Theia doesn't seem to be listening to tree view refresh event

[drochgenius]

I have a Visual Studio Code extension when I contributed Tree Views. For context, it's a custom tree view that fetches its data from a server, it is not a file browser.

I've also implemented a button to refresh the tree view according to the VSCode extenstion docs: https://code.visualstudio.com/api/extension-guides/tree-view#updating-tree-view-content

I checked on the Theia compatibility table that the function onDidChangeTreeData is supported: https://eclipse-theia.github.io/vscode-theia-comparator/status.html.

I found the associated code that handles this in Theia:

theia/packages/plugin-ext/src/plugin/tree/tree-views.ts

Line 255 in 3a714cb

options.treeDataProvider.onDidChangeTreeData?.(elements => {

However, when I fire the event on the EventEmitter, Theia doesn't seem to be listening.
The event is fired and nothing happens.

I am unable to have the content of my tree view re-fetched from the server when needed. As a result, my users have to reload their browsers.

This is an excerpt of my implementation:

export class TreeDataProvider implements ITreeDataProvider {
    private onDidChangeTreeDataEmitter: vscode.EventEmitter<TreeNode | undefined | null | void> = new vscode.EventEmitter<TreeNode | undefined | null | void>();
  	readonly onDidChangeTreeData: vscode.Event<TreeNode | undefined | null | void> = this.onDidChangeTreeDataEmitter.event;

    public refresh(treeNode?: TreeNode): void {
        if (treeNode && this.treeNodesMap[treeNode.node.id] === treeNode) {
            treeNode.dirty = true;
            this.onDidChangeTreeDataEmitter.fire(treeNode);
        } else {
            this.onDidChangeTreeDataEmitter.fire();
        }
    }

When fire() is called, no one is listening.

Am I missing something?

[msujew]

cc @tsmaeder

[msujew]

@drochgenius Which Theia version are you using? We introduced a bug in 1.58 that was fixed in 1.59, see #14868.

[drochgenius]

I am on Theia 1.58, I will update to 1.59.

[drochgenius]

Doesn't work on Theia 1.59.
All I know is that fire() method is being called, but I am not sure if the event is actually fired and caught by Theia.

I will put together a simple example.

[drochgenius]

I am running Theia 1.59 now with my plugin, and I was able to confirm that when I fire the event, it's actually properly caught by Theia.

• The onDidChangeTreeData listener is called.
• Since elements is undefined, it calls this line, and it has the proper treeViewId value.
• If I monitor the this.pendingRefresh promise, it eventually resolved successfully after a few milliseconds (~25ms).
• As expected, I see the getChildren() method of my TreeDataProvider is properly called on refresh.

Only there is no visible changes in the Tree View after refresh, but I assume it's because the tree view is already up to date.

When I go back to Theia 1.58, it is not working.
So this confirms that this was a bug in Theia 1.58, and that it is fixed in Theia 1.59.

Thanks for your help

[drochgenius]

We had to rollback to Theia 1.58.
The server run out of memory on Theia 1.59.
#15396