Fetch the right column value, even if the data-field is a multi level (#4897)

referenz

Co-authored-by: Dennis Hernández <dennishernandezvargas@gmail.com>

src/extensions/multiple-sort/bootstrap-table-multiple-sort.js

@@ -608,8 +608,8 @@ BootstrapTable.prototype.onMultipleSort = function () {
       }
 
       const order = that.options.sortPriority[i].sortOrder === 'desc' ? -1 : 1
-      let aa = a[fieldName]
-      let bb = b[fieldName]
+      let aa = Utils.getItemField(a, fieldName)
+      let bb = Utils.getItemField(b, fieldName)
       const value1 = $.fn.bootstrapTable.utils.calculateObjectValue(that.header, sorterName, [aa, bb])
       const value2 = $.fn.bootstrapTable.utils.calculateObjectValue(that.header, sorterName, [bb, aa])