基于非空字符串的Joi条件验证

Question

我正在尝试使用joi进行条件验证。代码在下面

const Joi = require('joi');

const joiSampleSchema = Joi.object().keys({
     data: Joi.object().keys({
          param1: Joi.string().required(),
          param2: Joi.string().required(),
          alphabets: Joi.array().items({
               name: Joi.string().required(),
               numbers: Joi.array().items({
                    first: Joi.optional(),
                    second: Joi.optional(),
                    name: Joi.string().when(
                         'first', {
                              is: '',
                              then: Joi.optional(),
                              otherwise: Joi.string().required()
                         }),
                    name1: Joi.string().when(
                         'first', {
                              is: '',
                              then: Joi.optional(),
                              otherwise: Joi.string().required()
                         }),
                    class: Joi.string().when(
                         'second', {
                              is: '',
                              then: Joi.optional(),
                              otherwise: Joi.string().required()
                         }),
                    class1: Joi.string().when(
                         'second', {
                              is: '',
                              then: Joi.optional(),
                              otherwise: Joi.string().required()
                         }),
               })

          })
     })
});

const options = {
     allowUnknown: true
     , stripUnknown: false
}

const result = Joi.validate(joisamplejson, joiSampleSchema, options);

if (result.error && result.error.details) {
     result.error.details.forEach(function (error) {
          console.log('Errored parameter: '+error.path.join("."));
     });
};

下面是我要验证的json

{
     "data": {
       "param1": "param1value",
       "param2": "param2value",
       "alphabets": [
         {
           "name": "a",
           "numbers": [
             {
               "first": "",
               "second": "dafe",
               "name": "",
               "name1": "peter1",
               "class": "kekk",
               "class1":"kekk1"
             },
             {
               "first": "asd",
               "second": "dafe",
               "name": "james",
               "name1": "james1",
               "class": "jejj",
               "class1":"jejj1"
             }
           ]
         }
       ]
     }
   }

我要针对这种情况进行验证：
在“数字”数组中，当参数“第一”为空字符串或未定义时，在验证时应忽略参数“名称”和“名称1”。如果参数“ first”的值是一个非空字符串，则参数“名称”和“ name1”的值应是非空字符串。同样的情况适用于参数“ second”，“ class”和“ class1”。

但是上面的代码无法实现这一点。请帮忙。

预先感谢