Develop Reference

How can I add a query string into HttpClient.BaseAdress in c#?

I'm trying to pass a query string into a BaseAddress but it doesn't recognize the quotation mark "?".
The quotation breaks the URI
First I create my BaseAddress
httpClient.BaseAddress = new Uri($"https://api.openweathermap.org/data/2.5/weather?appid={Key}/");
Then I call the GetAsync method, trying to add another parameter
using (var response = await ApiHelper.httpClient.GetAsync("&q=mexico"))....
This is the URI the code is calling
https://api.openweathermap.org/data/2.5/&q=mexico

I'd be tempted to use a DelegatingHandler if you need to apply an API key to every single request:
private class KeyHandler : DelegatingHandler
{
private readonly string _escapedKey;
public KeyHandler(string key) : this(new HttpClientHandler(), key)
{
}
public KeyHandler(HttpMessageHandler innerHandler, string key) : base(innerHandler)
{
// escape the key since it might contain invalid characters
_escapedKey = Uri.EscapeDataString(key);
}
protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
// we'll use the UriBuilder to parse and modify the url
var uriBuilder = new UriBuilder(request.RequestUri);
// when the query string is empty, we simply want to set the appid query parameter
if (string.IsNullOrEmpty(uriBuilder.Query))
{
uriBuilder.Query = $"appid={_escapedKey}";
}
// otherwise we want to append it
else
{
uriBuilder.Query = $"{uriBuilder.Query}&appid={_escapedKey}";
}
// replace the uri in the request object
request.RequestUri = uriBuilder.Uri;
// make the request as normal
return base.SendAsync(request, cancellationToken);
}
}
Usage:
httpClient = new HttpClient(new KeyHandler(Key));
httpClient.BaseAddress = new Uri($"https://api.openweathermap.org/data/2.5/weather");
// since the logic of adding/appending the appid is done based on what's in
// the query string, you can simply write `?q=mexico` here, instead of `&q=mexico`
using (var response = await ApiHelper.httpClient.GetAsync("?q=mexico"))
** Note: If you're using ASP.NET Core, you should call services.AddHttpClient() and then use IHttpHandlerFactory to generate the inner handler for KeyHandler.

This is how I work around it:
Http client impl:
namespace StocksApi2.httpClients
{
public interface IAlphavantageClient
{
Task<string> GetSymboleDetailes(string queryToAppend);
}
public class AlphavantageClient : IAlphavantageClient
{
private readonly HttpClient _client;
public AlphavantageClient(HttpClient httpClient)
{
httpClient.BaseAddress = new Uri("https://www.alphavantage.co/query?apikey=<REPLACE WITH YOUR TOKEN>&");
httpClient.DefaultRequestHeaders.Add("Accept", "application/json; charset=utf-8");
httpClient.DefaultRequestHeaders.Add("User-Agent", "HttpClientFactory-Sample");
_client = httpClient;
}
public async Task<string> GetSymboleDetailes(string queryToAppend)
{
_client.BaseAddress = new Uri(_client.BaseAddress + queryToAppend);
return await _client.GetStringAsync("");
}
}
}
Controller:
namespace StocksApi2.Controllers
{
[ApiController]
[Route("api/[controller]")]
public class SymbolDetailsController : ControllerBase
{
private readonly IAlphavantageClient _client;
public SymbolDetailsController(IAlphavantageClient client)
{
_client = client;
}
[HttpGet]
public async Task<ActionResult> Get([FromQuery]string function = "TIME_SERIES_INTRADAY",
[FromQuery]string symbol = "MSFT", [FromQuery]string interval = "5min")
{
try {
string query = $"function={function}&symbol={symbol}&interval={interval}";
string result = await _client.GetSymboleDetailes(query);
return Ok(result);
}catch(Exception e)
{
return NotFound("Error: " + e);
}
}
}
}
And in Startup.cs inside ConfigureServices:
services.AddHttpClient();
services.AddHttpClient<IAlphavantageClient, AlphavantageClient>();

Add multiple tokens into DefaultRequestHeaders.Authorization in HttpClient

The API I'm calling from my ASP.NET Web API app requires two tokens i.e. accessToken and userToken.
The following code is not working because it takes only the second token, not both. Looks like the second line is over-writing the first one.
How do I add multiple tokens to my request header?
_client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("APIAccessToken", "token1");
_client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("UserToken", "token2");
UPDATE:
Here's the way I set this up and it's not working. Basically, my API calls seem to go nowhere. I get no errors. Just no response.
First, I have the HttpClientAccessor that looks like this:
public static class HttpClientAccessor
{
private static Lazy<HttpClient> client = new Lazy<HttpClient>(() => new HttpClient());
public static HttpClient HttpClient
{
get
{
client.Value.BaseAddress = new Uri("https://api.someurl.com");
client.Value.DefaultRequestHeaders.Accept.Clear();
client.Value.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
client.Value.DefaultRequestHeaders.TryAddWithoutValidation("APIAccessToken", "token1");
client.Value.DefaultRequestHeaders.TryAddWithoutValidation("UserToken", "token2");
return client.Value;
}
}
}
I then have my ApiClient that will perform my API calls which looks like this:
public class MyApiClient
{
HttpClient _client;
public MyApiClient()
{
_client = HttpClientAccessor.HttpClient;
}
public async Task Get()
{
try
{
HttpResponseMessage response = await _client.GetAsync("/myendpoint"); // This is where it gets lost
var data = await response.Content.ReadAsStringAsync();
}
catch(Exception e)
{
var error = e.Message;
}
}
}
This is my controller action:
public class MyController : Controller
{
private readonly MyApiClient _client;
public MyController()
{
_client = new MyApiClient();
}
public IActionResult SomeAction()
{
_client.Get().Wait();
}
}

You are confusing the standard authorization header with custom headers
According to the linked documentation
Request Header
Add the generated tokens to the request headers "APIAccessToken" and "UserToken"
Example Request
APIAccessToken: zjhVgRIvcZItU8sCNjLn+0V56bJR8UOKOTDYeLTa43eQX9eynX90QntWtINDjLaRjAyOPgrWdrGK12xPaOdDZQ==
UserToken: 5sb8Wf94B0g3n4RGOqkBdPfX+wr2pmBTegIK73S3h7uL8EzU6cjsnJ0+B6vt5iqn0q+jkZgN+gMRU4Y5+2AaXw==
To get headers like above, add them to the client like below
_client.DefaultRequestHeaders.TryAddWithoutValidation("APIAccessToken", "token1");
_client.DefaultRequestHeaders.TryAddWithoutValidation("UserToken", "token2");
Based on shown update, the client is adding the headers every time the client is called. This should be in the value factory of the lazy client.
public static class HttpClientAccessor {
public static Func<HttpClient> ValueFactory = () => {
var client = new HttpClient();
client.BaseAddress = new Uri("https://someApiUrl");
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
client.DefaultRequestHeaders.TryAddWithoutValidation("APIAccessToken", "token1");
client.DefaultRequestHeaders.TryAddWithoutValidation("UserToken", "token2");
return client;
};
private static Lazy<HttpClient> client = new Lazy<HttpClient>(ValueFactory);
public static HttpClient HttpClient {
get {
return client.Value;
}
}
}
The controller action also needs to be refactored to avoid deadlocks because of the mixing of async and blocking calls like .Wait() or .Result.
public class MyController : Controller {
private readonly MyApiClient _client;
public MyController() {
_client = new MyApiClient();
}
public async Task<IActionResult> SomeAction() {
await _client.Get();
//... code removed for brevity
}
}

WebAPi - unify error messages format from ApiController and OAuthAuthorizationServerProvider

In my WebAPI project I'm using Owin.Security.OAuth to add JWT authentication.
Inside GrantResourceOwnerCredentials of my OAuthProvider I'm setting errors using below line:
context.SetError("invalid_grant", "Account locked.");
this is returned to client as:
{
"error": "invalid_grant",
"error_description": "Account locked."
}
after user gets authenticated and he tries to do "normal" request to one of my controllers he gets below response when model is invalid (using FluentValidation):
{
"message": "The request is invalid.",
"modelState": {
"client.Email": [
"Email is not valid."
],
"client.Password": [
"Password is required."
]
}
}
Both requests are returning 400 Bad Request, but sometimes You must look for error_description field and sometimes for message
I was able to create custom response message, but this only applies to results I'm returning.
My question is: is it possible to replace message with error in response that is returned by ModelValidatorProviders and in other places?
I've read about ExceptionFilterAttribute but I don't know if this is a good place to start. FluentValidation shouldn't be a problem, because all it does is adding errors to ModelState.
EDIT:
Next thing I'm trying to fix is inconsistent naming convention in returned data across WebApi - when returning error from OAuthProvider we have error_details, but when returning BadRequest with ModelState (from ApiController) we have modelState. As You can see first uses snake_case and second camelCase.

UPDATED ANSWER (Use Middleware)
Since the Web API original delegating handler idea meant that it would not be early enough in the pipeline as the OAuth middleware then a custom middleware needs to be created...
public static class ErrorMessageFormatter {
public static IAppBuilder UseCommonErrorResponse(this IAppBuilder app) {
app.Use<JsonErrorFormatter>();
return app;
}
public class JsonErrorFormatter : OwinMiddleware {
public JsonErrorFormatter(OwinMiddleware next)
: base(next) {
}
public override async Task Invoke(IOwinContext context) {
var owinRequest = context.Request;
var owinResponse = context.Response;
//buffer the response stream for later
var owinResponseStream = owinResponse.Body;
//buffer the response stream in order to intercept downstream writes
using (var responseBuffer = new MemoryStream()) {
//assign the buffer to the resonse body
owinResponse.Body = responseBuffer;
await Next.Invoke(context);
//reset body
owinResponse.Body = owinResponseStream;
if (responseBuffer.CanSeek && responseBuffer.Length > 0 && responseBuffer.Position > 0) {
//reset buffer to read its content
responseBuffer.Seek(0, SeekOrigin.Begin);
}
if (!IsSuccessStatusCode(owinResponse.StatusCode) && responseBuffer.Length > 0) {
//NOTE: perform your own content negotiation if desired but for this, using JSON
var body = await CreateCommonApiResponse(owinResponse, responseBuffer);
var content = JsonConvert.SerializeObject(body);
var mediaType = MediaTypeHeaderValue.Parse(owinResponse.ContentType);
using (var customResponseBody = new StringContent(content, Encoding.UTF8, mediaType.MediaType)) {
var customResponseStream = await customResponseBody.ReadAsStreamAsync();
await customResponseStream.CopyToAsync(owinResponseStream, (int)customResponseStream.Length, owinRequest.CallCancelled);
owinResponse.ContentLength = customResponseStream.Length;
}
} else {
//copy buffer to response stream this will push it down to client
await responseBuffer.CopyToAsync(owinResponseStream, (int)responseBuffer.Length, owinRequest.CallCancelled);
owinResponse.ContentLength = responseBuffer.Length;
}
}
}
async Task<object> CreateCommonApiResponse(IOwinResponse response, Stream stream) {
var json = await new StreamReader(stream).ReadToEndAsync();
var statusCode = ((HttpStatusCode)response.StatusCode).ToString();
var responseReason = response.ReasonPhrase ?? statusCode;
//Is this a HttpError
var httpError = JsonConvert.DeserializeObject<HttpError>(json);
if (httpError != null) {
return new {
error = httpError.Message ?? responseReason,
error_description = (object)httpError.MessageDetail
?? (object)httpError.ModelState
?? (object)httpError.ExceptionMessage
};
}
//Is this an OAuth Error
var oAuthError = Newtonsoft.Json.Linq.JObject.Parse(json);
if (oAuthError["error"] != null && oAuthError["error_description"] != null) {
dynamic obj = oAuthError;
return new {
error = (string)obj.error,
error_description = (object)obj.error_description
};
}
//Is this some other unknown error (Just wrap in common model)
var error = JsonConvert.DeserializeObject(json);
return new {
error = responseReason,
error_description = error
};
}
bool IsSuccessStatusCode(int statusCode) {
return statusCode >= 200 && statusCode <= 299;
}
}
}
...and registered early in the pipeline before the the authentication middlewares and web api handlers are added.
public class Startup {
public void Configuration(IAppBuilder app) {
app.UseResponseEncrypterMiddleware();
app.UseRequestLogger();
//...(after logging middle ware)
app.UseCommonErrorResponse();
//... (before auth middle ware)
//...code removed for brevity
}
}
This example is just a basic start. It should be simple enough able to extend this starting point.
Though in this example the common model looks like what is returned from OAuthProvider, any common object model can be used.
Tested it with a few In-memory Unit Tests and through TDD was able to get it working.
[TestClass]
public class UnifiedErrorMessageTests {
[TestMethod]
public async Task _OWIN_Response_Should_Pass_When_Ok() {
//Arrange
var message = "\"Hello World\"";
var expectedResponse = "\"I am working\"";
using (var server = TestServer.Create<WebApiTestStartup>()) {
var client = server.HttpClient;
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
var content = new StringContent(message, Encoding.UTF8, "application/json");
//Act
var response = await client.PostAsync("/api/Foo", content);
//Assert
Assert.IsTrue(response.IsSuccessStatusCode);
var result = await response.Content.ReadAsStringAsync();
Assert.AreEqual(expectedResponse, result);
}
}
[TestMethod]
public async Task _OWIN_Response_Should_Be_Unified_When_BadRequest() {
//Arrange
var expectedResponse = "invalid_grant";
using (var server = TestServer.Create<WebApiTestStartup>()) {
var client = server.HttpClient;
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
var content = new StringContent(expectedResponse, Encoding.UTF8, "application/json");
//Act
var response = await client.PostAsync("/api/Foo", content);
//Assert
Assert.IsFalse(response.IsSuccessStatusCode);
var result = await response.Content.ReadAsAsync<dynamic>();
Assert.AreEqual(expectedResponse, (string)result.error_description);
}
}
[TestMethod]
public async Task _OWIN_Response_Should_Be_Unified_When_MethodNotAllowed() {
//Arrange
var expectedResponse = "Method Not Allowed";
using (var server = TestServer.Create<WebApiTestStartup>()) {
var client = server.HttpClient;
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
//Act
var response = await client.GetAsync("/api/Foo");
//Assert
Assert.IsFalse(response.IsSuccessStatusCode);
var result = await response.Content.ReadAsAsync<dynamic>();
Assert.AreEqual(expectedResponse, (string)result.error);
}
}
[TestMethod]
public async Task _OWIN_Response_Should_Be_Unified_When_NotFound() {
//Arrange
var expectedResponse = "Not Found";
using (var server = TestServer.Create<WebApiTestStartup>()) {
var client = server.HttpClient;
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
//Act
var response = await client.GetAsync("/api/Bar");
//Assert
Assert.IsFalse(response.IsSuccessStatusCode);
var result = await response.Content.ReadAsAsync<dynamic>();
Assert.AreEqual(expectedResponse, (string)result.error);
}
}
public class WebApiTestStartup {
public void Configuration(IAppBuilder app) {
app.UseCommonErrorMessageMiddleware();
var config = new HttpConfiguration();
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);
app.UseWebApi(config);
}
}
public class FooController : ApiController {
public FooController() {
}
[HttpPost]
public IHttpActionResult Bar([FromBody]string input) {
if (input == "Hello World")
return Ok("I am working");
return BadRequest("invalid_grant");
}
}
}
ORIGINAL ANSWER (Use DelegatingHandler)
Consider using a DelegatingHandler
Quoting from an article found online.
Delegating handlers are extremely useful for cross cutting concerns.
They hook into the very early and very late stages of the
request-response pipeline making them ideal for manipulating the
response right before it is sent back to the client.
This example is a simplified attempt at the unified error message for HttpError responses
public class HttpErrorHandler : DelegatingHandler {
protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) {
var response = await base.SendAsync(request, cancellationToken);
return NormalizeResponse(request, response);
}
private HttpResponseMessage NormalizeResponse(HttpRequestMessage request, HttpResponseMessage response) {
object content;
if (!response.IsSuccessStatusCode && response.TryGetContentValue(out content)) {
var error = content as HttpError;
if (error != null) {
var unifiedModel = new {
error = error.Message,
error_description = (object)error.MessageDetail ?? error.ModelState
};
var newResponse = request.CreateResponse(response.StatusCode, unifiedModel);
foreach (var header in response.Headers) {
newResponse.Headers.Add(header.Key, header.Value);
}
return newResponse;
}
}
return response;
}
}
Though this example is very basic, it is trivial to extend it to suit your custom needs.
Now it is just a matter of adding the handler to the pipeline
public static class WebApiConfig {
public static void Register(HttpConfiguration config) {
config.MessageHandlers.Add(new HttpErrorHandler());
// Other code not shown...
}
}
Message handlers are called in the same order that they appear in
MessageHandlers collection. Because they are nested, the response message travels in the other direction. That is, the last handler is
the first to get the response message.
Source: HTTP Message Handlers in ASP.NET Web API

is it possible to replace message with error in response that is
returned by ModelValidatorProviders
We may use overloaded SetError to do it otherwise, replace error with message.
BaseValidatingContext<TOptions>.SetError Method (String)
Marks this context as not validated by the application and assigns various error information properties. HasError becomes true and IsValidated becomes false as a result of calling.
string msg = "{\"message\": \"Account locked.\"}";
context.SetError(msg);
Response.StatusCode = 400;
context.Response.Write(msg);

Calling remote web api from mvc controller

What is the preferred way for handling web api endpoints for each controller?
For example, my MVC controller will be calling different endpoints.
These are the only ones for now, but it could change.
Also, I will be developing this locally and and deploying to development server.
http://localhost:42769/api/categories/1/products
http://localhost:42769/api/products/
public class ProductsController : Controller
{
HttpClient client;
string url = "http://localhost:42769/api/categories/1/products"; //api/categories/{categoryId}/products
public ProductsController()
{
client = new HttpClient();
client.BaseAddress = new Uri(url);
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
}
// GET: Products
public async Task<ActionResult> ProductsByCategory()
{
HttpResponseMessage responseMessage = await client.GetAsync(url);
if (responseMessage.IsSuccessStatusCode)
{
var responseData = responseMessage.Content.ReadAsStringAsync().Result;
var products = JsonConvert.DeserializeObject<List<GetProductsByCategoryID>>(responseData);
return PartialView(products);
}
return View("Error");
}
}

Not sure I understand you question or problem, but I would create a wrapper class for the service and then have different methods for each resource that you need to call. Always think SOLID.
Example (written by hand)
public class Client
{
private Uri baseAddress;
public Client(Uri baseAddress)
{
this.baseAddress = baseAddress;
}
public IEnumerable<Products> GetProductsFromCategory(int categoryId)
{
return Get<IEnumerable<Product>>($"api/categories/{categoryId}/products");
}
public IEnumerable<Products> GetAllProducts()
{
return Get<IEnumerable<Product>>($"api/products");
}
private T Get<T>(string query)
{
using(var httpClient = new HttpClient())
{
httpClient.BaseAddress = baseAddress;
var response= httpClient.Get(query).Result;
return response.Content.ReadAsAsync<T>().Result;
}
}
}

httpclient call to webapi to post data not working

I need to make a simple webapi call to post method with string argument.
Below is the code I'm trying, but when the breakpoint is hit on the webapi method, the received value is null.
StringContent stringContent = new System.Net.Http.StringContent("{ \"firstName\": \"John\" }", System.Text.Encoding.UTF8, "application/json");
HttpClient client = new HttpClient();
HttpResponseMessage response = await client.PostAsync(url.ToString(), stringContent);
and server side code:
// POST api/values
[HttpPost]
public void Post([FromBody]string value)
{
}
please help...

