I'm trying to download a string from ANY webpage within my portable class library. I've created the most basic setup:
created a new PCL project
compatible with WP8 and WinRT as well as the compulsory components such as Silverlight
As WebClient is not compatible across these systems, it is not possible to use:
string data = new WebClient().DownloadString();
I've tried using this as well (uses this):
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.Method = HttpMethod.Get;
HttpWebResponse response = (HttpWebResponse)await request.GetResponseAsync();
string data = ""
using (var sr = new StreamReader(response.GetResponseStream()))
{
data = sr.ReadToEnd();
}
However, when I call the second set of code from an external C# application referencing the PCL, the debugger simply fails with NO warning or error message on:
request.GetResponseAsync();
Is there an easy way to download a string that I'm missing?
*also, why would the debugger simply exit with no explanation?
Edit:
Here is another method I have attempted - based on an answer already provided. Again, this method simply exits and force closes the debugger.
PCL Method:
public static async Task<string> DownloadString()
{
var url = "http://google.com";
var client = new HttpClient();
var data = await client.GetStringAsync(url);
return data;
}
Calling method:
private static async void Method()
{
string data = await PCLProject.Class1.DownloadString();
return data;
}
Install the NuGet packages:
Microsoft.Bcl.Async, which adds async/await support to PCLs.
Microsoft.Net.Http, which adds HttpClient support to PCLs.
Then you can do it the easy way:
var client = new HttpClient();
var data = await client.GetStringAsync(url);
This method worked for me, it returned the HTML source code from google.com:
public async void GetStringFromWebpage()
{
using (HttpClient wc = new HttpClient())
{
var data = await wc.GetStringAsync("http://google.com/");
Debug.WriteLine("string:" + data);
}
}
Related
I want to download data of this website into a json file but as I am quite new to coding with C# I cant manage to get the data. I want to get Data of https://discosweb.esoc.esa.int/api/objects the authorization via token works but I dont know how I can send a request so the server gives me a json back and I cant find a solution online. I cant give you a screenshot of the API because you have to be logged in to see it. Plz ask me for detailed information if you can help me. Thank you realy for trying.
The code I want to run is here.
class Program
{
static HttpClient client = new HttpClient();
static void Main(string[] args)
{
client.BaseAddress = new Uri("https://discosweb.esoc.esa.int");
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/vnd.api+json"));
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("my_token");
var httpRequest = (HttpWebRequest)WebRequest.Create(client.BaseAddress);
var httpResponse = (HttpWebResponse)httpRequest.GetResponse();
using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
{
var streamReaderResult = streamReader.ReadToEnd();
}
Console.WriteLine("Status https://discosweb.esoc.esa.int : " + httpResponse.StatusCode);
}
}
Try this
var url = "https://discosweb.esoc.esa.int/api/objects";
var httpRequest = (HttpWebRequest)WebRequest.Create(url);
httpRequest.Method = "POST";
httpRequest.Headers["Authorization"] = "Basic XXXx";
httpRequest.ContentType = "";
httpRequest.Headers["Content-Length"] = "0";
var httpResponse = (HttpWebResponse)httpRequest.GetResponse();
using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
{
var result = streamReader.ReadToEnd();
}
Console.WriteLine(httpResponse.StatusCode);
Where XXXx is user:password in base64.
Here is a basic implementation for making that API call to get the JSON result. You will need to parse that JSON into something other than a string but I'll assume you can handle that part.
This uses System.Net.HttpClient which is the modern HTTP api provided by .NET. Its operations are async so hopefully your code is or can be written to properly await async operations.
//Someplace convenient, create a shared HttpClient to avoid
//creating and disposing for each request.
HttpClient client = new HttpClient();
string data = await GetObjects(client);
//Example implementation
public async Task<string> GetObjects(HttpClient client)
{
string url = "https://discosweb.esoc.esa.int/api/objects";
using (HttpRequestMessage msg = new HttpRequestMessage(HttpMethod.Get, url))
{
msg.Headers.Authorization =
new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", "your personal access token here");
using (var result = await client.SendAsync(msg))
{
string content = await result.Content.ReadAsStringAsync();
return content;
}
}
}
While I may be a month late, I've actually developed an SDK for this particular API.
