Setting node name keeps tree linkage

datatree/tests/test_datatree.py

@@ -68,6 +68,23 @@ def test_child_gets_named_on_attach(self):
         mary = DataTree(children={"Sue": sue})  # noqa
         assert sue.name == "Sue"
 
+    def test_setting_node_name_keeps_tree_linkage(self):
+        root = DataTree(name="root")
+        child = DataTree(name="child", parent=root)
+        grandchild = DataTree(name="grandchild", parent=child)
+
+        assert root.name == "root"
+        assert child.name == "child"
+        assert grandchild.name == "grandchild"
+
+        # changing the name of a child node should correctly update the dict key in
+        # its parent's children
+        child.name = "childish"
+
+        assert child.name == "childish"
+        assert "childish" in root
+        assert list(root.children) == ["childish"]
+
 
 class TestPaths:
     def test_path_property(self):

datatree/treenode.py

@@ -91,7 +91,7 @@ def parent(self) -> Tree | None:
         return self._parent
 
     def _set_parent(
-        self, new_parent: Tree | None, child_name: Optional[str] = None
+        self, new_parent: Tree | None, child_name: str | None = None
     ) -> None:
         # TODO is it possible to refactor in a way that removes this private method?
 
@@ -601,15 +601,18 @@ def name(self, name: str | None) -> None:
                 raise TypeError("node name must be a string or None")
             if "/" in name:
                 raise ValueError("node names cannot contain forward slashes")
+        parent = self._parent
+        self.orphan()
         self._name = name
+        self._set_parent(parent, name)
 
     def __str__(self) -> str:
         return f"NamedNode({self.name})" if self.name else "NamedNode()"
 
     def _post_attach(self: NamedNode, parent: NamedNode) -> None:
         """Ensures child has name attribute corresponding to key under which it has been stored."""
         key = next(k for k, v in parent.children.items() if v is self)
-        self.name = key
+        self._name = key
 
     @property
     def path(self) -> str:

docs/source/whats-new.rst

@@ -45,6 +45,10 @@ Deprecations
 
 Bug fixes
 ~~~~~~~~~
+
+- Renaming a node also update the key of its parent's children
+  (:issue:`309`, :pull:`310`)
+  By `Etienne Schalk <https://github.com/etienneschalk>`_.
 - Keep attributes on nodes containing no data in :py:func:`map_over_subtree`. (:issue:`278`, :pull:`279`)
   By `Sam Levang <https://github.com/slevang>`_.