vue element自定义表单验证请求后端接口验证

<el-form-item label="账户" prop="userid">
  <el-input v-model="addform.userid"></el-input>
</el-form-item>

import { checkuseridrepeat } from '@/api/user'

data: () => {
  var validateuserid = (rule, value, callback) => {
   if (value === '') {
    callback(new error('必填'))
   } else {
     checkuseridrepeat().then(response => {
      if ( response.code === '1') {
         callback(new error('已经存在，不能重复'))
        }
     })
    }
  }
  return {
    addrules: { // 新增表单校验
     userid: [
      { required: true, validator: validateuserid, trigger: 'blur' }
     ],    
    },
   }
 },