把项目中energyType数组转变为字符串

Question

项目中energyType数组后端无法接收，要转变成字符串传给后端，组件图片如下

组件代码如下
操作台打印数据如下

<template>
  <div class="focus_tab_pane">
    <div class="approval">
      <div class="title flex justify-between align-center">
        <el-button
          type="text"
          size="medium"
          style="color:#E6A23C"
          @click="download"
        >
          样本信息下载
        </el-button>
      </div>
    </div>
    <!-- 样本信息下载 -->
    <el-dialog
      :visible="isVisible"
      width="400px"
      title="类型选择"
      :before-close="closeDialog"
      :close-on-click-modal="false"
    >
      <el-form
        ref="searchForm"
        :model="searchForm"
        :rules="searchFormRules"
        label-width="100px"
      >
        <el-form-item label="年度" prop="year">
          <el-date-picker
            v-model="searchForm.year"
            type="year"
            value-format="yyyy"
            :clearable="false"
            placeholder="请选择"
          />
        </el-form-item>
        <el-form-item label="时期" prop="period">
          <el-select v-model="searchForm.period" placeholder="请选择">
            <el-option label="上半年" value="0" />
            <el-option label="下半年" value="1" />
          </el-select>
        </el-form-item>
        <el-form-item label="营运类型" prop="energyType">
          <el-select v-model="searchForm.energyType" multiple placeholder="请选择">
            <el-option label="公路客运" value="1" />
            <el-option label="公路货运" value="2" />
            <el-option label="出租客运" value="3" />
            <el-option label="公交公司" value="4" />
            <el-option label="水路客运" value="5" />
            <el-option label="水路货运" value="6" />
            <el-option label="港口企业" value="7" />
          </el-select>
        </el-form-item>
      </el-form>
      <div slot="footer" class="dialog-footer">
        <el-button size="medium" @click="closeDialog">取消</el-button>
        <el-button
          size="medium"
          type="primary"
          :loading="apiLoading"
          @click="validateForm"
        >
          确认
        </el-button>
      </div>
    </el-dialog>
  </div>
</template>

<script>
import { noSay } from '@/api/focus'
import { convertRes2Blob, getYear } from '@/api/public'

export default {
  name: 'ListTabPane',
  props: {
    status: {
      type: Number,
      required: true
    }
  },

  data() {
    return {
      loading: false,
      showMore: false,
      natureTypeList: [],
      list: [],
      matchingNumberList: [],
      searchForm: {
        year: null,
        period: null,
        energyType: []
      },
      searchFormRules: {
        year: [{ required: true, trigger: 'change', message: '请选择年度' }],
        period: [{ required: true, trigger: 'change', message: '请选择时期' }],
        energyType: [{ required: true, trigger: 'change', message: '请选择营运类型' }]
      },
      isVisible: false,
      apiLoading: false,
      period: null,
      year: null,
      energyType: []
    }
  },
  created() {
    const natureTypeList = []
    this.matchingList.forEach(element => {
      this.$store.getters.companys.natureTypeList.forEach(item => {
        if (element.type === item.natureTypeCode) {
          natureTypeList.push(element)
        }
      })
    })
    this.natureTypeList = natureTypeList
    this.getTypeList()
    this.handleYear()
  },
  methods: {
    async handleYear() {
      const res = await getYear()
      console.log(res)
      this.period = res.period
      this.year = res.year
      this.energyType = res.energyType
    },
    download() {
      this.isVisible = true
    },
    closeDialog() {
      this.isVisible = false
      this.apiLoading = false
      this.$refs['searchForm'].resetFields()
    },
    validateForm() {
      this.$refs['searchForm'].validate(valid => {
        valid && this.submitForm()
      })
    },
    submitForm() {
      this.apiLoading = true
      noSay({ ...this.searchForm }).then(res => {
        convertRes2Blob(res, '样本信息')
        setTimeout(() => {
          this.apiLoading = false
          this.closeDialog()
        })
      })
    }
  }
}
</script>


// 样本信息下载
export function noSay(params) {
  return request({
    url: 'energy/excel/export',
    method: 'POST',
    responseType: 'blob',
    data: params
  })
}

// 年度查询
export function getYear() {
  return request({
    url: 'energy/enterpriseSampleInfo/time',
    method: 'GET'
  })
}

就是要把energyType从数组转变为字符串，用‘，’隔开，我之前写的如下

methods: {
    async handleYear() {
      const params = JSON.parse(JSON.stringify(this.form))
      params.energyType = params.energyType.join(',')
      const res = await getYear()
      console.log(res)
      this.period = res.period
      this.year = res.year
      this.energyType = res.energyType
    },
}

报错TypeError: Cannot read properties of undefined (reading 'join')

Answer 1

energyType 说明这个不是数组 。用不了join方法