如何使用 Node.js 將 JSON 數組轉換為 CSV？

Question

我想轉換具有值數組的 json 。 響應.json

{
"rows": [
[
  "New Visitor",
  "(not set)",
  "(not set)",      
  "0"
],
[
  "New Visitor",
  "(not set)",
  "(not set)",
  "mobile"      
],
[
  "New Visitor",
  "(not set)",
  "(not set)",
  "mobile"    
],
  [
    "New Visitor",
    "(not set)",
    "(not set)",
   "mobile",      
  ]
 ]
}

現在我想把這些數據轉換成。 名稱.csv

 "New Visitor","(not set)","(not set)","0"
 "New Visitor","(not set)","(not set)","mobile"        
 "New Visitor","(not set)","(not set)","mobile"    
 "New Visitor","(not set)","(not set)","mobile"

請給我使用 Node.js 的建議。

Answer 1

像這樣自己做：

'use strict';

var fs = require('fs');

let myObj = {
  "rows": [
    [
      "New , Visitor",
      "(not set)",
      "(not set)",
      "0"
    ],
    [
      "New Visitor",
      "(not set)",
      "(not set)",
      "mobile"
    ],
    [
      "New Visitor",
      "(not set)",
      "(not set)",
      "mobile"
    ],
    [
      "New Visitor",
      "(not set)",
      "(not set)",
      "mobile",
    ]
  ]
}

// 1. One way - if you want the results to be in double quotes and you have comas inside

// choose another string to temporally replace commas if necessary
let stringToReplaceComas = '!!!!';

myObj.rows.map((singleRow) => {
  singleRow.map((value, index) => {
    singleRow[index] = value.replace(/,/g, stringToReplaceComas);
  })
})

let csv = `"${myObj.rows.join('"\n"').replace(/,/g, '","')}"`;
// // or like this
// let csv = `"${myObj.rows.join('"\n"').split(',').join('","')}"`;

csv = csv.replace(new RegExp(`${stringToReplaceComas}`, 'g'), ',');

// // 2. Another way - if you don't need the double quotes in the generated csv and you don't have comas in rows' values
// let csv = myObj.rows.join('\n')

fs.writeFile('name.csv', csv, 'utf8', function(err) {
  if (err) {
    console.log('Some error occured - file either not saved or corrupted file saved.');
  } else {
    console.log('It\'s saved!');
  }
});

使用庫

例如。 https://github.com/mrodrig/json-2-csv ， https://github.com/wdavidw/node-csv ， https://github.com/wdavidw/node-csv-stringify

使用 json-2-csv 的示例（ https://github.com/mrodrig/json-2-csv ）

'use strict';

const converter = require('json-2-csv');

let myObj = {
  "rows": [
    {
      value1: "New Visitor",
      value2: "(not set)",
      value3: "(not set)",
      value4: "0"
    },
    {
      value1: "New Visitor",
      value2: "(not set)",
      value3: "(not set)",
      value4: "mobile"
    },
    {
      value1: "New Visitor",
      value2: "(not set)",
      value3: "(not set)",
      value4: "mobile"
    },
    {
      value1: "New Visitor",
      value2: "(not set)",
      value3: "(not set)",
      value4: "mobile",
    }
  ]
}

let json2csvCallback = function (err, csv) {
    if (err) throw err;
    fs.writeFile('name.csv', csv, 'utf8', function(err) {
      if (err) {
        console.log('Some error occured - file either not saved or corrupted file saved.');
      } else {
        console.log('It\'s saved!');
      }
    });
};

converter.json2csv(myObj.rows, json2csvCallback, {
  prependHeader: false      // removes the generated header of "value1,value2,value3,value4" (in case you don't want it)
});

使用 csv-stringify 的示例（ https://github.com/wdavidw/node-csv-stringify ）

'use strict';

