如何在v-autocomplete中搜索不是作为项的值

<template>
  <v-autocomplete
    v-model="selectedItem"
    :items="items"
    :filter="customFilter"
    label="Search"
  ></v-autocomplete>
</template>

<script>
export default {
  data() {
    return {
      selectedItem: null,
      items: ['Apple', 'Banana', 'Orange', 'Mango']
    };
  },
  methods: {
    customFilter(item, queryText, itemText) {
      // 判断项的值是否包含查询文本
      return itemText.toLowerCase().indexOf(queryText.toLowerCase()) > -1;
    }
  }
};
</script>