Develop Reference

HttpClient send null POST data

Well... I read A LOT of questions here in StackOverflow, but still didn't get answer for it, I have this Web API controller:
public class ERSController : ApiController
{
[HttpGet]
public HttpResponseMessage Get()
{
var resposne = new HttpResponseMessage(HttpStatusCode.OK);
resposne.Content = new StringContent("test OK");
return resposne;
}
[HttpPost]
public HttpResponseMessage Post([FromUri]string ID,[FromBody] string Data)
{
var resposne = new HttpResponseMessage(HttpStatusCode.OK);
//Some actions with database
resposne.Content = new StringContent("Added");
return resposne;
}
}
and I wrote a small tester to it:
static void Main(string[] args)
{
HttpClient client = new HttpClient();
client.BaseAddress = new Uri("http://localhost:54916/");
client.DefaultRequestHeaders.Accept.Clear();
var content = new StringContent("<data>Hello</data>", Encoding.UTF8, "application/json");
var response = client.PostAsync("api/ERS?ID=123", content);
response.ContinueWith(p =>
{
string result = p.Result.Content.ReadAsStringAsync().Result;
Console.WriteLine(result);
});
Console.ReadKey();
}
I always get NULL on the parameter Data in the API.
I tried adding those lines to the tester:
client.DefaultRequestHeaders
.Accept
.Add(new MediaTypeWithQualityHeaderValue("application/json"));
still NULL, I also replace the content with:
var values = new Dictionary<string, string>();
values.Add("Data", "Data");
var content = new FormUrlEncodedContent(values);
still NULL.
I tried switching the request to:
WebClient client = new WebClient();
client.Headers[HttpRequestHeader.ContentType] = "application/x-www-form-urlencoded";
var values = new NameValueCollection();
values["Data"] = "hello";
var task = client.UploadValuesTaskAsync("http://localhost:54916/api/ERS?ID=123", values);
task.ContinueWith((p) =>
{
string response = Encoding.UTF8.GetString(p.Result);
Console.WriteLine(response);
});
but debugger still saying 'NO!' the Data is still NULL.
I do get the ID with no problem.

If you want to send it as a JSON string, you should do this (using Newtonsoft.Json):
var serialized = JsonConvert.SerializeObject("Hello");
var content = new StringContent(serialized, Encoding.UTF8, "application/json");
You almost got it right with FormUrlEncodedContent, what you had to do was send it with an empty name, like in this example:
var content = new FormUrlEncodedContent(new[]
{
new KeyValuePair<string, string>("", "Hello")
});
var response = client.PostAsync("api/ERS?ID=123", content);

C# - Body content in POST request

I need to make some api calls in C#. I'm using Web API Client from Microsoft to do that. I success to make some POST requests, but I don't know how to add the field "Body" into my requests. Any idea ?
Here's my code:
static HttpClient client = new HttpClient();
public override void AwakeFromNib()
{
base.AwakeFromNib();
notif_button.Activated += (sender, e) => {
};
tips_button.Activated += (sender, e) =>
{
Tip t1 = new Tip(title_tips.StringValue, pic_tips.StringValue, content_tips.StringValue, "TEST");
client.BaseAddress = new Uri("my_url");
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
CreateProductAsync(t1).Wait();
};
}
static async Task<Uri> CreateProductAsync(Tip tips)
{
HttpResponseMessage response = await client.PostAsJsonAsync("api/add_tips", tips);
response.EnsureSuccessStatusCode();
return response.Headers.Location;
}

Step 1. Choose a type that derives from HttpContent. If you want to write a lot of content with runtime code, you could use a StreamContent and open some sort of StreamWriter on it. For something short, use StringContent. You can also derive your own class for custom content.
Step 2. Pass the content in a call to HttpClient.PostAsync.
Here's an example that uses StringContent to pass some JSON:
string json = JsonConvert.SerializeObject(someObject);
var httpContent = new StringContent(json, Encoding.UTF8, "application/json");
var httpResponse = await httpClient.PostAsync("http://www.foo.bar", httpContent);
See also How do I set up HttpContent?.

