a-select中placeholder设置无效的解决办法

placeholder设置无效代码

<a-form-model-item label="企业类型：" :labelCol="labelCol" :wrapperCol="wrapperCol" prop="type">
      <a-select v-model="form.type" placeholder='请选择企业类型'>
        <a-select-option :value="1">系统内</a-select-option>
        <a-select-option :value="2">系统外</a-select-option>
      </a-select>
    </a-form-model-item>
form: {
        type: '',
        },

image.png

解决方法：
将type置为undefined

form: {
        type: undefined,
        },

image.png