Question

Below is the code currently I am using for grouping in listview. I am able to group records, but when user clicks on the button(AddNewCluster) to create new group with set of records I am unable to concatenate with the old records. The listview gets updated with the new group and records. But I need to show the user both the old and newly added group and records.

ListCollectionView collectionView;  

public Window1() 
{
    InitializeComponent();

    var clusters = new[] 
    {
        new Cluster { Name = "Front end" }, 
        new Cluster { Name = "Middle end" }, 
        new Cluster { Name = "Back end" }, 
    };    
    collectionView = new ListCollectionView(new[] 
    {
        new Server { Cluster = clusters[0], Name = "webshop1" }, 
        new Server { Cluster = clusters[0], Name = "webshop2" }, 
        new Server { Cluster = clusters[0], Name = "webshop3" }, 
        new Server { Cluster = clusters[0], Name = "webshop4" }, 
        new Server { Cluster = clusters[0], Name = "webshop5" }, 
        new Server { Cluster = clusters[0], Name = "webshop6" }, 
        new Server { Cluster = clusters[2], Name = "sql1" }, 
        new Server { Cluster = clusters[2], Name = "sql2" }, 
    });

    var groupDescription = new PropertyGroupDescription("Cluster.Name"); 
    // this foreach must at least add clusters that can't be  
    // derived from items - i.e. groups with no items in them  
    foreach (var cluster in clusters) 
    groupDescription.GroupNames.Add(cluster.Name);    
    collectionView.GroupDescriptions.Add(groupDescription);
    ServersList.ItemsSource = collectionView;    
    Clusters = groupDescription.GroupNames;
}
readonly ObservableCollection<object> Clusters; 

And here is the AddNewCluster_Click method:

void AddNewCluster_Click(object sender, RoutedEventArgs e) 
{
    Clusters.Add(NewClusterName.Text);

    var clusters = new[] 
    {
        new Cluster { Name = NewClusterName.Text }, 
    };

    collectionView = new ListCollectionView(new[] 
    {
        new Server { Name = "new server data" }, 
    });

    var groupDescription = new PropertyGroupDescription("Cluster.Name");  

    // this foreach must at least add clusters that can't be 

    // derived from items - i.e. groups with no items in them 

    foreach (var cluster in clusters) 
        groupDescription.GroupNames.Add(cluster.Name);

    collectionView.GroupDescriptions.Add(groupDescription);

    ServersList.ItemsSource = collectionView;

}

Answer 1

It’s a bit difficult to read the code, but as far as I can make out, you’re creating a new collection view, with a completely new collection, instead of adding the new item to the old collection.

You should add the new item to the old collection and call CollectionView.Refresh().