Improve patch application and add list insertion tests

Refactored Control patch logic to use path-based indexing for more accurate patch target resolution. Updated DiffBuilder to fix path handling in dataclass comparison. Added comprehensive tests for list insertions and updates in both frozen and in-place diff scenarios, improving coverage for control list operations.

Author: FeodorFitsner

packages/flet/lib/src/models/control.dart

@@ -305,43 +305,51 @@ class Control extends ChangeNotifier {
           "Patch must be a list with at least 2 elements: tree_index, operation");
     }
 
-    // build map of "to-be-patched" tree nodes
-    Map<int, PatchTarget> treeIndex = {};
-    buildTreeIndex(Control control, dynamic obj, List<dynamic> node) {
+    Map<int, List<dynamic>> pathIndex = {};
+
+    buildPathIndex(List<dynamic> node, List<dynamic> path) {
       // node[0] - index
       // node[1] - map of child properties or indexes
-      treeIndex[node[0]] =
-          PatchTarget(obj is Control ? obj.properties : obj, control);
+      pathIndex[node[0]] = path;
       if (node.length > 1 && node[1] is Map) {
         for (var entry in (node[1] as Map).entries) {
           // key - property name or list index
           // value - child node
-          dynamic child;
-          if (obj is Control) {
-            child = obj.properties[entry.key];
-          } else if (obj is Map) {
-            child = obj[entry.key];
-          } else if (obj is List) {
-            child = obj[entry.key];
-          }
-          if (child is Control) {
-            control = child;
-          }
-          buildTreeIndex(control, child, entry.value);
+          buildPathIndex(entry.value, [...path, entry.key]);
         }
       }
     }
 
-    buildTreeIndex(this, this, patch[0]);
-    //debugPrint("TREE INDEX: $treeIndex");
+    buildPathIndex(patch[0], []);
+
+    //debugPrint("PATH INDEX: $pathIndex");
+
+    getPatchTarget(int index) {
+      var path = pathIndex[index]!;
+      dynamic obj = this;
+      Control? control = this;
+      for (var p in path) {
+        if (obj is Control) {
+          obj = obj.properties[p];
+        } else if (obj is Map) {
+          obj = obj[p];
+        } else if (obj is List) {
+          obj = obj[p];
+        }
+        if (obj is Control) {
+          control = obj;
+        }
+      }
+      return PatchTarget(obj is Control ? obj.properties : obj, control!);
+    }
 
     // apply patch commands
     for (int i = 1; i < patch.length; i++) {
       var op = patch[i] as List<dynamic>;
       var opType = OperationType.fromInt(op[0]);
       if (opType == OperationType.replace) {
         // REPLACE
-        var node = treeIndex[op[1]]!;
+        var node = getPatchTarget(op[1]);
         var key = op[2];
         var value = op[3];
         node.obj[key] = _transformIfControl(value, node.control, backend);
@@ -353,7 +361,7 @@ class Control extends ChangeNotifier {
         }
       } else if (opType == OperationType.add) {
         // ADD
-        var node = treeIndex[op[1]]!;
+        var node = getPatchTarget(op[1]);
         var index = op[2];
         var value = op[3];
         if (node.obj is! List) {
@@ -366,7 +374,7 @@ class Control extends ChangeNotifier {
         }
       } else if (opType == OperationType.remove) {
         // REMOVE
-        var node = treeIndex[op[1]]!;
+        var node = getPatchTarget(op[1]);
         var index = op[2];
         if (node.obj is! List) {
           throw Exception("Remove operation can be applied to lists only: $op");
@@ -377,9 +385,9 @@ class Control extends ChangeNotifier {
         }
       } else if (opType == OperationType.move) {
         // MOVE
-        var fromNode = treeIndex[op[1]]!;
+        var fromNode = getPatchTarget(op[1]);
         var fromIndex = op[2];
-        var toNode = treeIndex[op[3]]!;
+        var toNode = getPatchTarget(op[3]);
         var toIndex = op[4];
         if (fromNode.obj is! List || toNode.obj is! List) {
           throw Exception("Move operation can be applied to lists only: $op");

sdk/python/packages/flet/src/flet/controls/object_patch.py

@@ -458,7 +458,7 @@ def _item_added(self, parent, path, key, item, item_key=None, frozen=False):
             ):
                 self._compare_dataclasses(
                     parent,
-                    op.location,
+                    _path_join(path, key),
                     src,
                     dst,
                     frozen,
@@ -515,7 +515,7 @@ def _item_removed(self, path, key, item, item_key=None, frozen=False):
             ):
                 self._compare_dataclasses(
                     dst.parent,
-                    _path_join(path, key),
+                    _path_join(op.path, op.key),
                     src,
                     dst,
                     frozen,