So, if you use this SDK it's pretty simple to do what you want. You can essentially forget about handling anything HTTP related, my SDK abstracts all of that away.
For example, to fetch Sputnik's data (which has an ID of 1) you'd run.
HttpClient innerClient = new();
innerClient.BaseAddress = "https://discosweb.esoc.esa.int/api/"
innerClient.DefaultRequestHeaders.Authorization = new("bearer", yourApiKey);
DiscosClient client = new();
DiscosObject sputnik = await client.GetSingle<DiscosObject>("1");
If you're using ASP.NET, there's a set of DI extensions that can actually set it all up for you, so you can skip the first three lines.
If you do choose to use it, please let me know, as it would be nice knowing my SDK is getting some use. If you have any issues, please just reach out through the GitHub issues page and I'll try to help!
I am trying to use Microsoft Project OData by querying data in C#. I am having performances issues with delays around 1s for each query. I am trying to query 2 information at once using that method :
public static async Task<string> ReadXml(string url)
{
var request = (HttpWebRequest)WebRequest.Create(url);
request.Credentials = Credentials; // SharePointOnlineCredentials
request.Headers.Add("X-FORMS_BASED_AUTH_ACCEPTED", "f");
using (var response = (HttpWebResponse)await request.GetResponseAsync())
using (var stream = response.GetResponseStream())
using (var reader = new System.IO.StreamReader(stream))
{
var xml = await reader.ReadToEndAsync();
return xml;
}
}
It works fine if I call it and always wait for it to end before calling it again, but I never receive any response from the WebRequest if I call it multiple times at once :
// just an example. I usually put a condition to filter for the tasks of a single project
var query1 = ReadXml(#"https://something.sharepoint.com/sites/pwa/_api/ProjectData/Projects");
var query2 = ReadXml(#"https://something.sharepoint.com/sites/pwa/_api/ProjectData/Tasks");
Task.WaitAll(query1, query2);
If I "await" the first one and then do the second one it works fine, but not with the code above. And this is assuming there is < 300 tasks in the project, if more than that I have to query them in chunk of 300 leading to 4 or 5 seconds for the entire query since I can't to them all at once!
Is there a way to send multiple request at the same time ?
I am able to do it by simply entering the url in multiple chrome tabs really fast / have faster responses. I don't understand why it doesn't work with my code!
Thanks,
According to the following post Webrequest.Create could be the problem, it uses an internally blocking method C# Thread UI is getting blocked | Possible reason WebRequest.Create?.
The code below uses the newer HttpClient and shouldn't have this issue.
public static HttpClient _HttpClient { get; } = new HttpClient(new HttpClientHandler { Credentials=new NetworkCredential("","")});
public static async Task<string> ReadXml(string url)
{
using (var requestMessage = new HttpRequestMessage(HttpMethod.Get, url))
{
requestMessage.Headers.Add("X-FORMS_BASED_AUTH_ACCEPTED", "f");
using (var response = await _HttpClient.SendAsync(requestMessage))
{
return await response.Content.ReadAsStringAsync();
}
}
}
I am beginner and creating winform application. In which i have to use API for Simple CRUD operation. My client had shared API with me and asked to send data in form of JSON.
API : http://blabla.com/blabla/api/login-valida
KEY : "HelloWorld"
Value : { "email": "user#gmail.com","password": "123456","time": "2015-09-22 10:15:20"}
Response : Login_id
How can i convert data to JSON, call API using POST method and get response?
EDIT
Somewhere on stackoverflow i found this solution
public static void POST(string url, string jsonContent)
{
url="blabla.com/api/blala" + url;
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(baseURL);
request.Method = "POST";
System.Text.UTF8Encoding encoding = new System.Text.UTF8Encoding();
Byte[] byteArray = encoding.GetBytes(jsonContent);
request.ContentLength = byteArray.Length;
request.ContentType = #"application/json";
using (Stream dataStream = request.GetRequestStream())
{
dataStream.Write(byteArray, 0, byteArray.Length);
}
long length = 0;
try
{
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
{
length = response.ContentLength;
}
}
catch
{
throw;
}
}
//on my login button click
private void btnLogin_Click(object sender, EventArgs e)
{
CallAPI.POST("login-validate", "{ \"email\":" + txtUserName.Text + " ,\"password\":" + txtPassword.Text + ",\"time\": " + DateTime.Now.ToString("yyyy-MM-dd h:mm tt") + "}");
}
I got exception that says "The remote server returned an error: (404) Not Found."