Thanks to this and this, I finally found the solution to send post requests with headers AND body content. Here's the code:
var cl = new HttpClient();
cl.BaseAddress = new Uri("< YOUR URL >");
int _TimeoutSec = 90;
cl.Timeout = new TimeSpan(0, 0, _TimeoutSec);
string _ContentType = "application/x-www-form-urlencoded";
cl.DefaultRequestHeaders.Add(key, value);
cl.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue(_ContentType));
cl.DefaultRequestHeaders.Add("key", "value");
cl.DefaultRequestHeaders.Add("key", "value");
var _UserAgent = "d-fens HttpClient";
cl.DefaultRequestHeaders.Add("User-Agent", _UserAgent);
var nvc = new List<KeyValuePair<string, string>>();
nvc.Add(new KeyValuePair<string, string>("key of content", "value"));
var req = new HttpRequestMessage(HttpMethod.Post, "http://www.t-lab.fr:3000/add_tips") { Content = new FormUrlEncodedContent(nvc) };
var res = cl.SendAsync(req);

a little more understandable
using (var client = new HttpClient())
{
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/x-www-form-urlencoded"));
client.DefaultRequestHeaders.Add("Accept", "*/*");
var Parameters = new List<KeyValuePair<string, string>>
{
new KeyValuePair<string, string>("Id", "1"),
};
var Request = new HttpRequestMessage(HttpMethod.Post, "Post_Url")
{
Content = new FormUrlEncodedContent(Parameters)
};
var Result = client.SendAsync(Request).Result.Content.ReadAsStringAsync();
}

httpclient header + content joined PostAsyn

I am trying to make a PostAsync request with c#. The following is my code.
static void Main(string[] args)
{
CookieContainer cookies = new CookieContainer();
HttpClientHandler handler = new HttpClientHandler();
handler.CookieContainer = cookies;
using (var client = new HttpClient(handler))
{
using (HttpResponseMessage getResponse = client.GetAsync("http://google.com").Result)
{
CheckStatusCode(getResponse);
String header = getResponse.Headers.ToString();
var content = CreateCollection(getResponse.Content);
var _stringHeaderContent = header + "\r" + content;
HttpContent _content = new StringContent(_stringHeaderContent, Encoding.UTF8);
Console.WriteLine(_content);
using (HttpResponseMessage postResponse = client.PostAsync("http://google.com",_content).Result)
{
Console.WriteLine(postResponse.Headers);
CheckStatusCode(postResponse);
Console.WriteLine(postResponse.Headers);
}
}
}
}
methods:
public static void CheckStatusCode(HttpResponseMessage response)
{
if (response.StatusCode != HttpStatusCode.OK)
throw new Exception(String.Format(
"Server error (HTTP {0}: {1}).",
response.StatusCode,
response.ReasonPhrase));
else
Console.WriteLine("200");
}
public static String CreateCollection(HttpContent content)
{
var myContent = content.ReadAsStringAsync().Result;
HtmlNode.ElementsFlags.Remove("form");
string html = myContent;
var doc = new HtmlAgilityPack.HtmlDocument();
doc.LoadHtml(html);
var input = doc.DocumentNode.SelectSingleNode("//*[#name='__Token']");
var token = input.Attributes["value"].Value;
//add all necessary component to collection
NameValueCollection collection = new NameValueCollection();
collection.Add("__Token", token);
collection.Add("returnURL", "");
collection.Add("Email", "11111111#hotmail.com");
collection.Add("Password", "1234");
String queryString = GenerateQueryString(collection);
return queryString;
}
public static string GenerateQueryString(NameValueCollection collection)
{
var array = (from key in collection.AllKeys
from value in collection.GetValues(key)
select string.Format("{0}={1}", WebUtility.UrlEncode(key), WebUtility.UrlEncode(value))).ToArray();
return string.Join("&", array);
}
The problem I am having with this code is nothing gets stored in _content. I am trying to make a postAsync request with the header and a part of the content joined. however when I make the postAsync request nothing is stored in _content. Therefore the request fails.
Can anyone explain to me how I can make a postAsync request with _stringHeaderContent?
Regards

