Question

嗨，我有两个CSV文件。

Spas.csv
Customers.csv

Spas.csv

id  | name
...........................
5   | Wasana spa
...........................
7   | Hot spring spa
...........................
8   | Colombo spa
...........................
10  | Sanhida spa
...........................
12  | Waruna spa
...........................

Customers.csv

id  | name  | spaId
........................
1   |Hiran  |5
........................
2   |Hirushi|5
........................
3   |Mishani|8
........................
4   |Chamod |12

从MYSQL DB导出的这两个CSV文件。我想要的是像这样更改spaId文件的Customers.csv。

id  | name  | spaId
........................
1   |Hiran  |1
........................
2   |Hirushi|1
........................
3   |Mishani|3
........................
4   |Chamod |5

这些新的spaId来自 Spas.csv 文件的行号。示例：-id 5位于行1，因此将5替换为1。

如何在nodejs / javaScript中实现此目的。我到目前为止所做的就是这个。

var fs = require('fs')
var csv = require('fast-csv');

fs.createReadStream('spas.csv')
    .pipe(csv())
    .on('data',function(data){
        console.log('DATA',data)
    })
    .on('end',function(data){
        console.log("FIN",data)
    })

基本上，它将控制台记录每一行作为数组，我不知道如何同时写入CSV。

Answer 1

尝试一下：

const fs = require("fs");

const csv = require("fast-csv");

async function getSpasIdMap(filePath){

   return new Promise(function(resolve, reject) {

     let map = {};

     let count = 0;

     let stream = fs.createReadStream(filePath);

     let csvStream = csv({ headers:true })
     .on("data", function(data){
         map[data.id] = ++count;
     })
     .on("error", (e) => {
         reject(e);
     })
     .on("end", function(){
         resolve(map);
     });

     stream.pipe(csvStream);
 })
}

async function computeAndWriteCustomerData(spasSource, customerSource, dest){

  let spasMap = await getSpasIdMap(spasSource);

  let customerStream = fs.createReadStream(customerSource);

  let csvCustomerStream = csv({headers:true})
  .transform(function(row) {
      return `${row.name},${spasMap[row.spaId]}\n`;
  });

  let writableStream = fs.createWriteStream(dest);
  customerStream.pipe(csvCustomerStream);
  csvCustomerStream.pipe(writableStream);
}

async function main() {
    await computeAndWriteCustomerData("spas.csv", "customer.csv", "my.csv");
}

main();

Node.js / javaScript处理CSV文件

1 个答案: