如图，点击新增的时候自动获取当前的时间来作为创建时间

时间组件：

      <el-form-item label="创建时间" prop="createTime">
        <el-date-picker
          v-model="createTime"
          type="datetime"
          value-format="x"
          placeholder="选择创建时间"
        />
      </el-form-item>

formData：

const formData = ref({
  id: undefined,
  courseType: undefined,
  subject: undefined,
  fileType: undefined,
  appendixName: undefined,
  creator:  userStore.user.id,
  createTime: undefined,
})

const createTime = ref('')

打开弹窗时给创建时间赋值：

/** 打开弹窗 */
const open = async (type: string, id?: number) => {
  createTime.value = dateFormat()
  dialogVisible.value = true
  dialogTitle.value = t('action.' + type)
  formType.value = type
  resetForm()
  userList.value = await UserApi.getSimpleUserList()
  // 修改时，设置数据
  if (id) {
    formLoading.value = true
    try {
      formData.value = await ResearchingManageApi.getResearchingManage(id)
     formData.value.createTime = createTime.value

    } finally {
      formLoading.value = false
    }
  }
  // 获得登录人名称
  userList.value = await UserApi.getSimpleUserList()
  userList.value.forEach((item) => {
    if (item.id === userStore.user.id) {
      creator.value = item.nickname
    }
  })
}

获取时间方法：

const dateFormat = ()=>{
  let date = new Date();
      let y = date.getFullYear();
      let MM = date.getMonth() + 1<10? ('0' + (date.getMonth() + 1)) : date.getMonth() + 1;
      let d = date.getDate()< 10 ? ('0' + date.getDate()) :  date.getDate()
      let h = date.getHours() < 10 ? ('0' +date.getHours()) : date.getHours();
      const m = date.getMinutes()< 10 ? ('0' + date.getMinutes()) : date.getMinutes();
      let s = date.getSeconds() < 10 ? ('0' +date.getSeconds()) : date.getSeconds();
      console.log( y + '-' + MM + '-' + d + ' ' + h + ':' + m  + ':' +s)
      return  y + '-' + MM + '-' + d + ' ' + h + ':' + m  + ':' +s
}

为了怕大家找不到代码应该放在那里，我就在下面放上完整代码，大家自行查找，谢谢大家。

<template>
  <Dialog :title="dialogTitle" v-model="dialogVisible">
    <el-form
      ref="formRef"
      :model="formData"
      :rules="formRules"
      label-width="100px"
      v-loading="formLoading"
    >
    <div style="padding: 8px 0;background: #f8fbff">
       
        <el-row :gutter="24">
      <el-form-item label="课程类型" prop="courseType">
        <el-select v-model="formData.courseType" placeholder="请选择课程类型">
          <el-option
            v-for="dict in getStrDictOptions(DICT_TYPE.COURSE_TYPE)"
            :key="dict.value"
            :label="dict.label"
            :value="dict.value"
          />
        </el-select>
      </el-form-item>
      <el-form-item label="科目" prop="subject">
        <el-select v-model="formData.subject" placeholder="请选择科目">
          <el-option
            v-for="dict in getStrDictOptions(DICT_TYPE.SUBJECT)"
            :key="dict.value"
            :label="dict.label"
            :value="dict.value"
          />
        </el-select>
      </el-form-item>
      <el-form-item label="文件类型" prop="fileType">
        <el-select v-model="formData.fileType" placeholder="请选择文件类型">
          <el-option
            v-for="dict in getStrDictOptions(DICT_TYPE.FILE_TYPE)"
            :key="dict.value"
            :label="dict.label"
            :value="dict.value"
          />
        </el-select>
      </el-form-item>
      <el-form-item label="附件名称" prop="appendixName">
        <el-input v-model="formData.appendixName" placeholder="请输入附件名称" />
      </el-form-item>
      <el-form-item label="创建人" prop="creator">
            <el-select v-model="formData.creator" placeholder="请选择创建人">
              <el-option
                v-for="dict in userList"
                :key="dict.id"
                :label="dict.nickname"
                :value="dict.id"
              />
            </el-select>
          </el-form-item>
      <el-form-item label="创建时间" prop="createTime">
        <el-date-picker
          v-model="createTime"
          type="datetime"
          value-format="x"
          placeholder="选择创建时间"
        />
      </el-form-item>
    </el-row>
  </div>
    </el-form>
    <template #footer>
      <el-button @click="submitForm" type="primary" :disabled="formLoading">确 定</el-button>
      <el-button @click="dialogVisible = false">取 消</el-button>
    </template>
  </Dialog>
</template>
<script setup lang="ts">
import { getStrDictOptions, DICT_TYPE } from '@/utils/dict'
import { ResearchingManageApi, ResearchingManageVO } from '@/api/teach/researchingmanage'
import { useUserStore } from '@/store/modules/user'
import * as UserApi from '@/api/system/user'
const userStore = useUserStore()
/** 教研管理 表单 */
defineOptions({ name: 'ResearchingManageForm' })
const userList = ref<UserApi.UserVO[]>([]) // 用户列表
const { t } = useI18n() // 国际化
const message = useMessage() // 消息弹窗