This is the way how to use PostAsync:
...
var httpClient = new HttpClient();
var postData = new List<KeyValuePair<string, string>>();
postData.Add(new KeyValuePair<string, string>("a", "1"));
postData.Add(new KeyValuePair<string, string>("b", "2"));
var content = new FormUrlEncodedContent(postData);
var result = httpClient.PostAsync("http://127.0.0.1/a.php", content).Result;
...

HttpClient: The uri string is too long

Given the following attempt to post data to a web service that generates PDF files, PDF rocket (which is awesome by the way).
I get the error Invalid URI: The uri string is too long
Why would anyone impose an arbitrary limit on POSTed data?
using (var client = new HttpClient())
{
// Build the conversion options
var options = new Dictionary<string, string>
{
{ "value", html },
{ "apikey", ConfigurationManager.AppSettings["pdf:key"] },
{ "MarginLeft", "10" },
{ "MarginRight", "10" }
};
// THIS LINE RAISES THE EXCEPTION
var content = new FormUrlEncodedContent(options);
var response = await client.PostAsync("https://api.html2pdfrocket.com/pdf", content);
var result = await response.Content.ReadAsByteArrayAsync();
return result;
}
I receive this rediculous error.
{System.UriFormatException: Invalid URI: The Uri string is too long.
at System.UriHelper.EscapeString
at System.Uri.EscapeDataString
at System.Net.Http.FormUrlEncodedContent.Encode
at System.Net.Http.FormUrlEncodedContent.GetContentByteArray
This reminds me of 640k ought to be enough... I mean really?

If, like me, you're faced with some wonky 3rd party web service that will only accept form content, you can work around the problem like this:
// Let's assume you've got your key-value pairs organised into a nice Dictionary<string, string> called formData
var encodedItems = formData.Select(i => WebUtility.UrlEncode(i.Key) + "=" + WebUtility.UrlEncode(i.Value));
var encodedContent = new StringContent(String.Join("&", encodedItems), null, "application/x-www-form-urlencoded");
// Post away!
var response = await client.PostAsync(url, encodedContent);

With a post can include the content in the http message instead of the URI. A uri has a max length of 2083 characters. You could send it as JSON in the http message instead of the URI which is the recommended way to send larger chunks of data in an HttpPost/HttpPut. I altered your code to make use of it. This assumes that your service you are contacting can work with JSON (.net Web Api out of the box should have no problem with this).
using (var client = new HttpClient())
{
// Build the conversion options
var options = new
{
value = html,
apikey = ConfigurationManager.AppSettings["pdf:key"],
MarginLeft = "10",
MarginRight = "10"
};
// Serialize our concrete class into a JSON String
var stringPayload = JsonConvert.SerializeObject(options);
var content = new StringContent(stringPayload, Encoding.UTF8, "application/json");
var response = await client.PostAsync("https://api.html2pdfrocket.com/pdf", content);
var result = await response.Content.ReadAsByteArrayAsync();
return result;
}
Make sure to install newtonsoft json.

