使用 Node js /javascript 中的 Promise 从 fs.readdir 返回值

发布于 2025-01-10 10:31:18 字数 1199 浏览 0 评论 0原文

function fileType() {
  return new Promise((resolve, reject) => {
    let Fields = fs.readdir(
      path.resolve(__dirname, "access"),
      (err, files) => {
        if (err) {
          reject(err);
          return;
        } else {
          files.map((file) => {
            return file.split(".").slice(0, -1).join(".");
          });
        }
      }
    );
    resolve(Fields);
  });
}

async function ambitious(data) {
  let fields = [];

  if (data.collections) {
   fields= await fileType();
  } else {
     if(data.types.access){
       fields.push(data.config.access);
     }
     else{
      fields= await fileType();
     }
  }

  return {
    data_name: data.name,
    data_access: data.config,
    data_encrypted: data.encrypt,
    data_fields: fields,
  };
}

在这里，我尝试从 if 语句返回字段值并将其存储在 data_fields 中，

这里的问题是我从 else 语句获取值，但是当我尝试从 If 语句返回值时，它显示未定义，

因为我想阅读所有内容访问内存在的文件并删除文件扩展名，作为数组，我想将其存储在 data_fields 中，

例如，如果文件存在于访问内存中，

let files=[ 'config.sql','admin.xml', 'user_manual.txt' ]

出于此目的，我使用 split 和 slice 来删除所有扩展名并返回数组中的数据data_fields 中的格式

我没有知道如何从 fs.readdir 返回值并将其存储在 data_fields 中

原文

function fileType() {
  return new Promise((resolve, reject) => {
    let Fields = fs.readdir(
      path.resolve(__dirname, "access"),
      (err, files) => {
        if (err) {
          reject(err);
          return;
        } else {
          files.map((file) => {
            return file.split(".").slice(0, -1).join(".");
          });
        }
      }
    );
    resolve(Fields);
  });
}

async function ambitious(data) {
  let fields = [];

  if (data.collections) {
   fields= await fileType();
  } else {
     if(data.types.access){
       fields.push(data.config.access);
     }
     else{
      fields= await fileType();
     }
  }

  return {
    data_name: data.name,
    data_access: data.config,
    data_encrypted: data.encrypt,
    data_fields: fields,
  };
}

Here I am trying to return field value from the if statement and store it in the data_fields

here problem is I am getting the values from the else statement but when I am trying to return value from If statement its showing undefined

As I want to read all the files which are present inside the access and remove the file extension and as an array I want to store it in data_fields

for eg if files are present inside access

let files=[ 'config.sql','admin.xml', 'user_manual.txt' ]

for that purpose I used split and slice to remove all the extension and return data in array format in data_fields

I don't know how to return value from fs.readdir and store it in data_fields

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昵称有卵用 2025-01-17 10:31:19

Node 已经提供了 fs API 的 Promise 版本。您不需要将回调版本包装在 Promise 中。

import { promises } from "fs";

async function fileType () {
    let files = await promises.readdir(path.resolve(__dirname, "access"));
    return files.map( file => file.split(".").slice(0, -1).join("."));
}

Node already offers a Promise version of the fs API. You don't need to wrap the callback version in a Promise.

import { promises } from "fs";

async function fileType () {
    let files = await promises.readdir(path.resolve(__dirname, "access"));
    return files.map( file => file.split(".").slice(0, -1).join("."));
}

回复收藏 0 原文

彡翼 2025-01-17 10:31:19

尝试这样

function fileType() {
  return new Promise((resolve, reject) => {
    fs.readdir(
      path.resolve(__dirname, "access"),
      (err, files) => {
        if (err) {
          reject(err);
        } else {
          resolve(files.map((file) => { // resolve here
            return file.split(".").slice(0, -1).join(".");
          }))
        }
      }
    );
    // if you resolve you promise here, you resolve it before the readdir has been resolved itself.
  });
}

Try like this

function fileType() {
  return new Promise((resolve, reject) => {
    fs.readdir(
      path.resolve(__dirname, "access"),
      (err, files) => {
        if (err) {
          reject(err);
        } else {
          resolve(files.map((file) => { // resolve here
            return file.split(".").slice(0, -1).join(".");
          }))
        }
      }
    );
    // if you resolve you promise here, you resolve it before the readdir has been resolved itself.
  });
}

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