You can take a look at the following docs tutorial:
Call a Web API From a .NET Client
But as an answer, here I will share a quick and short a step by step guide about how to call and consume web API in Windows forms:
Install Package - Install the Microsoft.AspNet.WebApi.Client NuGet package (Web API Client Libraries).
Open Tools menu → NuGet Package Manager → Package Manager Console → In the Package Manager Console window, type the following command:
Install-Package Microsoft.AspNet.WebApi.Client
You can install package by right click on project and choosing Manage NuGet Packages as well.
Set up HttpClient - Create an instance of HttpClient and set up its BaseAddress and DefaultRequestHeaders. For example:
// In the class
static HttpClient client = new HttpClient();
// Put the following code where you want to initialize the class
// It can be the static constructor or a one-time initializer
client.BaseAddress = new Uri("http://localhost:4354/api/");
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(
new MediaTypeWithQualityHeaderValue("application/json"));
Send Request - To send the requests, you can use the following methods of the HttpClient:
GET: GetAsync, GetStringAsync, GetByteArrayAsync, GetStreamAsync
POST: PostAsync, PostAsJsonAsync, PostAsXmlAsync
PUT: PutAsync, PutAsJsonAsync, PutAsXmlAsync
DELETE: DeleteAsync
Another HTTP method: Send
Note: To set the URL of the request for the methods, keep in mind, since you have specified the base URL when you defined the client, then here for these methods, just pass path, route values and query strings, for example:
// Assuming http://localhost:4354/api/ as BaseAddress
var response = await client.GetAsync("products");
or
// Assuming http://localhost:4354/api/ as BaseAddress
var product = new Product() { Name = "P1", Price = 100, Category = "C1" };
var response = await client.PostAsJsonAsync("products", product);
Get the Response
To get the response, if you have used methods like GetStringAsync, then you have the response as string and it's enough to parse the response. If the response is a Json content which you know, you can easily use JsonConvert class of Newtonsoft.Json package to parse it. For example:
// Assuming http://localhost:4354/api/ as BaseAddress
var response = await client.GetStringAsync("product");
var data = JsonConvert.DeserializeObject<List<Product>>(response);
this.productBindingSource.DataSource = data;
If you have used methods like GetAsync or PostAsJsonAsync and you have an HttpResponseMessage then you can use ReadAsAsync, ReadAsByteArrayAsync, ReadAsStreamAsync, `ReadAsStringAsync, for example:
// Assuming http://localhost:4354/api/ as BaseAddress
var response = await client.GetAsync("products");
var data = await response.Content.ReadAsAsync<IEnumerable<Product>>();
this.productBindingSource.DataSource = data;
Performance Tip
HttpClient is a type that is meant to be created once and then shared. So don't try to put it in a using block every time that you want to use it. Instead, create an instance of the class and share it through a static member. To read more about this, take a look at Improper Instantiation antipattern
Design Tip
Try to avoid mixing the Web API related code with your application logic. For example let's say you have a product Web API service. Then to use it, first define an IProductServieClient interface, then as an implementation put all the WEB API logic inside the ProductWebAPIClientService which you implement to contain codes to interact with WEB API. Your application should rely on IProductServieClient. (SOLID Principles, Dependency Inversion).
