zope.app.tree.node error in hasChildren()

[Dragos Petre]

The hasChildren() method of zope.app.tree.node.Node is returning True even when the Node's children are all filtered out. This causes the navigation macro to display an expansion symbol (+ or -) to the left of a folder whose items are filtered out but when expanded, no children are displayed (which is correct).

The below test case, if added to the test_node.py module in the zope.app.tree.tests package, exemplifies the issue (please note that the patch in https://bugs.launchpad.net/bugs/264614 should be applied to the test module first):

    def test_filter(self):
        #An empty filter would filter all content out
        empty_filter = FilterByObject()
        filtered_root=Node(self.root_obj,filter=empty_filter)
        children = [node.context for node in filtered_root.getChildNodes()]
        expected = []
        self.assertEqual(children,expected)
        self.failIf(filtered_root.hasChildren())

The test fails on the last assertion because the hasChildren() method delegates to the synonymous method of the adapter, which is NOT filter aware.

A rough way around it is to change the hasChildren() method in node.py to return the length of getChildNodes() if the Node object has a filter defined. More efficient ways could probably be implemented and any comment on it would be appreciated.

Best regards,
Dragos.