How to send a Post body in the HttpClient request in Windows Phone 8?

Question

I have written the code below to send headers, post parameters. The problem is that I am using SendAsync since my request can be GET or POST. How can I add POST Body to this peice of code so that if there is any post body data it gets added in the request that I make and if its simple GET or POST without body it send the request that way. Please update the code below:

HttpClient client = new HttpClient();

// Add a new Request Message
HttpRequestMessage requestMessage = new HttpRequestMessage(RequestHTTPMethod, ToString());

// Add our custom headers
if (RequestHeader != null)
{
    foreach (var item in RequestHeader)
    {

        requestMessage.Headers.Add(item.Key, item.Value);

    }
}

// Add request body


// Send the request to the server
HttpResponseMessage response = await client.SendAsync(requestMessage);

// Get the response
responseString = await response.Content.ReadAsStringAsync();

Please see updated answer, it has a nicer approach. – Ilya Luzyanin Aug 06 '14 at 12:32 — Ilya Luzyanin, Aug 06 '14 at 12:32

score 147 · Accepted Answer · edited Jun 20 '20 at 09:12

147

This depends on what content do you have. You need to initialize your requestMessage.Content property with new HttpContent. For example:

...
// Add request body
if (isPostRequest)
{
    requestMessage.Content = new ByteArrayContent(content);
}
...

where content is your encoded content. You also should include correct Content-type header.

UPDATE:

Oh, it can be even nicer (from this answer):

requestMessage.Content = new StringContent("{\"name\":\"John Doe\",\"age\":33}", Encoding.UTF8, "application/json");

edited Jun 20 '20 at 09:12

Community

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answered Aug 06 '14 at 11:13

Ilya Luzyanin

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How to write a Json using a jsonSerializer into the content? – GiriB May 11 '18 at 12:10
11

@GiriB I use the Newtonsoft.Json package to do it like so: `requestMessage.Content = new StringContent(JsonConvert.SerializeObject(body), Encoding.UTF8, "application/json");` You could also use you JsonSerializer to serialize into a string as you might currently be doing, and then pass that string as the first parameter to the StringContent constructor. – Matt Shepherd Oct 19 '18 at 01:45

Adam Hey · Answer 2 · 2018-06-13T15:49:03.033

I implemented it in the following way. I wanted a generic MakeRequest method that could call my API and receive content for the body of the request - and also deserialise the response into the desired type. I create a Dictionary<string, string> object to house the content to be submitted, and then set the HttpRequestMessage Content property with it:

Generic method to call the API:

    private static T MakeRequest<T>(string httpMethod, string route, Dictionary<string, string> postParams = null)
    {
        using (var client = new HttpClient())
        {
            HttpRequestMessage requestMessage = new HttpRequestMessage(new HttpMethod(httpMethod), $"{_apiBaseUri}/{route}");

            if (postParams != null)
                requestMessage.Content = new FormUrlEncodedContent(postParams);   // This is where your content gets added to the request body


            HttpResponseMessage response = client.SendAsync(requestMessage).Result;

            string apiResponse = response.Content.ReadAsStringAsync().Result;
            try
            {
                // Attempt to deserialise the reponse to the desired type, otherwise throw an expetion with the response from the api.
                if (apiResponse != "")
                    return JsonConvert.DeserializeObject<T>(apiResponse);
                else
                    throw new Exception();
            }
            catch (Exception ex)
            {
                throw new Exception($"An error ocurred while calling the API. It responded with the following message: {response.StatusCode} {response.ReasonPhrase}");
            }
        }
    }

Call the method:

    public static CardInformation ValidateCard(string cardNumber, string country = "CAN")
    { 
        // Here you create your parameters to be added to the request content
        var postParams = new Dictionary<string, string> { { "cardNumber", cardNumber }, { "country", country } };
        // make a POST request to the "cards" endpoint and pass in the parameters
        return MakeRequest<CardInformation>("POST", "cards", postParams);
    }

Couple of problems with this implementation. First, it is not async. The use of ".Result" causes this to be a blocking call. Second problem is it doesn't scale! See my answer on why here - https://stackoverflow.com/questions/22560971/what-is-the-overhead-of-creating-a-new-httpclient-per-call-in-a-webapi-client/35045301#35045301 Third problem is you are throwing exceptions to handle control-flow. This is not a good practice. See - https://docs.microsoft.com/en-us/visualstudio/profiling/da0007-avoid-using-exceptions-for-control-flow?view=vs-2019 — Dave Black, Jun 24 '19 at 16:27

How to send a Post body in the HttpClient request in Windows Phone 8?

2 Answers2

UPDATE:

Linked