如果路径和文件在NodeJS中不存在，则创建路径和文件写就绪writeStream

yhived7q 于 2022-12-18 发布在 Node.js

关注(0)|答案(2)|浏览(171)

基于other questions（如下所示）和文档，我有以下代码，当它不存在时，应该创建一个新的目录和文件，或者当它存在时，应该替换它：

require('fs')

;(async ()=>{

//ref 1
fs.closeSync(fs.openSync('./newpath/newfile', 'w')); // make sure path and file exists
let mystream = fs.createWriteStream('./newpath/newfile',{encoding:'binary',flags : 'w'})

//ref2
await new Promise(r=> mystream.on('open'),(r)=>{r()})
let whyohwhy = Buffer.from("Should this be easy?")
mystream.write(whyohwhy,'binary',e=>console.log('Written to ./newpath/newfile'))

})();

参考1：https://stackoverflow.com/a/12809419/1461850
参考2：https://stackoverflow.com/a/12906805/1461850
其他“几乎”的问题：
File and folders create if not exist
Creating a file only if it doesn't exist in Node.js
Create a file if it doesn't already exist
唉，我得到这个错误

Promise {
  <rejected> Error: ENOENT: no such file or directory, open './newpath/newfile'
      at Object.openSync (fs.js:498:3)
      at REPL10:3:17
      at REPL10:9:3
      at Script.runInThisContext (vm.js:133:18)
      at REPLServer.defaultEval (repl.js:486:29)
      at bound (domain.js:416:15)
      at REPLServer.runBound [as eval] (domain.js:427:12)
      at REPLServer.onLine (repl.js:819:10)
      at REPLServer.emit (events.js:388:22)
      at REPLServer.emit (domain.js:470:12) {
    errno: -4058,
    syscall: 'open',
    code: 'ENOENT',
    path: './newpath/newfile'
  }
}
> (node:13988) UnhandledPromiseRejectionWarning: Error: ENOENT: no such file or directory, open './newpath/newfile'
    at Object.openSync (fs.js:498:3)
    at REPL10:3:17
    at REPL10:9:3
    at Script.runInThisContext (vm.js:133:18)
    at REPLServer.defaultEval (repl.js:486:29)
    at bound (domain.js:416:15)
    at REPLServer.runBound [as eval] (domain.js:427:12)
    at REPLServer.onLine (repl.js:819:10)
    at REPLServer.emit (events.js:388:22)
    at REPLServer.emit (domain.js:470:12)
(Use `node --trace-warnings ...` to show where the warning was created)
(node:13988) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:13988) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

是否有一种简单/规范的方法来创建写入初始化writeStream（如果不存在，则创建路径/文件，如果存在，则替换路径/文件）？

node.js

来源：https://stackoverflow.com/questions/74071984/creating-a-path-and-file-write-ready-writestream-if-path-and-file-dont-exist-in

2条答案

按热度按时间

hxzsmxv21#

我刚想到这个，我做的就是扩展Writable，如下所示：

class AsyncPathMakerWriteStream extends Writable {
constructor (basePath, fileName) {
    super()
    this.basePath = basePath
    this.fileName = fileName
    this.fd = null
}
_construct (callback) {
    fs.mkdir(this.basePath, { recursive: true }, err => {
        if (err) {
            callback(err)
        } else {
            fs.open(join(this.basePath, this.fileName), (err, fd) => {
                if (err) {
                    callback(err)
                } else {
                    this.fd = fd
                    callback()
                }
            })
        }
    })
}
_write (chunk, encoding, callback) {
    fs.write(this.fd, chunk, callback)
}
_destroy (err, callback) {
    if (this.fd) {
        fs.close(this.fd, (er) => callback(er || err))
    } else {
        callback(err)
    }
}

}
数据将在流中进行内部缓冲，直到文件打开为止，而不会阻塞主线程。

赞(0）回复(0）举报 2022-12-18

mwkjh3gx2#

我设法用fs-extramodule的ensureFilefunction做到了这一点：

let fs = require('fs-extra')

;(async ()=>{

    await fs.ensureFile('./newpath/newfile').catch(err=>console.log)
    let mystream = fs.createWriteStream('./newpath/newfile',{encoding:'binary',flags : 'w'})
    let whyohwhy = Buffer.from("Why can't this just be easy!")
    mystream.write(whyohwhy,'binary',e=>console.log('Written to ./newpath/newfile'))

})();

不过，我对其他方法很感兴趣......

赞(0）回复(0）举报 2022-12-18

我来回答

如果路径和文件在NodeJS中不存在，则创建路径和文件写就绪writeStream

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