Get child by ID

src/textual/app.py

@@ -279,18 +279,18 @@ class App(DOMNode):
 
         return DOMQuery(self.view, selector)
 
-    def get_child(self, selector: str) -> DOMNode:
-        """Shorthand for self.view.get_child(selector: str)
+    def get_child(self, id: str) -> DOMNode:
+        """Shorthand for self.view.get_child(id: str)
         Returns the first child (immediate descendent) of this DOMNode
-        matching the selector.
+        with the given ID.
 
         Args:
-            selector (str): A CSS selector.
+            id (str): The ID of the node to search for.
 
         Returns:
-            DOMNode: The first child of this node which matches the selector.
+            DOMNode: The first child of this node with the specified ID.
         """
-        return self.view.get_child(selector)
+        return self.view.get_child(id)
 
     def update_styles(self) -> None:
         """Request update of styles.

src/textual/dom.py

@@ -12,8 +12,9 @@ from ._node_list import NodeList
 from .css._error_tools import friendly_list
 from .css.constants import VALID_DISPLAY, VALID_VISIBILITY
 from .css.errors import StyleValueError
-from .css.styles import Styles, RenderStyles
 from .css.parse import parse_declarations
+from .css.styles import Styles, RenderStyles
+from .css.query import NoMatchingNodesError
 from .message_pump import MessagePump
 
 if TYPE_CHECKING:
@@ -282,19 +283,19 @@ class DOMNode(MessagePump):
                 if node.children:
                     push(iter(node.children))
 
-    def get_child(self, selector: str) -> DOMNode:
-        """Return the first child (immediate descendent) of this DOMNode matching a selector.
+    def get_child(self, id: str) -> DOMNode:
+        """Return the first child (immediate descendent) of this node with the given ID.
 
         Args:
-            selector (str): A CSS selector.
+            id (str): The ID of the child.
 
         Returns:
-            DOMNode: The first child of this node which matches the selector.
+            DOMNode: The first child of this node with the ID.
         """
-        from .css.query import DOMQuery
-
-        query = DOMQuery(selector=selector, nodes=list(self.children))
-        return query.first()
+        for child in self.children:
+            if child.id == id:
+                return child
+        raise NoMatchingNodesError(f"No child found with id={id!r}")
 
     def query(self, selector: str | None = None) -> DOMQuery:
         """Get a DOM query.

tests/test_animator.py

@@ -169,7 +169,7 @@ def test_animatable():
     assert animate_test.bar.value == 50.0
 
 
-class TestAnimator(Animator):
+class MockAnimator(Animator):
     """A mock animator."""
 
     def __init__(self, *args) -> None:
@@ -187,7 +187,7 @@ class TestAnimator(Animator):
 def test_animator():
 
     target = Mock()
-    animator = TestAnimator(target)
+    animator = MockAnimator(target)
     animate_test = AnimateTest()
 
     # Animate attribute "foo" on animate_test to 100.0 in 10 seconds
@@ -226,7 +226,7 @@ def test_animator():
 def test_bound_animator():
 
     target = Mock()
-    animator = TestAnimator(target)
+    animator = MockAnimator(target)
     animate_test = AnimateTest()
 
     # Bind an animator so it animates attributes on the given object

tests/test_dom.py

@@ -29,12 +29,8 @@ def test_display_set_invalid_value():
 @pytest.fixture
 def parent():
     parent = DOMNode(id="parent")
-
     child1 = DOMNode(id="child1")
-    child1.add_class("foo")
     child2 = DOMNode(id="child2")
-    child2.add_class("bar")
-
     grandchild1 = DOMNode(id="grandchild1")
     child1.add_child(grandchild1)
 
@@ -45,17 +41,17 @@ def parent():
 
 
 def test_get_child_gets_first_child(parent):
-    child = parent.get_child(".foo")
+    child = parent.get_child(id="child1")
     assert child.id == "child1"
-    assert child.get_child("#grandchild1").id == "grandchild1"
-    assert parent.get_child(".bar").id == "child2"
+    assert child.get_child(id="grandchild1").id == "grandchild1"
+    assert parent.get_child(id="child2").id == "child2"
 
 
 def test_get_child_no_matching_child(parent):
     with pytest.raises(NoMatchingNodesError):
-        parent.get_child("#doesnt-exist")
+        parent.get_child(id="doesnt-exist")
 
 
 def test_get_child_only_immediate_descendents(parent):
     with pytest.raises(NoMatchingNodesError):
-        parent.get_child("#grandchild1")
+        parent.get_child(id="grandchild1")