当用户点击按钮时,我正试图在彼此之后运行3种方法
脚步:
1:将文件推送到IPFS,获取链接并将其分配给状态变量
2:将该链接(从该var)添加到区块链智能合约
3:向firebase数据库添加条目
问题是,当我尝试将IPFS链接传递给我的智能合约时,IPFS链接为空,但是在方法运行后,我可以看到链接打印到控制台。所以我猜测它没有及时设置下一个查看变量的方法。
IPFS方法:
pushToIPFS = async(e) => {
// e.preventDefault()
await ipfs.add(this.state.buffer, (err, ipfsHash) => {
console.log(err, ipfsHash)
//this.setState({IPFSlink : ipfsHash[0].hash})
console.log(ipfsHash[0].hash)
return ipfsHash[0].hash
})
}
区块链方法:
addToBlockchain = async(e) => {
//create a new key for our student
var key = this.state.StudentNumber + this.state.account[0]
key = parseInt(hash(key), 10)
this.setState({idForBlockchain: key})
console.log(key)
//get todays date
let newDate = new Date()
newDate = newDate.getTime()
var _ipfsLink = this.state.IPFSlink
var _account = this.state.account[0]
console.log(_ipfsLink)
console.log(this.state.IPFSlink)
await storehash.methods.sendDocument(_ipfsLink, newDate,
}
Firebase方法:
createStudent = async(e) => {
//get student details from state variables & current user uid
var _uid = this.state.uid
var _studentName = this.state.StudentName
var _studentNumber = this.state.StudentNumber
var _courseCode = this.state.CourseCode
var _courseName = this.state.CourseName
var _idForBlockchain = this.state.idForBlockchain
// database.ref.students.uid.studentNumber
const db = firebase.database()
db.ref().child("students").child(_uid).child(_studentNumber).set(
{ studentName: _studentName,
courseCode: _courseCode,
courseName: _courseName,
blockchainKey: _idForBlockchain
}
);
alert("Student added")
}
单击按钮时触发的方法:
AddMyStuff = async (e) => {
e.preventDefault()
await this.pushToIPFS()
await this.addToBlockchain()
await this.createStudent()
}
这是返回的错误,所以我假设await和setState导致问题并且我需要的变量没有被设置。
未处理的拒绝(错误):无效的字符串值(arg =“_ ipfsLocation”,coderType =“string”,value = null,version = 4.0.27)
有谁知道如何解决这个问题?
你可以将pushToIPFS转换为一个promise而不是一个回调,并在触发回调时解决它。
pushToIPFS = (e) => {
return new Promise((resolve, reject) => {
ipfs.add(this.state.buffer, (err, ipfsHash) => {
resolve(ipfsHash[0].hash);
})
});
}
而且因为它的承诺你可以使用async/await
。
AddMyStuff = async (e) => {
e.preventDefault()
const ipfsHash = await this.pushToIPFS();
//you have your ipfsHash defined, you can pass it to your other methods
}