Do not include child DOM in the payload if there is a parent DOM as well.

Author: adamghill

django_unicorn/static/unicorn/js/messageSender.js

@@ -136,7 +136,7 @@ export function send(component, callback) {
       component.hash = responseJson.hash;
 
       let parent = responseJson.parent || {};
-      const rerenderedComponent = responseJson.dom || {};
+      const rerenderedComponent = responseJson.dom || "";
       const partials = responseJson.partials || [];
       const { checksum } = responseJson;
 

django_unicorn/views/__init__.py

@@ -268,6 +268,8 @@ def _process_component_request(
         "checksum": generate_checksum(str(component_request.data)),
     }
 
+    render_not_modified = False
+
     if partial_doms:
         result.update({"partials": partial_doms})
     else:
@@ -277,13 +279,14 @@ def _process_component_request(
             component_request.hash == hash
             and (not return_data or not return_data.value)
             and not component.calls
-            # TODO: Have a strategy to determine when to return a 304 when a component
-            # has a parent by looking closer at their metadata
-            and not component.parent
         ):
-            raise RenderNotModified()
+            if not component.parent:
+                raise RenderNotModified()
+            else:
+                render_not_modified = True
 
-        # Make sure that partials with comments or blank lines before the root element only return the root element
+        # Make sure that partials with comments or blank lines before the root element
+        # only return the root element
         soup = BeautifulSoup(rendered_component, features="html.parser")
         rendered_component = str(get_root_element(soup))
 
@@ -342,6 +345,16 @@ def _process_component_request(
                 }
             )
 
+        if render_not_modified:
+            # TODO: Determine if all parents have not changed and return a 304 if
+            # that's the case
+            # i.e. render_not_modified = render_not_modified and (parent hash test)
+            pass
+
+        # If there is a parent dom and a child dom, remove the child dom because it is superfluous
+        if parent.get("dom") and result.get("dom"):
+            del result["dom"]
+
         parent_result.update({"parent": parent})
         component = parent_component
         parent_component = parent_component.parent

tests/views/message/test_hash.py

@@ -8,6 +8,12 @@
 
 
 class FakeComponentParent(UnicornView):
+    template_name = "templates/test_component_parent.html"
+
+    value: int = 0
+
+
+class FakeComponentParentWithValue(UnicornView):
     template_name = "templates/test_component_parent_with_value.html"
 
     value: int = 0
@@ -250,12 +256,14 @@ def test_message_hash_no_change_but_calls(client):
 
 def test_message_hash_no_change_but_parent(client):
     component_id = shortuuid.uuid()[:8]
-    component = FakeComponentParent(
+    component = FakeComponentParentWithValue(
         component_id=component_id,
-        component_name="tests.views.message.test_hash.FakeComponentParent",
+        component_name="tests.views.message.test_hash.FakeComponentParentWithValue",
     )
     component.render()
 
+    assert component.value == 0
+
     child = component.children[0]
     rendered_child_content = child.render()
     child_hash = generate_checksum(rendered_child_content)