[Extension Authoring] TreeDataProvider update doesn't cause update of collapsibleState of TreeItems

[rugpanov]

• VSCode Version: 1.25.0
• OS Version: Win10

Steps to Reproduce:

1. Create TreeDataProvider
2. Put a TreeItemCollapsibleState.Collapsed TreeItem there and save a ref to it
3. Fire TreeDataProvider#onDidChangeTreeData
Note: as expected now there is a collapsed TreeItem in the TreeDataProvider
4. Change collapsibleState of the TreeItem to the TreeItemCollapsibleState.Expanded via the stored ref
5. Fire TreeDataProvider#onDidChangeTreeData

Expected result: There is an expanded TreeItem in the TreeDataProvider
Actual result: There is a collapsed TreeItem in the TreeDataProvider

Note 1: It worked correctly in VSCode 1.24.0 but not in 1.25.0 for me
Note 2: changing collapsibleState in the UI still works.
Note 3: changing collapsibleState from TreeItemCollapsibleState.Expanded/Collapsed to TreeItemCollapsibleState.None works fine.

[vscodebot]

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

• Expose the collapsible state of the tree item (#30535)

[sandy081]

Duplicate of #30918

[vscodebot]

Thanks for creating this issue! We figured it's covering the same as another one we already have. Thus, we closed this one as a duplicate. You can search for existing issues here. See also our issue reporting guidelines.

Happy Coding!

[rugpanov]

@sandy081, are you sure this is the same issue?
One I reported is appeared after update from 1.24.0 to 1.25.0
And it has another description

[sandy081]

@rugpanov There was a similar issue before which is a dup of #30918.

Since you are mentioning it is working in previous release, I will check it.

[fabiospampinato]

I'm also having this problem.

I want to add a collapse/expand button to the navigation bar, but the only ways that I've found for actually collapsing/expanding the tree are:

1. Clearing it first, then rebuilding it collapsed/expanded
2. Change the labels by appending a random number of whitespace characters to them

The obvious solution would be just setting TreeItem.collapsibleState to something, which doesn't work.

[sandy081]

This is another issue related to shouldAutoexpand api from the tree which shares the same root cause of #30918.

@joaomoreno FYI

[sandy081]

If you want a node to be expanded or collapsed programatically, may be the right approach is to have an API to expand or collapse instead of causing a data change?

[fabiospampinato]

@sandy081 Why not both an API and listening for a mutation of the collapsibleState property? The "problem" with the API is that we would have to keep references to the TreeItems around.

[sandy081]

CollapsibleState is view state property and not data property. IMO it was wrongly placed and a method in the TreeView is the right place. Also, we do not want to provide same functionality as multiple APIs.

[rugpanov]

It used to work with collapsibleState property and some extension authors used it. So from this perspective it would be better to return this way. In any case - with separate API or with previous approach, now it doesn't work and for me this is a problem. Please could you provide a possibility to expand/collapse a collapsible tree item in the nearest release.

[sandy081]

@rugpanov It only works consistently if you give the state for the first time and was not working completely. See #30918

[rugpanov]

@sandy081 Now I see. So are there any plans about adding such a functionality? It would be really useful for an extension authoring.

[sandy081]

There are plans to add an API to expand/collapse - #55879

[johnspurlock]

.collapse was never added on the view, so it's currently impossible to collapse a single item! .reveal({expand:false}) does not work either.

For example, try to implement toggle-expansion-on-select behavior to mimic the built-in explorer. Can track the real state using onDid(Expand|Collapse)Element, but can only set a new state of expanded, using .reveal({expand:true}) - impossible to set collapsed. Any workarounds appreciated. : )

As mentioned earlier in this bug, updating an existing TreeItem's collapsibleState has no effect.

Current stable (1.31) and insiders (1.32).

Thanks!

[alexr00]

duplicate of #78970