How to post data using HttpClient?

Question

I have got this HttpClient from Nuget.

When I want to get data I do it this way:

var response = await httpClient.GetAsync(url);
var data = await response.Content.ReadAsStringAsync();

But the problem is that I don't know how to post data? I have to send a post request and send these values inside it: comment="hello world" and questionId = 1. these can be a class's properties, I don't know.

Update I don't know how to add those values to HttpContent as post method needs it. httClient.Post(string, HttpContent);

Solution 1

You need to use:

await client.PostAsync(uri, content);

Something like that:

var comment = "hello world";
var questionId = 1;

var formContent = new FormUrlEncodedContent(new[]
{
    new KeyValuePair<string, string>("comment", comment), 
    new KeyValuePair<string, string>("questionId", questionId) 
});

var myHttpClient = new HttpClient();
var response = await myHttpClient.PostAsync(uri.ToString(), formContent);

And if you need to get the response after post, you should use:

var stringContent = await response.Content.ReadAsStringAsync();

Hope it helps ;)

Solution 2

Try to use this:

using (var handler = new HttpClientHandler() { CookieContainer = new CookieContainer() })
{
    using (var client = new HttpClient(handler) { BaseAddress = new Uri("site.com") })
    {
        //add parameters on request
        var body = new List<KeyValuePair<string, string>>
        {
            new KeyValuePair<string, string>("test", "test"),
            new KeyValuePair<string, string>("test1", "test1")
        };

        HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, "site.com");

        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/x-www-form-urlencoded; charset=UTF-8"));
        client.DefaultRequestHeaders.Add("Upgrade-Insecure-Requests", "1");
        client.DefaultRequestHeaders.Add("X-Requested-With", "XMLHttpRequest");
        client.DefaultRequestHeaders.Add("X-MicrosoftAjax", "Delta=true");
        //client.DefaultRequestHeaders.Add("Accept", "*/*");

        client.Timeout = TimeSpan.FromMilliseconds(10000);

        var res = await client.PostAsync("", new FormUrlEncodedContent(body));

        if (res.IsSuccessStatusCode)
        {
            var exec = await res.Content.ReadAsStringAsync();
            Console.WriteLine(exec);
        }                    
    }
}

Comments

[Patrick]

Did you try to use the Post method?

[Patrick]

You should follow the documentation for what content you should send in your post (if you are following an API). Then, just fill a HttpContent and use PostAsync did you try that?

[user2970840]

@Patrick thanks, I have updated my question

[Patrick]

Btw, posting comments 10 minutes after posting your question with "can't anyone help?" and a smiley face will probably not encourage other overflowers to help you faster. If you don't find anyone answering your question you might want to look at your question and see what you can do to improve it, with more information about what you tried, instead of expecting everyone else to guess what you know.

[user2970840]

@Patrick ok, I have updated it. please see if that is enough.

[RBT]

If someone is looking to upload a file using HttpClient - C# HttpClient 4.5 multipart/form-data upload

[user2970840]

thanks, but I think this HttpClient is better than WebClient. easier and cleaner. isn't it?

[user2970840]

response is Unprocessable entry. maybe I have a mistake somewhere else

[Lori Lalonde - MSFT]

Ah yes, I'm so used to WebClient, I had that in my head when I was reading the question. I haven't used HttpClient as of yet. Sorry!

[hkarask]

or shorter dictionary literal: var formContent = new FormUrlEncodedContent(new Dictionary<string, string> { {"comment", comment}, {"questionId", questionId } });

[ed22]

You may want to use MultipartFormDataContent instead of FormUrlEncodedContent (that depends on what your server expects)

[RBT]

Related post - POSTing JsonObject With HttpClient From Web API