[Question] What is the best way to implement filtering of child elements in TreeDataGrid?

[asmirnov82]

Hi.

I am using TreeDataGrid to show 2 level hierarchy and I would like to implement filtering: show children that starts with user defined substring('SearchText'). Filtering should happen dynamically (while user enters search text - the amount of shown items should decrease to show only child elements that satisfy already typed text). What is the best way to implement this functionality?

I came up to a solution (not working) with defining filtering inside childSelector of HierarchicalExpanderColumn:

ItemSource = new HierarchicalTreeDataGridSource<TreeItemNode>(Items)
{
    Columns =
    {
        new HierarchicalExpanderColumn<TreeItemNode>(new TextColumn<TreeItemNode, string>("Items", x => x.Name, width: new GridLength(1, GridUnitType.Star)),
        x => x.Children?.Where(child => string.IsNullOrEmpty(SearchText) || child.Name.StartsWith(SearchText)))
    }
};

...
internal class TreeItemNode : ObservableObject
{
    public string Name { get; init; }
    
    public IReadOnlyCollection<TreeItemNode>? Children { get; init; }

    public TreeItemNode(string name, TreeItemNode[]? children = null)
    {
        Name = name;
        Children = children;
    }
}

However, this requires all nodes to be collapsed/expanded for recalculation, that doesn't suite my needs. Could you please suggest a better approach or a way to force TreeDataGrid to refresh it's content?