使用Ramda从许多文件中收集JSON数据

Question

首次推动我自己在一个小型Node项目上使用Ramda，并且我遇到了困难。我如何用Ramda编写代码？

const dataObject = {}; 
const promises = []; 

for (let i = 0; i < myTableNames.length; i++) { 
    const tableName = myTableNames[i]; 
    const newPromise = new Promise((resolve, reject) => { 
     fs.readFile(`./tables/${filename}.json`, (err, content) => { 
      if (err) { 
       return reject(); 
      } 
      dataObject[tableName] = JSON.parse(content); 
      return resolve(); 
     }); 
    }); 
    promises.push(newPromise); 
} 

Promise.all(promises).then(() => { 
    console.log(dataObject); 
}); 

Answer 1

如果使用节点8节，你可以不喜欢这样。 Demo

// promisify fs.readFile 
const readFile = require('util').promisify(fs.readFile) 
const getFilePath = tableName => `./tables/${tableName}.json` 
const loadFileContents = pipe(getFilePath, pipeP(readFile, JSON.parse)) 

// 1. Map each table name into promise that resolves with 
// parsed file content 
// 2. Wait for all 
// 3. Build object using table names as keys and contents as 
// as values 
Promise.all(map(loadFileContents, myTableNames)) 
    .then(zipObj(myTableNames)) 
    .then(console.log) 

Answer 2

随着fs-extra：

const fs = require('fs-extra'); 

const readFile = fileName => fs.readFile(`./tables/${fileName}.json`); 
const buildResults = (files) => { 
    const build = (acc, json, idx) => R.assoc(myTableNames[idx], JSON.parse(json), acc); 
    return R.reduce(build, {}, files); 
} 

Promise.all(R.map(readFile, myTableNames)) 
    .then(buildResults) 
    .then(data => console.log(data));