bug fix : expand all leaf nodes in root level

components/tree/DirectoryTree.tsx

@@ -5,7 +5,7 @@ import FolderOutlined from '@ant-design/icons/FolderOutlined';
 import classNames from 'classnames';
 import type RcTree from 'rc-tree';
 import type { BasicDataNode } from 'rc-tree';
-import type { DataNode, EventDataNode, Key } from 'rc-tree/lib/interface';
+import type { DataNode, EventDataNode, Key, KeyEntities } from 'rc-tree/lib/interface';
 import { conductExpandParent } from 'rc-tree/lib/util';
 import { convertDataToEntities, convertTreeToData } from 'rc-tree/lib/utils/treeUtil';
 
@@ -52,7 +52,7 @@ const DirectoryTree: React.ForwardRefRenderFunction<RcTree, DirectoryTreeProps>
   const cachedSelectedKeys = React.useRef<Key[]>();
 
   const getInitExpandedKeys = () => {
-    const { keyEntities } = convertDataToEntities(getTreeData(props));
+    const { keyEntities }: { keyEntities: KeyEntities } = convertDataToEntities(getTreeData(props));
 
     let initExpandedKeys: Key[];
 
@@ -65,7 +65,17 @@ const DirectoryTree: React.ForwardRefRenderFunction<RcTree, DirectoryTreeProps>
         keyEntities,
       );
     } else {
-      initExpandedKeys = (props.expandedKeys || defaultExpandedKeys)!;
+      initExpandedKeys = props.expandedKeys || defaultExpandedKeys || [];
+      // If not specified, expand all leaf nodes in the first level.
+      const firstLayerLeafs = Object.values(keyEntities)
+        .filter((item) => {
+          if (item.parent === undefined && item?.node.isLeaf === true) {
+            return true;
+          }
+          return false;
+        })
+        .map((item) => item.key);
+      initExpandedKeys = Array.from(new Set([...initExpandedKeys, ...firstLayerLeafs]));
     }
     return initExpandedKeys;
   };