HttpClient ReadAsAsync does not deserialize

Question

I am not sure if the issue I am having is related to the way I'm using Task or if I am an not using ReadAsAsync correctly. I am following the pattern I found here:

http://blogs.msdn.com/b/henrikn/archive/2012/02/11/httpclient-is-here.aspx

Background: Object I am deserializing is a POCO. Properties have no attributes. It is just a few value type properties and a couple collection properties. REST service appears to work ok also. When I look at the JSON returned by the service it appears to be OK. Using Web API 2.1 5.1.2

Problem: .. is calling HttpResponseMessage.Content.ReadAsAsync(). Sometimes it works (returns an object) and sometimes it doesn't (throws "Thread was being aborted" or returns null). It appears the content property can be read once only and subsequent reads throw errors. See comments in code below.

Related questions: HttpContent.ReadAsAsync Deserialization issue

Question appears to be similar to mine. Answer indicates a bug but this is over two years old.

Code:

[TestMethod]
    public void AddSiteTest()
    {
        // Use POST to create a resource i.e. insert.  Use PUT to update.

        Site site = new Site {SiteName = "Test", Active = true, URI="www.test.com" };
        Site newSite = null;

        client.PostAsJsonAsync<Site>(baseURI + "/Sites/AddSite?securityKey="+ SecurityKey, site).ContinueWith(x =>
            {
                HttpResponseMessage response = x.Result;

                response.EnsureSuccessStatusCode();

                if (response.IsSuccessStatusCode)
                {
                    try
                    {

                        string str = Task.Run(() => response.Content.ReadAsStringAsync()).Result;      // yep its json and it is a proprety serialized object

                        // Method 1 (preferred... ):
                        //Site siteA = Task.Run(() => response.Content.ReadAsAsync<Site>()).Result;      // usuallly throws if content has been read  


                        // Method 2:
                        Site siteB = response.Content.ReadAsAsync<Site>().Result;                      // usully returns a valid result (when I dont put a breakpoint on it). Does not deadlock.

                        // Method 3:
                        response.Content.ReadAsAsync<Site>().ContinueWith(d => 
                        {
                            Site siteC = d.Result;                                                    // returns null
                        });

                    }
                    catch (Exception ex)
                    {
                        string y = ex.Message;
                    }
                }
            });
    }

Your continuations are probably running *after* the request has completed. Consider using async/await instead of `.ContinueWith` — spender, Jul 20 '14 at 01:02

score 0 · Answer 1 · answered Jul 20 '14 at 17:01

0

try to use await:

string str = await response.Content.ReadAsStringAsync();

And you have to add async before void in your method.

answered Jul 20 '14 at 17:01

user3224222

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I don't want to use an async test method. The method that runs this in production is not async. Async propagates itself all the way up the call stack. How do I call this method and wait? – Jul 20 '14 at 17:51

HttpClient ReadAsAsync does not deserialize

1 Answers1