Question

基本上，我的用例是创建注册表格并将其链接到区块链。到目前为止，我的合同已经在Remix中工作（版本0.4.25编译），但是，当我去尝试使用reactJS将数据提交到区块链时，会出现错误

节点错误：{“消息”：“无法从null读取属性” ...“

有人可以帮我吗？

App.js：

onsaveInfo = async (event) =>{
    /*var data={
      fname:this.state.fname,
      lname:this.state.lname,
      phone:this.state.phno
    }*/
    console.log("final data-----",this.state._fname,this.state._lname,this.state._phno);
    localStorage.setItem('data',this.state._fname,this.state._lname,this.state._phno);
    console.log("1------------",getWeb3);
    // getWeb3.then(results=>{
    //   let web3 = results.payload.web3Instance;
    //   var callingAddress= web3.currentProvider['publicConfigStore'].getState().selectedAddress;
    //   console.log("2-----------------",callingAddress);
    // })
    const web3 = new Web3(new Web3.providers.HttpProvider('http://localhost:8545'));
    console.log("current provider ------",web3.eth.givenProvider.selectedAddress);
    // web3.eth.getAccounts(console.log);
    //alert("qwertyuiop");
    const contractInstance = new web3.eth.Contract(this.state.contractAbi,this.state.contractAddress);
    console.log(contractInstance);
    await contractInstance.methods.createRandomUser(this.state._fname,this.state._lname,this.state._phno).call(function(error,result){
      if(!error){
        console.log("result========",result);
      }
    });



  }
  render() {
    if (!this.state.web3) {
      return <div>Loading Web3, accounts, and contract...</div>;
    }
    return (
      <div className="App">

       <div className="col-md-12">
         <div className="card">
           <label>First Name : </label>
         <input type="text" placeholder="firstName" onChange={(event)=>this.setState({_fname:event.target.value})}/>
         <br></br>
         <label>Last Name : </label>
         <input type="text" placeholder="lastName" onChange={(event)=>this.setState({_lname:event.target.value})}/>
         <br></br>
         </div>
         <label>Ph No : </label>
         <input type="text" placeholder="phNo" onChange={(event)=>this.setState({_phno:event.target.value})}/>
         <br></br>
         <label>Role : </label>
         <select>
           <option >Select</option>
           <option value="Driver1" onClick={event=>this.setState({roleName:event.target.value})}>Driver1</option>
           <option value="Driver2" onClick={event=>this.setState({roleName:event.target.value})}>Driver2</option>
           <option value="Driver3" onClick={event=>this.setState({roleName:event.target.value})}>Driver3</option>
         </select>
         <br></br>
       </div>
       <div>
         <input type="button" onClick={event=>this.onsaveInfo(event)} value='Save Info'/>
       </div>
      </div>
    );

书面合同：

pragma solidity ^0.4.25;

contract ambFactory {
    struct User {
        string _fname;
        string _lname;
        uint _phno;
    }

    uint phDigits = 10;
    uint phModulus = 10 ** phDigits;

    User[] public users;

    function _setProfile(string _fname, string _lname, uint _phno) private {
        users.push(User(_fname, _lname, _phno));
    }

    /*function _genRandomUser(string _str) private view returns (uint) {
        uint rand = uint(keccak256(abi.encodePacked(_str)));
        return rand % phModulus;
    }*/

    function createRandomUser(string _fname, string _lname, uint _phno) public {
        //uint randNo = _genRandomUser(_fname);
        _setProfile(_fname, _lname, _phno);
    }
}

我希望信息会发送到我设置的本地区块链上，并且交易会反映在MetaMask（我正在使用的提供程序）中，但是，不会出现这样的交易确认窗口，并且会得到错误。 / p>

如何解决实体性和reactjs end2end交互中的“节点错误：无法从null的属性'读取'”错误

0 个答案: