I need to send async request to the server and get the information from the response stream.
I'm using HttpClient.GetStreamAsync(), but the server response that POST should be used. Is there a similar method like PostStreamAsync()? Thank you.
If you want to use HttpClient for streaming large data then you should not use PostAsync cause message.Content.ReadAsStreamAsync would read the entire stream into memory. Instead you can use the following code block.
var message = new HttpRequestMessage(HttpMethod.Post, "http://localhost:3100/api/test");
var response = await client.SendAsync(message, HttpCompletionOption.ResponseHeadersRead);
var stream = await response.Content.ReadAsStreamAsync();
The key thing here is the HttpCompletionOption.ResponseHeadersRead option which tells the client not to read the entire content into memory.
Use HttpClient.PostAsync and you can get the response stream via HttpResponseMessage.Content.ReadAsStreamAsync() method.
var message = await client.PostAsync(url, content);
var stream = await message.Content.ReadAsStreamAsync();
Instead of HttpClient, maybe you should use HttpWebRequest ?
They offer both async method and the possibility to switch between post and get by setting their method property.
e.g:
var request = (HttpWebRequest) WebRequest.Create(uri);
request.Method = "POST";
var postStream = await request.GetRequestStreamAsync()
Related
I'm sending a request with HttpClient to a remote endpoint. I want to download the content and save it to a file as an UTF-8 string.
If the server would respond with the proper Content-Type text/plain; charset=utf-8, then the following code processes it just fine:
HttpClient client = new();
HttpResponseMessage res = await client.GetAsync(url);
string text = await res.Content.ReadAsStringAsync();
File.WriteAllText("file.txt", text);
However, the server always returns the basic Content-Type text/plain and I'm unable to get that as an UTF-8 string.
HttpClient cl = new();
HttpResponseMessage res = await cl.GetAsync(url);
string attempt1 = await res.Content.ReadAsStringAsync();
string attempt2 = Encoding.UTF8.GetString(await res.Content.ReadAsByteArrayAsync());
Stream stream = await res.Content.ReadAsStreamAsync();
byte[] bytes = ((MemoryStream)stream).ToArray();
string attempt3 = Encoding.UTF8.GetString(bytes);
I tried all three of these approaches, all resulted in scrambled characters due to the encoding mismatch. I don't have control over the server, so I can't change the headers.
Is there any way to force HttpClient to parse it as UTF-8? Why are the manual approaches not working?
I've built a Cloudflare worker to demonstrate this behavior and allow you to easily debug:
https://headers.briganreiz.workers.dev/charset-in-header
https://headers.briganreiz.workers.dev/no-charset
Edit: Turns out it was the GZip compression on the main server which I didn't notice. This question solved it for me: Decompressing GZip Stream from HTTPClient Response
I find it works well with these different classes WebRequest and HttpWebResponse. I have not added plumbing for resp.StatusCode etc but obviously presuming all went well is a tad naive.
Give it a go i am sure You'll find the WebRequest and HttpWebResponse more capable for dynamic requests (?)
var req = WebRequest.CreateHttp(url)
var getResponse = req.GetResponseAsync();
getResponse.Wait(ResponseTimeoutMilliseconds);
var resp = (HttpWebResponse)getResponse.Result;
using (Stream responseStream = resp.GetResponseStream())
{
var reader = new StreamReader(responseStream, Encoding.UTF8);
string content = reader.ReadToEnd();
}
Obviously once you have things working, you should absolutely use the ..Async versions but for debugging, since we already waited for response it is more convenient to simply step through i find, feel free to not take that middle step :)
Im making some automatic surveillance for an Rest API im running and i need to retrieve the response body from the HttpResponseMessage object.
Im using Flurl Http: https://flurl.dev/docs/fluent-http/
I know how to retrieve the responsebody by adding ".RecieveSomeForm()" at the end of the http request, but i also need to get the response headers, as the error code from the Rest API is sent back as a header. My problem is that - to my knowledge and what i tried - its only the HttpResponseMessage object that i can retrieve the headers from. So the question is:
How do i get the responsebody out of the HttpResponseMessage while still being able to retrieve the headers for error logging?
using (var cli = new FlurlClient(URL).EnableCookies())
{
//get response body - var is set to string and has only response body
var AsyncResponse = await cli.WithHeader("some header").Request("some end point").AllowAnyHttpStatus().PostJsonAsync(some body).ReceiveString();
Console.WriteLine(AsyncResponse);
//get headers - var is set to HttpResponseMessage
var AsyncResponse = await cli.WithHeader("some header").Request("some end point").AllowAnyHttpStatus().PostJsonAsync(some body);
Console.WriteLine(AsyncResponse.Headers);
}
If I've understood correctly, you want Headers + Response body from a HTTP response.
var response = await cli.WithHeader("some header").Request("some end point").AllowAnyHttpStatus().PostJsonAsync("some body");
var headers = response.Headers; //do your stuff
var responseBody = response.Content != null ? await response.Content.ReadAsStringAsync() : null;
Another option which I personally don't like:
var responseTask = cli.WithHeader("some header", "haha").Request("some end point").AllowAnyHttpStatus().PostJsonAsync("some body");
var headers = (await responseTask).Headers; //do your stuff
var responseBody = await responseTask.ReceiveString();
Unfortunately, Flurl's extension methods can be used on Task, not on HttpResponseMessage. (that's why you have to avoid awaiting in the first line of code)
I have an api
http://cbastest.cadvilpos.com/module/posmodule/customapi
with parameters
{
"action":4,
"device_token": "3e8ea119a90ee6d2",
"key":"9475962085b3a1b8c475d52.95782804",
"shop":1,
"language":1
}
This is working fine in postman. But when I try to connect from c# project its showing an error {"success":0,"error":"Missing the action parameter."}. Please give a working C# code to get the json result.
The code I tried:
var request = (HttpWebRequest)WebRequest.Create("http://cbastest.cadvilpos.com/module/posmodule/customapi");
var postData = "{ 'action':'4', 'device_token':'3e8ea119a90ee6d2','key':'9475962085b3a1b8c475d52.95782804','shop':'1','language':'1'}";
var data = Encoding.ASCII.GetBytes(postData);
request.Method = "POST";
request.ContentType = "application/json";
request.ContentLength = data.Length;
using (var stream = request.GetRequestStream())
{
stream.Write(data, 0, data.Length);
}
var response2 = (HttpWebResponse)request.GetResponse();
var responseString = new StreamReader(response2.GetResponseStream()).ReadToEnd();
You don't need to use a raw HttpWebRequest object to make an HTTP call. HttpClient was introduced in 2012 to allow easy asynchronous HTTP calls.
You could do something as simple as :
var content=new StringContent(postData,Encoding.UTF8, "application/json");
HttpResponseMessage response=await httpClient.PostAsync(url,content);
//Now process the response
if (response.IsSuccessCode)
{
var body=await response.Content.ReadAsStringAsync();
var responseDTO=JsonConvert.DeserializeObject<MyDTO>(body);
}
Instead of building a JSON string by hand you could use a strongly typed class or an anonymous object and serialize it to JSON with JSON.NET :
var data=new {
action=4,
device_token="3e8ea119a90ee6d2",
key = "9475962085b3a1b8c475d52.95782804",
shop=1,
language=1
};
var postData=JsonConvert.SerializeObject(data);
var content=new StringContent(postData,Encoding.UTF8, "application/json");
var response=await httpClient.PostAsync(url,content);
...
You can read a response body in one go as a string, using ReadAsStringAsync or you can get the response stream with ReadAsStreamAsync. You could copy the response data directly to another stream, eg a file or memory stream with HttpContent.CopyToAsync
Check Call a Web API from a .NET Client for more examples. Despite the title, the examples work to call any HTTP/REST API.
The Microsoft.AspNet.WebApi.Client package mentioned in that article is another thing that applies to any call, not just calls to ASP.NET Web API. The extension method PostAsJsonAsync for example, combines serializing and posting a request to a url. Using it, posting the action DTO could be reduced to a single line:
var data=new {
action=4,
device_token="3e8ea119a90ee6d2",
key = "9475962085b3a1b8c475d52.95782804",
shop=1,
language=1
};
var response=await httpClient.PostAsJsonAsync(url,data);
There is a button in Postman that will generate code for the currently defined request. The link is here:
And this is what the code looks like. You'll need to pull in RestSharp from Nuget
Used the Flurl to Get response from API.
var response = await url.WithClient(fc)
.WithHeader("Authorization", requestDto.ApiKey)
.GetJsonAsync<T>();
dynamic httpResponse = response.Result;
But I cant able to access httpResponse.Headers
How to access response headers while using GetJsonAsync .
You can't get a header from GetJsonAsync<T> because it returns Task<T> instead of raw response. You can call GetAsync and deserialize your payload at next step:
HttpResponseMessage response = await url.GetAsync();
HttpResponseHeaders headers = response.Headers;
FooPayload payload = await response.ReadFromJsonAsync<FooPayload>();
ReadFromJsonAsync is an extention method:
public static async Task<TBody> ReadFromJsonAsync<TBody>(this HttpResponseMessage response)
{
if (response.Content == null) return default(TBody);
string content = await response.Content.ReadAsStringAsync();
return JsonConvert.DeserializeObject<TBody>(content);
}
P.S. This is why I prefer and recommend to use raw HttpClient instead of any third-party high-level client like RestSharp or Flurl.
You could also await for the HttpResponseMessage, pick off the .Headers object, then send the completed task to ReceiveJson<T> for deserialization. Here's how to do it without an extension method:
var task = url.GetAsync();
HttpResponseMessage response = await task;
HttpResponseHeaders headers = response.Headers;
//Get what I need now from headers, .ReceiveJson<T>() will dispose
//response object above.
T obj = await task.ReceiveJson<T>();
I've just noticed some behavior in C# that's thrown me off a little. I'm using C# 5 and .NET 4.5. When I call GetResponseStream() on a HTTPResponse object I am able to get the response stream, but if I call it again on the same object the response is blank.
// Works! Body of the response is in the source variable.
HttpResponse response = (HttpWebResponse)request.GetResponse();
String source = new StreamReader(response.GetResponseStream()).ReadToEnd();
// Does Not Work. Source is empty;
String source2 = new StreamReader(response.GetResponseStream()).ReadToEnd();
The above is just an example to demonstrate the problem.
Edit
This is what I'm trying to do. Basically if an event is attached to the HTTP object it will pass a response back to the callback method.
HttpWebResponse public Get(String url)
{
// HttpWebRequest ...
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
// postRequest is an event handler. The response is passed to the
// callback to do whatever it needs to do.
if (this.postRequest != null)
{
RequestEventArgs requestArgs = new RequestEventArgs();
requestArgs.source = response;
postRequest.Invoke(this, requestArgs);
}
return response;
}
In the callback method I may want to check the body of the response. If I do, I lose the the data from the response when Get() returns the response.
The response stream reads directly from the network connection.
Once you read it to the end (in the 2nd line), there is no more data to read.