sdk/python/packages/flet/tests/test_object_diff_frozen.py

@@ -861,3 +861,73 @@ def test_component_list_diff():
     assert c1.parent == comp
     assert btn1.parent == c1
     assert txt1.parent == comp
+
+
+def test_list_insertions_no_keys():
+    col_1 = ft.Column(
+        [
+            ft.Text("Line 2", key=2),
+            ft.Text("Line 4", key=4),
+            ft.Text("Line 6", key=6),
+            ft.Text("Line 8", key=8),
+        ]
+    )
+    col_1._frozen = True
+    col_2 = ft.Column(
+        [
+            ft.Text("Line 1", key=1),
+            ft.Text("Line 2 (updated)", key=2),
+            ft.Text("Line 3", key=3),
+            ft.Text("Line 4 (updated)", key=4),
+            ft.Text("Line 5", key=5),
+            ft.Text("Line 6 (updated)", key=6),
+            ft.Text("Line 7", key=7),
+        ]
+    )
+    patch, msg, added_controls, removed_controls = make_diff(col_2, col_1)
+
+    assert cmp_ops(
+        patch,
+        [
+            {
+                "op": "add",
+                "path": ["controls", 0],
+                "value": ft.Text(value="Line 1", key=1),
+            },
+            {
+                "op": "replace",
+                "path": ["controls", 1, "value"],
+                "value": "Line 2 (updated)",
+            },
+            {
+                "op": "add",
+                "path": ["controls", 2],
+                "value": ft.Text(value="Line 3", key=3),
+            },
+            {
+                "op": "remove",
+                "path": ["controls", 5],
+                "value": ft.Text(value="Line 8", key=8),
+            },
+            {
+                "op": "replace",
+                "path": ["controls", 3, "value"],
+                "value": "Line 4 (updated)",
+            },
+            {
+                "op": "add",
+                "path": ["controls", 4],
+                "value": ft.Text(value="Line 5", key=5),
+            },
+            {
+                "op": "replace",
+                "path": ["controls", 5, "value"],
+                "value": "Line 6 (updated)",
+            },
+            {
+                "op": "add",
+                "path": ["controls", 6],
+                "value": ft.Text(value="Line 7", key=7),
+            },
+        ],
+    )

sdk/python/packages/flet/tests/test_object_diff_in_place.py

@@ -1,6 +1,8 @@
 from dataclasses import field
 from typing import Any, Optional
 
+from pytest import raises
+
 import flet as ft
 from flet.components.component import Component
 from flet.controls.base_control import control
@@ -39,8 +41,7 @@ class SuperButton(Button):
     prop_2: Optional[str] = None
 
     def init(self):
-        print("SuperButton.init()")
-        assert not self.page
+        pass
 
     def build(self):
         print("SuperButton.build()")
@@ -213,7 +214,8 @@ def test_simple_page():
         SuperButton("Another Button"),
     ]
     del page.fonts["font2"]
-    assert page.controls[0].controls[0].page is None
+    with raises(RuntimeError):
+        assert page.controls[0].controls[0].page is None
 
     page._user_services._services[0].prop_2 = [2, 6]
 
@@ -291,7 +293,7 @@ def test_simple_page():
             {
                 "op": "add",
                 "path": ["views", 0, "controls", 0, "controls", 0],
-                "value": SuperButton("Bar"),
+                "value_type": SuperButton,
             },
             {
                 "op": "replace",
@@ -554,3 +556,53 @@ def test_overriding_controls_with_component():
     page.theme_mode = ft.ThemeMode.DARK
     patch, _, added_controls, removed_controls = make_diff(page, show_details=True)
     print(patch)
+
+
+def test_list_insertions():
+    col = ft.Column(
+        [
+            ft.Text("Line 2"),
+            ft.Text("Line 4"),
+            ft.Text("Line 6"),
+            ft.Text("Line 8"),
+        ]
+    )
+    _, patch, _, _, _ = make_msg(col, {})
+
+    # 1st update
+    col.controls[0] = ft.Text("Line 2 (updated)")
+    col.controls[1] = ft.Text("Line 4 (updated)")
+    col.controls[2] = ft.Text("Line 6 (updated)")
+
+    patch, _, _, _ = make_diff(col)
+    assert cmp_ops(
+        patch,
+        [
+            {"op": "replace", "path": ["controls", 0], "value_type": Text},
+            {"op": "replace", "path": ["controls", 1], "value_type": Text},
+            {"op": "replace", "path": ["controls", 2], "value_type": Text},
+        ],
+    )
+
+    # 2nd update
+    col.controls.insert(0, ft.Text("Line 1"))
+    col.controls.insert(2, ft.Text("Line 3"))
+    col.controls.insert(4, ft.Text("Line 5"))
+    col.controls.insert(6, ft.Text("Line 7"))
+    col.controls[3].value = "Line 4 (updated again)"
+
+    patch, _, _, _ = make_diff(col)
+    assert cmp_ops(
+        patch,
+        [
+            {"op": "add", "path": ["controls", 0], "value": ft.Text("Line 1")},
+            {"op": "add", "path": ["controls", 2], "value": ft.Text("Line 3")},
+            {
+                "op": "replace",
+                "path": ["controls", 3, "value"],
+                "value": "Line 4 (updated again)",
+            },
+            {"op": "add", "path": ["controls", 4], "value": ft.Text("Line 5")},
+            {"op": "add", "path": ["controls", 6], "value": ft.Text("Line 7")},
+        ],
+    )