Allow to reveal an empty TreeView programmatically

[apupier]

Currently, it i possible to reveal/expand a TreeView only when there is an element in the TreeView. it is oputting revealing this element in the TreeView.

it would useful to be abel to expand the TreeView even when there are no elements in the Tree.

Use case:

• when testing FUSETOOLS2-205 - avoid infinite loop camel-tooling/vscode-camelk#291
• when writing a tutorial guiding users Add a command that opens a view by name redhat-developer/vscode-didact#4 (comment)

asked on StackOverflow https://stackoverflow.com/questions/59983711/how-to-programmatically-make-a-treeview-visible

[vscodebot]

(Experimental duplicate detection)
Thanks for submitting this issue. Please also check if it is already covered by an existing one, like:

• Support multiple levels in TreeView menu (#66232)
• Customize the contents of the display menu in TreeView if right click an item (#84766)

[vscodebot]

This feature request is now a candidate for our backlog. The community has 60 days to upvote the issue. If it receives 20 upvotes we will move it to our backlog. If not, we will close it. To learn more about how we handle feature requests, please see our documentation.

Happy Coding!

[vscodebot]

🙂 This feature request received a sufficient number of community upvotes and we moved it to our backlog. To learn more about how we handle feature requests, please see our documentation.

Happy Coding!

[alexr00]

Proposal is to allow the first parameter here to be undefined:

vscode/src/vs/vscode.proposed.d.ts

Lines 1042 to 1044 in e95c40c

	export interface TreeView<T> extends Disposable {
	reveal(element: T | undefined, options?: { select?: boolean, focus?: boolean, expand?: boolean | number }): Thenable<void>;
	}

[eamodio]

I think we should add a show method, rather than overloading reveal. This also aligns with WebviewViews which have:

show(preserveFocus?: boolean): void;

I also think we should add a hide method to both tree views and webview views (which has been requested). Which also better aligns with a show method as we use that on lots of other API objects.

[alexr00]

I think that could result in this pattern:

let element: T | undefined;
// ... element gets set to something
if (element) {
    tree.reveal(element);
} else {
    tree.show();
}

[eamodio]

It could, but imo that still feels more right to me. Also the reveal method has an options bag that while there is some overlap, feels strange to apply to the view itself. And I feel the alignment with WebviewViews is quite important as well.

[wandyezj]

I'd prefer to simply allow the reveal element to be undefined (as currently proposed).

A questionable alternative is to allow an overload to reveal that moves element to the options parameter.

 export interface TreeView<T> extends Disposable { 
 	reveal(options?: { element?: T, select?: boolean, focus?: boolean, expand?: boolean | number }): Thenable<void>; 
 } 

note: the issue with the overload is that it can clash with the existing reveal definition if the properties of T are a set or subset of the options properties, which while unlikely could be confusing.

Another option is a reveal overload without any arguments.

 export interface TreeView<T> extends Disposable { 
 	reveal(): Thenable<void>; 
 } 

I think a show / hide API might be better as a separate proposal.

[cweijan]

I tried to pass a null to reveal, it can switch the treeview normally, which has met my needs.

treeView.reveal(null)

[gar1t]

IMHO the overload of reveal is objectively wrong :) show() is established as the function name for this (if I read the OP correctly). It's used by most (if not all) of the other view-like components (webviews, terminal, channels, etc.)

To reveal an item inside a view is view specific, whereas to make the view itself visible is something that applies to any view at all. The fact that show() doesn't exist on the tree view, and does pervasively elsewhere, looks like an implementation oversight.

The options in reveal() show that reveal(null) is nonsensical. These are node specific.

[gar1t]

As a driver for this behavior, I want to implement a command that shows a custom tree view in the same way that any of the other views are shown. You can do this manually via View -> Open view... -> . This is the behavior that tree.show() should have IMO. This should not effect the current tree selection but merely show the view and put it into focus (same every other show view command).

[gar1t]

Lol, reveal(undefined) already seems to work as described above! (I'm running 1.68.1) It's not yet documented though :)

I propose that an alias of show() be added (I'm glad the behavior's at least now supported!)

[EhabY]

Indeed, a dedicated show() would be much better especially when using a tree view with type TreeView<SomeNode> then we cannot pass undefined/null. I would have to (falsely) make it TreeView<SomeNode | undefined> and deal with the non-existent undefined or hack Typescript and do treeView.reveal(undefined as unknown as SomeNode). Both options are not ideal..