如何使用节点js将新列添加到csv文件 [英] How to add new column to csv file using node js

问题描述

我已经使用node.js npm软件包fast-csv尝试了此操作，但是没有解决方案，我可以成功读取csv文件，现在需要在现有的csv文件中添加新列.

I already tried this using node.js npm package fast-csv, but I don't get a solution, I can read csv file successfully, now I need to add a new column to my existing csv file.

我的问题:

如何在csv文件中添加新列?如何更新csv?

How to add new column to csv file? How to update csv?

var csv = require("fast-csv");
var fs = require('fs');
var stream = fs.createReadStream("file1.csv");
var service = 'https://maps.googleapis.com/maps/api/distancematrix/json?origins=53.78943,-0.9985&destinations=53.540867,-0.510699&mode=driving&language=en-US';
var source = [];
var dest = [];
var distance = require('google-distance');

distance.apiKey = '************';
var i = 1;
csv
    .fromStream(stream, { headers: true })
    .on("data", function(data) {
        //get source and distance array
        source = data.SourceLatLong;
       dest = data.DestBREPLatLong;
        //print source and destinatoon
        console.log(source);
        console.log(dest);
        distance.get({
                // index: i,
                origin: source,
                destination: dest,
                units: 'imperial'
            },

            function(err, map_data) {

                if (err) return console.log(err);
                //console.log(map_data);
                //console miles of aff
                console.log('source lat long ' + ':' + data.SourceLatLong + ' , ' + 'Dest lat long' + ':' + data.DestBREPLatLong + ',' + ' distance ' + ':' + map_data.distance + ' ' + i++);

            });
    })

.on("end", function() {
    console.log("done");
});

在上面的程序中，我使用filecsv file1.csv，从中获取两列SourceLatLong和DestLatLong，并以英里为单位计算距离.现在，我需要在文件.csv

In the above program I use the filecsv file1.csv ,from i take two columns SourceLatLong and DestLatLong and I calculate distance in miles. Now I need to add new miles columns to my file .csv

推荐答案

使用csv-parser软件包而不是fast-csv，并使用json2csv将json解析为csv.

Use csv-parser package instead of fast-csv, and json2csv for json to csv parsing.

您要做的是使用csv-parser将csv的每一行转换为json，在结果json对象中添加一个新字段，针对每一行执行此操作，将结果放入数组中，将该数组转换为带有json2csv包的csv.

What you want to do is to convert each row of the csv to json using csv-parser, add a new field into the resulting json object, do this for each row, put the result in an array, convert that array into csv with json2csv package.

这是代码:

var csv = require('csv-parser');
var fs = require('fs');
var json2csv = require('json2csv');
var dataArray = [];

fs.createReadStream('your-original-csv-file.csv')
  .pipe(csv())
  .on('data', function (data) {
    data.newColumn = newColumnValue;
    dataArray.push(data);
  })
  .on('end', function(){
    var result = json2csv({ data: dataArray, fields: Object.keys(dataArray[0]) });
    fs.writeFileSync(fileName, result);
  });

fs.writeFileSync仍然会覆盖原始文件，因此您也可以将其保存到原始csv文件中.

fs.writeFileSync overrides the original file anyway, so you can also save into the original csv file.

这篇关于如何使用节点js将新列添加到csv文件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！