and get the data.
You can worry about the base address once you get a correct response. Start simple and work your way up from there, once you have a working sample.
<----------------- new edit ---------------->
Ok, now that you are getting a response back, you can serialise the string back to the list of objects using something like Newtonsoft.Json. This is a NuGet package, you might either have it already installed, if not just add it.
Add a using statement at the top of the file.
using Newtonsoft.Json;
then your code becomes something like :
using (var client = new HttpClient())
{
var result = await client.GetAsync("bla");
var response = await result.Content.ReadAsStringAsync();
var mID = JsonConvert.DeserializeObject<List<meters_info_dev>>(response);
}
At this point you should have your list of objects and you can do whatever else you need.

Getting "An action can only be invoked as a 'POST' request" when I am trying to call outlook restful api

Currently working with the outlook api, even tough I usually work with the outlook library acquired via Nuget; I have reached a limitation where I am not able to accept event invitations. So I proceeded in making a a restful call out to the the outlook api. However, when I am making the call I am getting the following message {"error":{"code":"InvalidMethod","message":"An action can only be invoked as a 'POST' request."}} when executing the call.
Bad Code
class Program
{
static void Main(string[] args)
{
var testAccept = ExecuteClientCall.AcceptEvent().Result;
}
public static async Task<bool> AcceptEvent()
{
AuthenticationContext authenticationContext = new AuthenticationContext(CrmPrototype.Helpers.AuthHelper.devTenant);
try
{
var token = await GetTokenHelperAsync(authenticationContext, CrmPrototype.Helpers.AuthHelper.OutlookAuthenticationEndpoint);
string requestUrl = "https://outlook.office.com/api/v2.0/Users/***#nowwhere.com/events('AAQkAGZiNDQxZTVkLWQzZjEtNDdjNy04OTc4LTM4NmNjM2JiOTRjNAAQAFpV0CnWR0FIpWFYRtszPHU=')/accept";
HttpClient hc = new HttpClient();
hc.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", token);
var method = new HttpMethod("POST");
var request = new HttpRequestMessage(method, requestUrl)
{
Content = new StringContent("{SendResponse: true}", Encoding.UTF8, "application/json")
};
HttpResponseMessage hrm = await hc.GetAsync(requestUrl);
if (hrm.IsSuccessStatusCode)
{
string jsonresult = await hrm.Content.ReadAsStringAsync();
var stophere = 0;
}
else
{
return false;
}
return true;
}
catch (Exception ex)
{
throw;
}
}
}

Maybe the reason is that you called
hc.GetAsync(requestUrl);
The doc said that this method:
Sends a GET request to the specified Uri as an asynchronous operation.
Try:
PostAsync(Uri, HttpContent)
https://msdn.microsoft.com/en-us/library/system.net.http.httpclient(v=vs.118).aspx
Hope this help you.

Your variable request contains an HttpRequestMessage object that you have created, but your code presently doesn't do anything with it.
Try replacing the line
HttpResponseMessage hrm = await hc.GetAsync(requestUrl);
(which, as pointed out by the other answer, makes a GET request), with
HttpResponseMessage hrm = await hc.SendAsync(request);

How can I get JSON data from Google API and store it in a variable?

I am trying to send an Http Get message to the Google location Api which is supposed to have Json data such as this
https://maps.googleapis.com/maps/api/geocode/json?address=Los%20Angeles,CA=AIzaSyDABt
as you noticed the response is in Json. I want to give a a Http Call to that URL and save the Json content in a variable or string. My code does not give out any errors but it is also not returning anything
public async System.Threading.Tasks.Task<ActionResult> GetRequest()
{
var client = new HttpClient();
HttpResponseMessage response = await client.GetAsync("https://maps.googleapis.com/maps/api/geocode/json?address=Los%20Angeles,CA=AIzaSyDABt");
string data = response.Content.ToString();
return data;
}
I want to send out a Get Request using HttpClient() or anything that will send out the URL request and then save that content into a string variable . Any suggestions would be appreciated, again my code gives no errors but it is not returning anything.

Use ReadAsStringAsync to get the json response...
static void Main(string[] args)
{
HttpClient client = new HttpClient();
Task.Run(async () =>
{
HttpResponseMessage response = await client.GetAsync("https://maps.googleapis.com/maps/api/geocode/json?address=Los%20Angeles,CA=AIzaSyDABt");
string responseString = await response.Content.ReadAsStringAsync();
Console.WriteLine(responseString);
});
Console.ReadLine();
}
If you use response.Content.ToString() it is actually converting the datatype of the Content to string so you will get System.Net.Http.StreamContent

Try this.
var client = new HttpClient();
HttpResponseMessage httpResponse = await client.GetAsync("https://maps.googleapis.com/maps/api/geocode/json?address=Los%20Angeles,CA=AIzaSyDABt");
string data = await httpResponse.Content.ReadAsStringAsync();

How about using the Json framework for .NET powered by Newtonsoft ?
You can try to parse your content to a string with this.