Just use the following library.
https://www.nuget.org/packages/RestSharp
GitHub Project: https://github.com/restsharp/RestSharp
Sample Code::
public Customer GetCustomerDetailsByCustomerId(int id)
{
var client = new RestClient("http://localhost:3000/Api/GetCustomerDetailsByCustomerId/" + id);
var request = new RestRequest(Method.GET);
request.AddHeader("X-Token-Key", "dsds-sdsdsds-swrwerfd-dfdfd");
IRestResponse response = client.Execute(request);
var content = response.Content; // raw content as string
dynamic json = JsonConvert.DeserializeObject(content);
JObject customerObjJson = json.CustomerObj;
var customerObj = customerObjJson.ToObject<Customer>();
return customerObj;
}
Use Json.Net to convert data into JSON
Use WebClient to POST data
Use This code:
var client = new HttpClient();
client.BaseAddress = new Uri("http://www.mywebsite.com");
var request = new HttpRequestMessage(HttpMethod.Post, "/path/to/post/to");
var keyValues = new List<KeyValuePair<string, string>>();
keyValues.Add(new KeyValuePair<string, string>("site", "http://www.google.com"));
keyValues.Add(new KeyValuePair<string, string>("content", "This is some content"));
request.Content = new FormUrlEncodedContent(keyValues);
var response = await client.SendAsync(request);
Here is another example using an online REST service (https://northwind.vercel.app) which allows interaction with Northwind API.
This example uses HttpClient and JsonConvert to get or post data. Here is a very quick example:
Install Newtonsoft.Json nuget package. And add the following using statements to your form:
using System.Net.Http;
using Newtonsoft.Json
Define an instance of the HttpClient, at class level:
private static HttpClient client = new HttpClient();
To send a GET request, for example getting list of all data:
var url = "https://northwind.vercel.app/api/categories";
var response = await client.GetAsync(url);
if (response.StatusCode == System.Net.HttpStatusCode.OK)
{
var content = await response.Content.ReadAsStringAsync();
var categories = JsonConvert.DeserializeObject<List<Category>>(content);
dataGridView1.DataSource = categories;
}
You can also use other overloads of Get, like GetStringAsync, GetStreamAsync, and etc. But GetAsync is a more generic method allowing you to get the status code as well.
To send a POST request, for example posting a new data:
var url = "https://northwind.vercel.app/api/categories";
var data = new Category() { Name = "Lorem", Description = "Ipsum" };
var jsonData = Newtonsoft.Json.JsonConvert.SerializeObject(data);
var requestContent = new StringContent(jsonData, Encoding.Unicode, "application/json");
var response = await client.PostAsync(url, requestContent);
if (response.StatusCode == System.Net.HttpStatusCode.Created)
{
var content = await response.Content.ReadAsStringAsync();
var createdCategory = JsonConvert.DeserializeObject<Category>(content);
MessageBox.Show(createdCategory.Id.ToString())
}
To learn more and see some best practices or see an example without JsonConvert, see my other post.
I am using Microsoft.AspNet.WebApi.Client to consume rest services in my ASP.MVC 5 project. I am following the this tutorial to make use of HttpClient. The code is not compiling since ReadAsAsync method is no longer available in HttpContent. After digging a bit I came to know that it is an extension method defined in System.Net.Http.Formatting.dll. I found a nuget package for the same dll here but the package is deprecated and I am not able to install it. I also trid to search that dll in Program Files folder according to this post but I could not get it. Any ideas how to make ReadAsAsync work? Any help greatly appreiciated. Thanks.
What do you need to do is to add new reference System.Net.HttpClient; and System.Net.HttpClient.Formating;.
This is my sample codes in HttpClient:
The following codes is use to get a certificate from saba using HttpClient.
using System.Net.Http;
using System.Net.Http.Headers;
using GoSaba.Models.Saba;
namespace GoSaba.Controllers.Saba
{
class LoginController
{
//HTTP GET: Saba/api/login
public async Task<string> GetCertificate(string host, string user, string password, string site)
{
StringBuilder getCertificate = new StringBuilder();
if(!string.IsNullOrEmpty(host))
{
using(var httpClient = new HttpClient())
{
httpClient.BaseAddress = new Uri(string.Format("http://{0}/", host));
httpClient.DefaultRequestHeaders.Accept.Clear();
httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
httpClient.DefaultRequestHeaders.Add("user", user);
httpClient.DefaultRequestHeaders.Add("password", password);
httpClient.DefaultRequestHeaders.Add("site", site);
HttpResponseMessage httpResponse = await httpClient.GetAsync("Saba/api/login");
if(httpResponse.IsSuccessStatusCode)
{
LoginModel.GetCertificate saba = await httpResponse.Content.ReadAsAsync<LoginModel.GetCertificate>();//LoginModel.GetCertificate is model.
getCertificate.Append(saba.certificate);
}
}
}
return getCertificate.ToString();
}
}
}
You can use this a reference in how to use a HttpClient.
