Question 172201 in Azure Question posted in
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item Can Azure & Xamarin Forms Collection View prevent duplicate items?

In my Xamarin forms App, I am trying to get data from Azure cosmos db and display it in my collectionView.

I successfully get data from Cosmos db but when I am trying to display by searching I have duplicated data in my collectionview

Here is how I get data from cosmos db :

    public async static Task<List<MyUser>> GetUserList(string MyFriendName)
{



    MyFriendName = MyFriendName.ToLower();
  
    List<MyUser> UsersList = new List<MyUser>();

    string sql =  "SELECT TOP 25 * FROM  " + collectionId + " u WHERE CONTAINS(LOWER(u.username),'"+ MyFriendName+ "') ";

    QueryDefinition query = new QueryDefinition(sql);
    


    using (FeedIterator<MyUser> iterator = container.GetItemQueryIterator<MyUser>(
     queryDefinition: query,
     requestOptions: new QueryRequestOptions()
     {
         MaxItemCount = -1,

     }))

    {
       
        while (iterator.HasMoreResults)
        {
            FeedResponse<MyUser> result = await iterator.ReadNextAsync();

            UsersList.AddRange(result.Resource);


        }

        return UsersList;



    }




}

Here is how I prepare to show the data from cosmos db:

ObservableRangeCollection<MyCommunityModel> datasource;
MyCommunityModel CommunityUser;
async   Task<ObservableRangeCollection<MyCommunityModel>> OnPersonSearch(string MyFriendName)
{

    datasource.Clear();
    //get data from cosmos db function
    var UsersList =  await  UserManager.GetUserList(MyFriendName);


    foreach (var u in UsersList)
    {
        CommunityUser = new MyCommunityModel();

        CommunityUser.MyId = u.MyId;
        CommunityUser.Username = u.Username;
        datasource.Add(CommunityUser);
    }

    return datasource;

}

//Here is how I show data

void OnSearchCommunity(System.Object sender, Xamarin.Forms.TextChangedEventArgs e)
{

// show data

Device.BeginInvokeOnMainThread(async () =>
{
     MyCommunityCollectionList.ItemSizingStrategy = ItemSizingStrategy.MeasureFirstItem;
        //display data here 
        MyCommunityCollectionList.ItemsSource = await OnPersonSearch(searchTerm);

});
Tags:

2

Answers


  1. 0

    create api and call it

    public async Task<List<TodoItem>> RefreshDataAsync ()
{
  ...
  Uri uri = new Uri (string.Format (Constants.TodoItemsUrl, string.Empty));
  ...
  HttpResponseMessage response = await client.GetAsync (uri);
  if (response.IsSuccessStatusCode)
  {
      string content = await response.Content.ReadAsStringAsync ();
      Items = JsonSerializer.Deserialize<List<TodoItem>>(content, serializerOptions);
  }
  ...
}
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  2. 0
    • Put a breakpoint on line datasource.Clear();. When it stops there, continue. Does it get there a second time, before the data is displayed? That’s the only way I can see data getting doubled.

    If two calls interleave: clear – await – clear – await – fill – fill, the result after second call would be doubled data.

    • It would be safer to move that clear down, after the var UsersList = await … line. This avoids possibility of second call coming between clear and filling of data.
    var UsersList =  await  UserManager.GetUserList(MyFriendName);
datasource.Clear();
foreach ..
  datasource.Add ..
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