第一次使用vue搭建Dapp项目，意图是提交表单，通过智能合约中方法将数据存储到区块链中，

其中 表单数据结构为：

struct  CarInfo{
        string  name;
        string  description;
        uint  reward;
        uint  waitTime;
        uint  longitude;
        uint  latitude;
    }

智能合约对应方法为：

function addCarInfo(string memory _name,string memory _description,uint _reward,  uint _waitTime,uint _longitude,uint _latitude) public {
        //在列表中新增数据
        //这个地方应该新增
        CarInfo memory carInfo = CarInfo(_name,_description,_reward,_waitTime,_longitude,_latitude);  // 按定义的顺序依次指定值
        CarInfos[msg.sender].push(carInfo);
        emit NewCarInfo();
    }

vue的相关代码为：

<template>
  <div style="text-align: left">
    <el-button class="add-button" type="success" @click="dialogFormVisible = true">新建任务</el-button>
    <el-dialog
      title="新建任务"
      :visible.sync="dialogFormVisible"
      @close="clear">
      <el-form v-model="form" style="text-align: left" ref="dataForm">
        <el-form-item label="任务名" :label-width="formLabelWidth" prop="name">
          <el-input v-model="form.name" autocomplete="off" placeholder=""></el-input>
        </el-form-item>
        <el-form-item label="任务描述" :label-width="formLabelWidth" prop="description">
          <el-input v-model="form.description" autocomplete="off"></el-input>
        </el-form-item>
        <el-form-item label="任务奖励" :label-width="formLabelWidth" prop="reward">
          <el-input-number v-model="form.reward" :min="1" :max="50" ></el-input-number>  wei
        </el-form-item>
        <el-form-item label="可等时间" :label-width="formLabelWidth" prop="waitTime">
          <el-input-number v-model="form.reward" :min="1" :max="360" ></el-input-number>  分钟
        </el-form-item>
        <el-form-item label="经度" :label-width="formLabelWidth" prop="longitude">
          <el-input v-model="form.longitude" autocomplete="off" placeholder=""></el-input>
        </el-form-item>
        <el-form-item label="纬度" :label-width="formLabelWidth" prop="latitude">
          <el-input v-model="form.latitude" autocomplete="off"></el-input>
        </el-form-item>
      </el-form>
      <div slot="footer" class="dialog-footer">
        <el-button @click="dialogFormVisible = false">取 消</el-button>
        <el-button type="primary" @click="onSubmit">确 定</el-button>
      </div>
    </el-dialog>
  </div>
</template>

<script>
  import Web3 from "web3";
  import contract from "truffle-contract";
  let CarContract = require("../../build/contracts/CarContract.json");

  export default {
    name: 'VehicleBC',
    data () {
      return {
        dialogFormVisible: false,
        form: {
          name: '',
          description: '',
          reward: '',
          waitTime: '',
          longitude: '',
          latitude: '',
        },
        formLabelWidth: '120px',
      }
    },
    methods: {
      clear () {
        this.form = {
          name: '',
          description: '',
          reward: '',
          waitTime: '',
          longitude: '',
          latitude: '',
        }
      },
      onSubmit () {
        this.carTask.addCarInfo(this.form.name,this.form.description,this.form.reward,this.form.waitTime,this.form.longitude,this.form.latitude).then(function (result) {
            alert(result);
        })
      },

      async initWeb3Account() {
        if (window.ethereum) {
          this.provider = window.ethereum;
          try {
            await window.ethereum.enable();
          } catch (error) {
              console.log("User denied account access");
          }
        } else if (window.web3) {
          this.provider = window.web3.currentProvider;
        } else {
          this.provider = new Web3.providers.HttpProvider("http://127.0.0.1:7545");
        }
        this.web3 = new Web3(this.provider);

        this.web3.eth.getAccounts().then(accs  => {
          this.account = accs[0]
        })
      },
      async initContract() {
        const crowdContract = contract(CarContract)
        crowdContract.setProvider(this.provider)
        this.carTask = await crowdContract.deployed()
      },
      async getCarTaskInfo() {
        this.carTask.getCarInfoLen(this.account).then(function (len) {
          console.log(len + " 条笔记");
        })
      },
    },
    mounted() {
    },
    // 当前Vue组件被创建时回调的hook 函数
    async created() {
      //  初始化 web3及账号
      await this.initWeb3Account()
      //  初始化合约实例
      await this.initContract()
      //  获取合约的状态信息
      await this.getCarTaskInfo()
    },
  }
</script>

<style scoped>
  .add-button {
    margin: 18px 0 0 10px;
  }
</style>

项目中新建任务弹出表单，填写完毕提交出现 The send transactions "from" field must be defined!错误。 整个项目是模仿着tiny熊的如何使用Vue.js 开发以太坊DApp来学习的。请问有大神可以指点一下吗？