Here is an alternate way using the same Microsoft.AspNet.WebApi.Client. The number of lines of code increase but you wont find any issue like Newtonsoft version issue, which prompted me to look at alternatives for ReadAsAsync.
Here is a link that explains the code - https://www.newtonsoft.com/json/help/html/Performance.htm
HttpClient client = new HttpClient();
using (Stream s = client.GetStreamAsync("http://www.test.com/large.json").Result)
using (StreamReader sr = new StreamReader(s))
using (JsonReader reader = new JsonTextReader(sr))
{
JsonSerializer serializer = new JsonSerializer();
// read the json from a stream
// json size doesn't matter because only a small piece is read at a time from the HTTP request
T p = serializer.Deserialize<T>(reader); // Where T is any type
}
I want to code an auto bot for an online game (tribalwars.net). I'm learning C# in school, but haven't covered networking yet.
Is it possible to make HTTP POSTs though C#? Can anyone provide an example?
Trivial with System.Net.WebClient:
using(WebClient client = new WebClient()) {
string responseString = client.UploadString(address, requestString);
}
There is also:
UploadData - binary (byte[])
UploadFile - from a file
UploadValues - name/value pairs (like a form)
You can use System.Net.HttpWebRequest:
Request
HttpWebRequest request= (HttpWebRequest)WebRequest.Create(url);
request.ContentType="application/x-www-form-urlencoded";
request.Method = "POST";
request.KeepAlive = true;
using (Stream requestStream = request.GetRequestStream())
{
requestStream.Write(BytePost,0,BytePost.Length);
requestStream.Close();
}
Response
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
using(StreamReader sr = new StreamReader(response.GetResponseStream()))
{
responseString = sr.ReadToEnd();
}
Here's a good example. You want to use the WebRequest class in C#, which will make this easy.
I understand this is old question, but posting this for someone looking for quick example on how to send Http Post request with json body in latest .NET (Core 5), using HttpClient (part of System.Net.Http namespace). Example:
//Initialise httpClient, preferably static in some common or util class.
public class Common
{
public static HttpClient HttpClient => new HttpClient
{
BaseAddress = new Uri("https://example.com")
};
}
public class User
{
//Function, where you want to post data to api
public void CreateUser(User user)
{
try
{
//Set path to api
var apiUrl = "/api/users";
//Initialize Json body to be sent with request. Import namespaces Newtonsoft.Json and Newtonsoft.Json.Linq, to use JsonConvert and JObject.
var jObj = JObject.Parse(JsonConvert.SerializeObject(user));
var jsonBody = new StringContent(jObj.ToString(), Encoding.UTF8, "application/json");
//Initialize the http request message, and attach json body to it
var request = new HttpRequestMessage(HttpMethod.Post, apiUrl)
{
Content = jsonBody
};
// If you want to send headers like auth token, keys, etc then attach it to request header
var apiKey = "qwerty";
request.Headers.Add("api-key", apiKey);
//Get the response
using var response = Common.HttpClient.Send(request);
//EnsureSuccessStatusCode() checks if response is successful, else will throw an exception
response.EnsureSuccessStatusCode();
}
catch (System.Exception ex)
{
//handle exception
}
}
}
Why is HttpClient static or recommended to be instantiated once per application:
HttpClient is intended to be instantiated once and re-used throughout
the life of an application. Instantiating an HttpClient class for
every request will exhaust the number of sockets available under heavy
loads. This will result in SocketException errors.
HttpClient class has async methods too. More info on HttpClient class: https://learn.microsoft.com/en-us/dotnet/api/system.net.http.httpclient?view=net-5.0