Mat-tree :Tree with nested nodes adding child doesnt update the view.

[juggernut]

Bug:

When using mat-nested-tree-node with a nested datasource if you add a child to an existing parent it does not update the view.

What is the expected behavior?

Well if you change or add a child to an existing parent in the nestedDataSource it should update the tree.

What is the current behavior?

It does not update the view when adding a child to an existing parent to the nestedDataStructure .

What is the use-case or motivation for changing an existing behavior?

Well in my case i need to update the view since i add/delete nodes .

Which versions of Angular, Material, OS, TypeScript, browsers are affected?

versions 6 (Chrome ver 66)

Is there anything else we should know?

I found an workaround:
refreshTree(){
let _data = this.nestedDataSource.data;
this.nestedDataSource.data = null;
this.nestedDataSource.data = _data;
}

[josephperrott]

Can you please provide a reproduction in stackblitz

[wojiusihshen1]

I have met the same issue. Could anyone please help confirm whether its a bug?

this.dataChange.next(data);

When update with new object ( e.g data = [] or a new instance), it works.
When push/update 'data' object, tree view will not be re render, though this.nestedDataSource.data already updated.

[juggernut]

I think is a bug since it works in one case but not in the other one ! Feel free to use my workaround , meanwhile 👍 .

refreshTree(){
let _data = this.nestedDataSource.data;
this.nestedDataSource.data = null;
this.nestedDataSource.data = _data;
}

[tech-no-logical]

I think the cdk-tree (the basis of mat-tree) has the same issue, see here:

https://stackblitz.com/edit/cdk-nested-tree?file=src%2Fapp%2Fmytree%2Fmytree.component.ts

clicking the 'add' button should push a new node onto the children array. console shows it does, but the tree is not updated.

[dodgeviper]

it also does not update the tree node, if we update the node.
https://stackblitz.com/angular/onaqbrpjaan
saving a new label to the node does not update the tree.

[quanterion]

Have the same issue. Any updates?

[jamadou]

I've had the same issue.
Appears that binding and UI reflecting works only for the first layer of the tree nodes, but not for any nodes down further. Glad to see there is a workaround, thanks to @juggernut

[nvuhung]

Any updates for this? I must use refresh method from @juggernut to refresh the datasource

[zhaodong-wang]

@juggernut's fix seems only work for the data source but treeControl still fails, the toggle doesn't work after updating the data.

[SirZach]

Closed because it was fixed? If we have to use the workaround it should be documented before the issue is closed, right?