I just solved a similar problem. For me I was integrating with a backend I didn't control and had to POST file along with form data (eg customerID) as form variables. So switching to JSON or Multipart would break the backend I didn't control. The problem was that large files would cause the FormUrlEncodedContent to throw an error saying "The uri string is too long".
This is the code that solved it for me after two days of effort (note still needs to be tweaked to be ASYNC).
private string UploadFile(string filename, int CustomerID, byte[] ImageData) {
string Base64String = "data:image/jpeg;base64," + Convert.ToBase64String(ImageData, 0, ImageData.Length);
var baseAddress = new Uri("[PUT URL HERE]");
var cookieContainer = new CookieContainer();
using (var handler = new HttpClientHandler() { AllowAutoRedirect = true, UseCookies = true, CookieContainer = cookieContainer })
using (var client = new HttpClient(handler) { BaseAddress = baseAddress })
{
try {
//ENCODE THE FORM VARIABLES DIRECTLY INTO A STRING rather than using a FormUrlEncodedContent type which has a limit on its size.
string FormStuff = string.Format("name={0}&file={1}&id={2}", filename, HttpUtility.UrlEncode(Base64String), CustomerID.ToString());
//THEN USE THIS STRING TO CREATE A NEW STRINGCONTENT WHICH TAKES A PARAMETER WHICH WILL FormURLEncode IT AND DOES NOT SEEM TO THROW THE SIZE ERROR
StringContent content = new StringContent(FormStuff, Encoding.UTF8, "application/x-www-form-urlencoded");
//UPLOAD
string url = string.Format("/ajax/customer_image_upload.php");
response = client.PostAsync(url, content).Result;
return response.Content.ToString();
}
catch (Exception ex) {
return ex.ToString();
}
}
}

#Mick Byrne :
Thanks - your solution worked like a charme!
Here is my complete code:
public async Task DateienSendenAsync (string PfadUndDatei, string Dateiname, String VRPinGUID, String ProjektGUID, String VRPinX, String VRPinY, String VRPinZ)
{
var client = new HttpClient();
// Create the HttpContent for the form to be posted.
var requestContent = new[] {
new KeyValuePair<string, string>("dateiname", Dateiname),
new KeyValuePair<string, string>("bild", Convert.ToBase64String(File.ReadAllBytes(PfadUndDatei))),
new KeyValuePair<string, string>("VRPinGUID", VRPinGUID),
new KeyValuePair<string, string>("ProjektGUID", ProjektGUID),
new KeyValuePair<string, string>("ebene", "ebene"),
new KeyValuePair<string, string>("raumnummer", "raumnummer"),
new KeyValuePair<string, string>("ansichtsname", "ansichtsname"),
new KeyValuePair<string, string>("VRPinX", VRPinX),
new KeyValuePair<string, string>("VRPinY", VRPinY),
new KeyValuePair<string, string>("VRPinZ", VRPinZ),
};
String url = "http://yourhomepage/path/upload.php";
var encodedItems = requestContent.Select(i => WebUtility.UrlEncode(i.Key) + "=" + WebUtility.UrlEncode(i.Value));
var encodedContent = new StringContent(String.Join("&", encodedItems), null, "application/x-www-form-urlencoded");
// Post away!
var response = await client.PostAsync(url, encodedContent);
}

How to call [HttpPost] method of web api in c#

I have one method and i need to call it.
[HttpPost]
public List<MyClass> GetPanels(SomeModel filter)
{
...
//doing something with filter...
...
return new List<MyClass>();
}
I need to call this method by httpclient or HttpWebRequest , i mean any way.

Using the HttpClient you can do like this:
var client = new HttpClient();
var content = new StringContent(JsonConvert.SerializeObject(new SomeModel {Message = "Ping"}));
content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
var response = await client.PostAsync("http://localhost/yourhost/api/yourcontroller", content);
var value = await response.Content.ReadAsStringAsync();
var data = JsonConvert.DeserializeObject<MyClass[]>(value);
// do stuff

I would recommend you to use WebClient. Here is the example:
using (var wb = new WebClient())
{
var uri = new Uri("http://yourhost/api/GetPanels");
// Your headers, off course if you need it
wb.Headers.Add(HttpRequestHeader.Cookie, "whatEver=5");
// data - data you need to pass in POST request
var response = wb.UploadValues(uri, "POST", data);
}
ADDED
To convert your data to nameValue collection you can use next:
NameValueCollection formFields = new NameValueCollection();
data.GetType().GetProperties()
.ToList()
.ForEach(pi => formFields.Add(pi.Name, pi.GetValue(data, null).ToString()));
Then just use the formFields in POST request.