From 3f0714cebf290c5699ed372d5b629768d59b0700 Mon Sep 17 00:00:00 2001
From: 07akioni <07akioni2@gmail.com>
Date: Sat, 5 Jun 2021 21:30:39 +0800
Subject: [PATCH] fix(collapse): `default-expanded-names` not working

---
 CHANGELOG.en-US.md            |  4 ++++
 CHANGELOG.zh-CN.md            |  6 ++++++
 src/collapse/src/Collapse.tsx | 14 +++++++++-----
 3 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.en-US.md b/CHANGELOG.en-US.md
index 63fa95625..5e394b64a 100644
--- a/CHANGELOG.en-US.md
+++ b/CHANGELOG.en-US.md
@@ -1,5 +1,9 @@
 # CHANGELOG
 
+## Pending
+
+- Fix `n-collapse` `default-expanded-names` not working.
+
 ## 2.11.2
 
 ### Fixes
diff --git a/CHANGELOG.zh-CN.md b/CHANGELOG.zh-CN.md
index e8a45d6d1..f705261dd 100644
--- a/CHANGELOG.zh-CN.md
+++ b/CHANGELOG.zh-CN.md
@@ -1,5 +1,11 @@
 # CHANGELOG
 
+## Pending
+
+### Fixes
+
+- 修复 `n-collapse` `default-expanded-names` 不生效
+
 ## 2.11.2
 
 ### Fixes
diff --git a/src/collapse/src/Collapse.tsx b/src/collapse/src/Collapse.tsx
index 4e302d421..8e0dd407c 100644
--- a/src/collapse/src/Collapse.tsx
+++ b/src/collapse/src/Collapse.tsx
@@ -29,9 +29,12 @@ import {
 
 const collapseProps = {
   ...(useTheme.props as ThemeProps<CollapseTheme>),
-  defaultExpandesNames: [Array, String] as PropType<
-  string | number | Array<string | number> | null
-  >,
+  defaultExpandedNames: {
+    type: [Array, String] as PropType<
+    string | number | Array<string | number> | null
+    >,
+    default: null
+  },
   expandedNames: [Array, String] as PropType<
   string | number | Array<string | number> | null
   >,
@@ -98,8 +101,9 @@ export default defineComponent({
   props: collapseProps,
   setup (props, { slots }) {
     const { mergedClsPrefixRef } = useConfig(props)
-    const uncontrolledExpandedNamesRef =
-      ref<string | number | Array<string | number> | null>(null)
+    const uncontrolledExpandedNamesRef = ref<
+    string | number | Array<string | number> | null
+    >(props.defaultExpandedNames)
     const controlledExpandedNamesRef = computed(() => props.expandedNames)
     const mergedExpandedNamesRef = useMergedState(
       controlledExpandedNamesRef,