I'm trying to POST data to server and get the response to bind it to a Long List Selector. This is the code :
public class TestData
{
private string _LikeNum, _CommentNum, _HyperLinkTitle, _HyperLinkNavigationLink, _BrandImage, _PostImage, _PostDate, _PostTitle, _PostDescription, _PostID;
public string LikeNum { get { return _LikeNum; } set { _LikeNum = value; } }
public string CommentNum { get { return _CommentNum; } set { _CommentNum = value; } }
public string HyperLinkTitle { get { return _HyperLinkTitle; } set { _HyperLinkTitle = value; } }
public string HyperLinkNavigationLink { get { return _HyperLinkNavigationLink; } set { _HyperLinkNavigationLink = value; } }
public string BrandImage { get { return _BrandImage; } set { _BrandImage = value; } }
public string PostImage { get { return _PostImage; } set { _PostImage = value; } }
public string PostDate { get { return _PostDate; } set { _PostDate = value; } }
public string PostTitle { get { return _PostTitle; } set { _PostTitle = value; } }
public string PostDescription { get { return _PostDescription; } set { _PostDescription = value; } }
public string PostID { get { return _PostID; } set { _PostID = value; } }
public TestData(string LNum, string CNum, string HLTitle, string HLNaviagtionLink, string BImage, string PImage, string PDate, string PTitle, string PDescription, string PID)
{
this.LikeNum = LNum;
this.CommentNum = CNum;
this.HyperLinkTitle = HLTitle;
this.HyperLinkNavigationLink = HLNaviagtionLink;
this.BrandImage = BImage;
this.PostImage = PImage;
this.PostDate = PDate;
this.PostTitle = PTitle;
this.PostDescription = PDescription;
this.PostID = PID;
}
}
#region Lists of data
List<string> LstBrandID = new List<string>();
List<string> LstBrandName = new List<string>();
List<string> LstBrandLongitude = new List<string>();
List<string> LstBrandLatitude = new List<string>();
List<string> LstPostID = new List<string>();
List<string> LstPostTitle = new List<string>();
List<string> LstPostDescription = new List<string>();
List<string> LstPostDate = new List<string>();
List<string> LstLikeNum = new List<string>();
List<string> LstCommentNum = new List<string>();
List<string> LstUserLike = new List<string>();
List<string> LstCatName = new List<string>();
List<string> LstUserFollow = new List<string>();
#endregion
ObservableCollection<TestData> DataList = new ObservableCollection<TestData>();
string id;
public Home()
{
InitializeComponent();
id = PhoneApplicationService.Current.State["id"].ToString();
try
{
GetPosts(id);
myLLS.ItemsSource = DataList;
for (int i = 1; i <= 10; i++)
{
DataList.Add(new TestData(LstLikeNum[i], LstCommentNum[i], LstBrandName[i], "SomePage.xaml", "SomeLink.com/data/" + LstBrandID[i], "SomeLink.com/data/" + LstPostID[i], LstPostDate[i], LstPostTitle[i], LstPostDescription[i], LstPostID[i]));
}
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
throw;
}
}
#region getting data
void GetPosts(string UserID)
{
WebClient webclient = new WebClient();
Uri uristring = new Uri("SomeLink.com");
webclient.Headers["Content-Type"] = "application/x-www-form-urlencoded";
string postJsonData = string.Empty;
postJsonData += "userId=" + UserID;
webclient.UploadStringAsync(uristring, "POST", postJsonData);
webclient.UploadStringCompleted += webclient_UploadStringCompleted;
}
void webclient_UploadStringCompleted(object sender, UploadStringCompletedEventArgs e)
{
try
{
if (e.Result != null)
{
string response = e.Result.ToString();
JArray a = JArray.Parse(response);
foreach (JObject o in a.Children<JObject>())
{
foreach (JProperty p in o.Properties())
{
string name = p.Name;
string value = p.Value.ToString();
if (name == "brandId")
{
LstBrandID.Add(value);
}
else if (name == "brandName")
{
LstBrandName.Add(value);
}
else if (name == "brandLongitude")
{
LstBrandLongitude.Add(value);
}
else if (name == "brandLatitude")
{
LstBrandLatitude.Add(value);
}
else if (name == "postId")
{
LstPostID.Add(value);
}
else if (name == "postTitle")
{
LstPostTitle.Add(value);
}
else if (name == "postDescription")
{
LstPostDescription.Add(value);
}
else if (name == "postDate")
{
LstPostDate.Add(value);
}
else if (name == "likeNum")
{
LstLikeNum.Add(value);
}
else if (name == "commentNum")
{
LstCommentNum.Add(value);
}
else if (name == "userLike")
{
LstUserLike.Add(value);
}
else if (name == "catName")
{
LstCatName.Add(value);
}
else if (name == "userFollow")
{
LstUserFollow.Add(value);
}
}
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
#endregion
When I run the application I get Out Of Range Exception Getting data isn't the problem. The problem is the time it takes to get data from server to bind it to the Long List Selector. So, how can I delay the binding tell I get the data from the server and fill the Lists with them ?
In your Home():
myLLS.ItemsSource = DataList;
is good. You are telling your LLS to watch this data source and update itself whenever a new item is inserted.
for (int i = 1; i <= 10; i++)
{
DataList.Add(new TestData(LstLikeNum[i], LstCommentNum[i], LstBrandName ...);
}
is not good. You are trying to populate your data source before the data arrived. This is the operation that belongs in your request's callback. You're getting an out of range exception because LstLikeNum has 0 items, and you're trying to get items 0 -> 9.
Instead, do this:
void webclient_UploadStringCompleted(object sender, UploadStringCompletedEventArgs e) {
...
int i = 0;
foreach (JObject o in a.Children<JObject>())
{
foreach (JProperty p in o.Properties())
{
...
}
var testData = new TestData(LstLikeNum[i], LstCommentNum[i], ...);
DataList.Add(testData);
i++;
}
}
Note that you don't need to bind (myLLS.ItemsSource = DataList) in the callback. That's something you only do once -- the callback is only adding items to the source.