Custom Data Provider

When using an uncontrolled environment, you need to provide your data by supplying a data provider. This provider must implement the TreeDataProvider interface, i.e.

export interface TreeDataProvider<T = any> {
  onDidChangeTreeData?: (listener: (changedItemIds: TreeItemIndex[]) => void) => Disposable;
  getTreeItem: (itemId: TreeItemIndex) => Promise<TreeItem<T>>;
  getTreeItems?: (itemIds: TreeItemIndex[]) => Promise<TreeItem[]>;
  onRenameItem?: (item: TreeItem<T>, name: string) => Promise<void>;
  onChangeItemChildren?: (itemId: TreeItemIndex, newChildren: TreeItemIndex[]) => Promise<void>;
}

At least the getTreeItem method must be implemented, to declare how data can be made available to the tree structure. getTreeItems allows you to make loading more efficient if multiple entries need to be loaded at once. If you do not implement getTreeItems, they are loaded sequentially using getTreeItem.

The methods onRenameItem and onChangeItemChildren allow you to declare how updates to the tree structure should be handled, i.e. by renaming an item or moving items from one parent to another. You still need to enable this functionality in the environment by providing the respective flags. Look into the TreeCapabilities interface for more details on the necessary flags.