Well, your code can be simplified:
public async Task<ActionResult> GetRequest()
{
var client = new HttpClient();
return await client.GetStringAsync("https://maps.googleapis.com/maps/api/geocode/json?address=Los%20Angeles,CA=AIzaSyDABt");
}
However...
My code does not give out any errors but it is also not returning anything
This is almost certainly due to using Result or Wait further up the call stack. Blocking on asynchronous code like that causes a deadlock that I explain in full on my blog. The short version is that there is an ASP.NET request context that only permits one thread at a time; await by default will capture the current context and resume in that context; and since Wait/Result is blocking a thread in the request context, the await cannot resume executing.

Try this
public async static Task<string> Something()
{
var http = new HttpClient();
var url = "https://maps.googleapis.com/maps/api/geocode/json?address=Los%20Angeles,CA=AIzaSyDABt";
var response = await http.GetAsync(url);
if (response.IsSuccessStatusCode)
{
var result = await response.Content.ReadAsStringAsync();
result = JsonConvert.DeserializeObject<string>(result);
return result;
}
return "";
}
var result = Task.Run(() => Something()).Result;

.NET HttpClient hangs when using await keyword?

After considering this interesting answer HttpClient.GetAsync(...) never returns..., I still have a situation where my HttpClient is not returning when I use await (sample code below). In addition. I use this helper routine from both asp.net MVC5 Controllers (UI-driven) and the WebApi. What can I do to:
Use await instead of the (dreaded) .Result and still have this function return?
Reuse this same routine from both MVC Controllers and WebApi?
Apparently, I should replace the .Result with .ConfigureAwait(false) but this seems to contradict with the fact that "Task4" in the post cited above works fine with an await httpClient.GetAsync. Or do I need separate routines for Controller and WebApi cases?
public static async Task<IEnumerable<TcMarketUserFullV1>> TcSearchMultiUsersAsync(string elasticQuery)
{
if (string.IsNullOrEmpty(elasticQuery)) return null;
IEnumerable<TcMarketUserFullV1> res = null;
using (var hclient = new HttpClient())
{
hclient.BaseAddress = new Uri("https://addr.servicex.com");
hclient.DefaultRequestHeaders.Accept.Clear();
hclient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
hclient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer",
CloudConfigurationManager.GetSetting("jwt-bearer-token"));
// Why does this never return when await is used?
HttpResponseMessage response = hclient.GetAsync("api/v2/users?q=" + elasticQuery + "&search_engine=v2").Result;
if (response.IsSuccessStatusCode)
{
var content = await response.Content.ReadAsStringAsync();
res = JsonConvert.DeserializeObject<TcMarketUserFullV1[]>(content).AsEnumerable();
}
else{log.Warn("...");}
}
return res;
}
UPDATE: My call chain, which starts with a Telerik Kendo Mvc.Grid DataBinding call is as follows:
[HttpPost]
public async Task<ActionResult> TopLicenseGrid_Read([DataSourceRequest]DataSourceRequest request)
{
var res = await GetLicenseInfo();
return Json(res.ToDataSourceResult(request)); // Kendo.Mvc.Extensions.DataSourceRequest
}
Then:
private async Task<IEnumerable<CsoPortalLicenseInfoModel>> GetLicenseInfo()
{
...
// Never returns
var qry = #"app_metadata.tc_app_user.country:""DE""";
return await TcSearchMultiUsersAsync(qry);
}
Then, the routine shown in full above but now WITHOUT the .Result:
public static async Task<IEnumerable<TcMarketUserFullV1>> TcSearchMultiUsersAsync(string elasticQuery)
{
if (string.IsNullOrEmpty(elasticQuery)) return null;
IEnumerable<TcMarketUserFullV1> res = null;
using (var hclient = new HttpClient())
{
hclient.BaseAddress = new Uri("https://addr.servicex.com");
hclient.DefaultRequestHeaders.Accept.Clear();
hclient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
hclient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer",
CloudConfigurationManager.GetSetting("jwt-bearer-token"));
// This now returns fine
HttpResponseMessage response = hclient.GetAsync("api/v2/users?search_engine=v2&q=" + elasticQuery");
if (response.IsSuccessStatusCode)
{
// This returns my results fine too
var content = await response.Content.ReadAsStringAsync();
// The following line never returns results. When debugging, everything flows perfectly until I reach the following line, which never
// returns and the debugger returns me immediately to the top level HttpPost with a result of null.
res = JsonConvert.DeserializeObject<TcMarketUserFullV1[]>(content).AsEnumerable();
}
else{log.Warn("...");}
}
return res;
}

You need to await everything. It's not enough that you await on one of them, you need to await on all of them:
This:
HttpResponseMessage response = hclient.GetAsync(
"api/v2/users?q=" + elasticQuery + "&search_engine=v2").Result;
Should be:
HttpResponseMessage response = await hclient.GetAsync(
"api/v2/users?q=" + elasticQuery + "&search_engine=v2");
It is enough to have one blocking call to .Result in order to deadlock. You need "async all the way".