const dialogVisible = ref(false) // 弹窗的是否展示
const dialogTitle = ref('') // 弹窗的标题
const formLoading = ref(false) // 表单的加载中：1）修改时的数据加载；2）提交的按钮禁用
const formType = ref('') // 表单的类型：create - 新增；update - 修改
const formData = ref({
  id: undefined,
  courseType: undefined,
  subject: undefined,
  fileType: undefined,
  appendixName: undefined,
  creator:  userStore.user.id,
  createTime: undefined,
})
const formRules = reactive({
})
const createTime = ref('')
const formRef = ref() // 表单 Ref
const creator = ref('')
/** 打开弹窗 */
const open = async (type: string, id?: number) => {
  createTime.value = dateFormat()
  dialogVisible.value = true
  dialogTitle.value = t('action.' + type)
  formType.value = type
  resetForm()
  userList.value = await UserApi.getSimpleUserList()
  // 修改时，设置数据
  if (id) {
    formLoading.value = true
    try {
      formData.value = await ResearchingManageApi.getResearchingManage(id)
     formData.value.createTime = createTime.value

    } finally {
      formLoading.value = false
    }
  }
  // 获得登录人名称
  userList.value = await UserApi.getSimpleUserList()
  userList.value.forEach((item) => {
    if (item.id === userStore.user.id) {
      creator.value = item.nickname
    }
  })
}
defineExpose({ open }) // 提供 open 方法，用于打开弹窗
const dateFormat = ()=>{
  let date = new Date();
      let y = date.getFullYear();
      let MM = date.getMonth() + 1<10? ('0' + (date.getMonth() + 1)) : date.getMonth() + 1;
      let d = date.getDate()< 10 ? ('0' + date.getDate()) :  date.getDate()
      let h = date.getHours() < 10 ? ('0' +date.getHours()) : date.getHours();
      const m = date.getMinutes()< 10 ? ('0' + date.getMinutes()) : date.getMinutes();
      let s = date.getSeconds() < 10 ? ('0' +date.getSeconds()) : date.getSeconds();
      console.log( y + '-' + MM + '-' + d + ' ' + h + ':' + m  + ':' +s)
      return  y + '-' + MM + '-' + d + ' ' + h + ':' + m  + ':' +s
}
/** 提交表单 */
const emit = defineEmits(['success']) // 定义 success 事件，用于操作成功后的回调
const submitForm = async () => {
  // 校验表单
  await formRef.value.validate()
  // 提交请求
  formLoading.value = true
  try {
    const data = formData.value as unknown as ResearchingManageVO
    if (formType.value === 'create') {
      await ResearchingManageApi.createResearchingManage(data)
      message.success(t('common.createSuccess'))
    } else {
      await ResearchingManageApi.updateResearchingManage(data)
      message.success(t('common.updateSuccess'))
    }
    dialogVisible.value = false
    // 发送操作成功的事件
    emit('success')
  } finally {
    formLoading.value = false
  }
}

/** 重置表单 */
const resetForm = () => {
  formData.value = {
    id: undefined,
    courseType: undefined,
    subject: undefined,
    fileType: undefined,
    appendixName: undefined,
    creator: userStore.user.id,
    createTime: undefined,
  }
  formRef.value?.resetFields()
}
</script>
<style scoped lang="scss">
.el-form-item{
  width: 47%;
}
:deep(.el-form-item__label){
  width: 130px !important;
}
.bold{
  width: 20px;
  height:20px;
  border-radius: 50%;
  background:#85afd5;
  text-align: center;
  margin-top:5px;
  margin-left:-10px;
  color:#fff
}
.btitle{
  line-height:30px;
  margin-left:10px;
  color:#84b0d5
}
.tip{
  border:1px solid #84b0d5;
  border-radius:0 20px 20px 0;
  width:140px;
  height:30px;
  display:flex;
  margin-left:30px;
  margin-bottom:20px
}
:deep(.el-form-item__content){
  display: block;
}
:deep(.el-date-editor.el-input, .el-date-editor.el-input__wrapper){
  width: -webkit-fill-available;
}
.textarea{
  width: 94%;
}
</style>