Table: fix expanded rows collapsing when data change (#9462)

packages/table/src/table-body.js

@@ -116,7 +116,7 @@ export default {
                   !this.fixed && this.layout.scrollY && this.layout.gutterWidth ? <td class="gutter" /> : ''
                 }
               </tr>,
-              this.store.states.expandRows.indexOf(row) > -1
+              this.store.isRowExpanded(row)
                 ? (<tr>
                   <td colspan={ this.columns.length } class="el-table__expanded-cell">
                     { this.table.renderExpanded ? this.table.renderExpanded(h, { row, $index, store: this.store }) : ''}

packages/table/src/table-store.js

@@ -405,6 +405,15 @@ TableStore.prototype.toggleRowExpansion = function(row, expanded) {
   }
 };
 
+TableStore.prototype.isRowExpanded = function(row) {
+  const { expandRows = [], rowKey } = this.states;
+  if (rowKey) {
+    const expandMap = getKeysMap(expandRows, rowKey);
+    return !!expandMap[getRowIdentity(row, rowKey)];
+  }
+  return expandRows.indexOf(row) !== -1;
+};
+
 TableStore.prototype.cleanSelection = function() {
   const selection = this.states.selection || [];
   const data = this.states.data;