If you want to send a json to your Web API, the best option is to use a model binding feature, and use a Class, instead a string.
Create a model
public class MyModel
{
[JsonProperty("firstName")]
public string FirstName { get; set; }
}
If you wont use the JsonProperty attribute, you can write property in lower case camel, like this
public class MyModel
{
public string firstName { get; set; }
}
Then change you action, change de parameter type to MyModel
[HttpPost]
public void Post([FromBody]MyModel value)
{
//value.FirstName
}
You can create C# classes automatically using Visual Studio, look this answer here Deserialize JSON into Object C#
I made this following test code
Web API Controller and View Model
using System.Web.Http;
using Newtonsoft.Json;
namespace WebApplication3.Controllers
{
public class ValuesController : ApiController
{
[HttpPost]
public string Post([FromBody]MyModel value)
{
return value.FirstName.ToUpper();
}
}
public class MyModel
{
[JsonProperty("firstName")]
public string FirstName { get; set; }
}
}
Console client application
using System;
using System.Net.Http;
namespace Temp
{
public class Program
{
public static void Main(string[] args)
{
Console.WriteLine("Enter to continue");
Console.ReadLine();
DoIt();
Console.ReadLine();
}
private static async void DoIt()
{
using (var stringContent = new StringContent("{ \"firstName\": \"John\" }", System.Text.Encoding.UTF8, "application/json"))
using (var client = new HttpClient())
{
try
{
var response = await client.PostAsync("http://localhost:52042/api/values", stringContent);
var result = await response.Content.ReadAsStringAsync();
Console.WriteLine(result);
}
catch (Exception ex)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine(ex.Message);
Console.ResetColor();
}
}
}
}
}
Output
Enter to continue
"JOHN"

Alternative answer: You can leave your input parameter as string
[HttpPost]
public void Post([FromBody]string value)
{
}
, and call it with the C# httpClient as follows:
var kvpList = new List<KeyValuePair<string, string>>
{
new KeyValuePair<string, string>("", "yo! r u dtf?")
};
FormUrlEncodedContent rqstBody = new FormUrlEncodedContent(kvpList);
string baseUrl = "http://localhost:60123"; //or "http://SERVERNAME/AppName"
string C_URL_API = baseUrl + "/api/values";
using (var httpClient = new HttpClient())
{
try
{
HttpResponseMessage resp = await httpClient.PostAsync(C_URL_API, rqstBody); //rqstBody is HttpContent
if (resp != null && resp.Content != null) {
var result = await resp.Content.ReadAsStringAsync();
//do whatevs with result
} else
//nothing returned.
}
catch (Exception ex)
{
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine(ex.Message);
Console.ResetColor();
}
}

For the record I tried the above and could not get it working!
I couldn't get it working because my API was in a separate project. Which is fine right? no, I was doing Dependency Injection into the controller while using the Startup class against the Base project.
You can resolve this by using the WebAPI's config and configuring Dependency Injection there with Unity. The below code works for me:
WebApiConfig.cs:
public static void Register(HttpConfiguration config)
{
config.MapHttpAttributeRoutes();
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);
RegisterUnity();
}
private static void RegisterUnity()
{
var container = new UnityContainer();
container.RegisterType<IIdentityRespository, IdentityRespository>();
GlobalConfiguration.Configuration.DependencyResolver = new UnityDependencyResolver(container);
}
}
I hope it helps others :-)