From d55ff00a303ac908c29a238089c6c0103f7c0411 Mon Sep 17 00:00:00 2001
From: bnymncoskuner <bnymncoskuner@gmail.com>
Date: Tue, 15 Sep 2020 17:05:49 +0300
Subject: [PATCH 1/2] feat: add handleUpdate to tree adapter

---
 .../tree/src/lib/utils/nz-tree-adapter.ts           | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/npm/ng-packs/packages/components/tree/src/lib/utils/nz-tree-adapter.ts b/npm/ng-packs/packages/components/tree/src/lib/utils/nz-tree-adapter.ts
index 6c66315e69..ebabd201b0 100644
--- a/npm/ng-packs/packages/components/tree/src/lib/utils/nz-tree-adapter.ts
+++ b/npm/ng-packs/packages/components/tree/src/lib/utils/nz-tree-adapter.ts
@@ -48,7 +48,18 @@ export class TreeAdapter<T extends BaseNode = BaseNode> {
   }
 
   handleRemove({ key }: TreeNode<T>) {
-    this.tree = createTreeFromList(this.list.filter(item => item.id !== key));
+    this.updateTreeFromList(this.list.filter(item => item.id !== key));
+  }
+
+  handleUpdate({ key, children }: { key: string; children: T[] }) {
+    // remove current children and update tree
+    this.updateTreeFromList(this.list.filter(item => item.parentId !== key));
+    // add new children and update tree
+    this.updateTreeFromList(this.list.concat(children));
+  }
+
+  updateTreeFromList(list: T[]) {
+    this.tree = createTreeFromList(list);
     this.list = createListFromTree(this.tree);
   }
 }

From 494e2dba9132bf901527fcc859c2d7005a7ccbb6 Mon Sep 17 00:00:00 2001
From: bnymncoskuner <bnymncoskuner@gmail.com>
Date: Wed, 16 Sep 2020 09:22:59 +0300
Subject: [PATCH 2/2] chore: add explanation to handleUpdate

---
 .../tree/src/lib/utils/nz-tree-adapter.ts         | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/npm/ng-packs/packages/components/tree/src/lib/utils/nz-tree-adapter.ts b/npm/ng-packs/packages/components/tree/src/lib/utils/nz-tree-adapter.ts
index ebabd201b0..d5d32f0146 100644
--- a/npm/ng-packs/packages/components/tree/src/lib/utils/nz-tree-adapter.ts
+++ b/npm/ng-packs/packages/components/tree/src/lib/utils/nz-tree-adapter.ts
@@ -52,15 +52,22 @@ export class TreeAdapter<T extends BaseNode = BaseNode> {
   }
 
   handleUpdate({ key, children }: { key: string; children: T[] }) {
-    // remove current children and update tree
-    this.updateTreeFromList(this.list.filter(item => item.parentId !== key));
-    // add new children and update tree
-    this.updateTreeFromList(this.list.concat(children));
+    /**
+     * When we need to update a node with new children, first we need to remove any descendant nodes.
+     * If we remove immediate children and create a new tree, any other descendant nodes will be removed
+     * and we won't need to recursively remove sub children.
+     * Then, you simply add back the new children and create a new tree.
+     */
+    const listWithDescendantNodesRemoved = this.updateTreeFromList(
+      this.list.filter(item => item.parentId !== key),
+    );
+    this.updateTreeFromList(listWithDescendantNodesRemoved.concat(children));
   }
 
   updateTreeFromList(list: T[]) {
     this.tree = createTreeFromList(list);
     this.list = createListFromTree(this.tree);
+    return this.list;
   }
 }