ElementUi中el-cascader表单验证问题

   <el-form-item
          label="地区"
          prop="region"
          :rules="{
            required: true,
            message: '请选择',
            trigger: 'change',
          }"
        >
          <el-cascader
            v-model="form.region"
            style="width: 100%"
            :options="selectedOptions"
            @change="handleChange"
            :props="{ checkStrictly: true }"
            clearable
            placeholder="请选择"
          ></el-cascader>
        </el-form-item>

   // 所在地区值
    handleChange(value) {
      console.log(value);
      if (value.length === 0) {
        return
      } else {
        this.form.region = value
      }
    },