Question

I got a Windows Phone project which are getting an list of a object that i call friend from an webservice using REST. The whole connection part works good the first time, the second time it fails. I get the same value from the method even tho i change the value in the database. Here is an example.

• Users goes to an page
• The right value is fetched from the database using an WCF service
• I change the value in the database manually
• User goes into the page again and the method for fetching the data is started again but it still gets the same result as the first time it fetched data from the webservice.

Any ideas?

Code:

    HttpWebRequest request;

    protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e) 
    {
        UpdateData();
    }

    public void UpdateData()
    {
        ((App)App.Current).ShowProgressBar();
        string uri = App.SERVICE_URI + "/GetFriends?userid=" + App.CurrentUserId;
        request = (HttpWebRequest)HttpWebRequest.Create(new Uri(uri));
        request.BeginGetResponse(new AsyncCallback(GetFriendsReadCallback), request);
    }

    private void GetFriendsReadCallback(IAsyncResult asynchronousResult)
    {
        List<Friend> friends;
        HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
        HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(asynchronousResult);
        using (StreamReader streamReader1 = new StreamReader(response.GetResponseStream()))
        {
            string resultString = streamReader1.ReadToEnd();
            var ser = new DataContractJsonSerializer(typeof(List<Friend>));
            var stream = new MemoryStream(Encoding.Unicode.GetBytes(resultString));
            DataContractJsonSerializer jsonSerializer = new DataContractJsonSerializer(typeof(List<Friend>));
            friends = (List<Friend>)jsonSerializer.ReadObject(stream);
        }

Answer 1

You are running into a caching issue, most likely. Either change your REST service to disable caching:

Response.Cache.SetCacheability(HttpCacheability.NoCache);

If you don’t have access to the service code, you can append a changing dummy parameter to the end of your request URL (e.g. a GUID or DateTime.Now.Ticks).

Check out my answer here: WebClient in a WP7.1 app called only once