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

let myObj = {
  "rows": [
    [
      "New Visitor",
      "(not set)",
      "(not set)",
      "0"
    ],
    [
      "New Visitor",
      "(not set)",
      "(not set)",
      "mobile"
    ],
    [
      "New Visitor",
      "(not set)",
      "(not set)",
      "mobile"
    ],
    [
      "New Visitor",
      "(not set)",
      "(not set)",
      "mobile",
    ]
  ]
}

stringify(myObj.rows, function(err, output) {
  fs.writeFile('name.csv', output, 'utf8', function(err) {
    if (err) {
      console.log('Some error occured - file either not saved or corrupted file saved.');
    } else {
      console.log('It\'s saved!');
    }
  });
});

Answer 2

三個簡單的步驟：閱讀。 轉換。 寫。

第一步：閱讀。

如果您需要從文件中讀取 JSON（如您在帖子中包含的文件名response.json ），您將需要Node.js FileSystem API ：

const fs = require('fs');                          // Require Node.js FileSystem API.
const JSONFile = fs.readFileSync('response.json'); // Read the file synchronously.

注意：如果您願意，可以使用fs.readFile()異步讀取文件並在回調函數中執行轉換。

第 2 步：轉換。

無論您是從本地文件讀取 JSON 還是從服務器獲取它，您都需要首先使用JSON.parse方法將其解析為普通的舊 JavaScript 對象：

const JSONasPOJO = JSON.parse(JSONFile); // Parse JSON into POJO.

然后對子數組和父數組執行一系列連接：
請參閱下面的編輯

/* THIS IS UNNECESSARY FOR "COMMA" SEPARATED VALUES
const CSVString = JSONasPOJO
    .rows                    // Get `rows`, which is an array.
    .map(                    // Map returns a new array.
        row => row.join(',') // Each child array becomes a comma-separated string.  
     )                    
    .join('\n');             // Parent array becomes a newline-separated string...
                             // ...of comma-separated strings.
                             // It is now a single CSV string!
*/

編輯：

雖然前面的代碼肯定有效，但沒有必要在子數組上使用.map和.join 。 正如@Relu 演示的那樣，父數組上的單個.join就足夠了，因為 JavaScript 會默認自動將子數組轉換為逗號分隔的字符串，因為.join必須返回一個字符串並且不能包含任何子數組。

如果你想用逗號以外的東西連接子數組，你可以使用上面的模式。

否則：

var CSVString = JSONasPOJO.rows.join('\n'); // Array becomes a newline-separated...
                                            // ...string of comma-separated strings.
                                            // It is now a single CSV string!

在這里，我們可以看到這種轉換在起作用：

 const JSONasPOJO = { "rows": [ [ "New Visitor", "(not set)", "(not set)", "0" ], [ "New Visitor", "(not set)", "(not set)", "mobile" ], [ "New Visitor", "(not set)", "(not set)", "mobile" ], [ "New Visitor", "(not set)", "(not set)", "mobile" // NOTE: Here I removed a trailing comma, // ...which is invalid JSON! ] ] } const CSVString = JSONasPOJO.rows.join('\\n'); console.log(CSVString);

第三步：寫。

再次使用 FileSystem API，寫入文件，並記錄錯誤或成功消息：

fs.writeFile('name.csv', CSVString, err => {
    if (err) return console.log(err);
    console.log('FILE SUCCESSFULLY WRITTEN!\n');
});

注意：在這里，我演示了使用回調記錄我的錯誤和成功消息的異步模式。 如果您願意，可以使用fs.writeFileSync()同步寫入文件。

把這一切放在一起

我喜歡在我的 Node.js 腳本中添加大量的console.log()消息。

const fs = require('fs');

const inFilename  = 'response.json',
      outFilename = 'name.csv';

console.log(`Preparing to read from ${inFilename} …`);

const JSONContents = fs.readFileSync(inFilename);

console.log(`READ:\n${JSONContents}`);
console.log('Preparing to parse as JSON …');

const JSONasPOJO = JSON.parse(JSONContents);

console.log(`PARSED:\n${JSONasPOJO}`);
console.log('Preparing to convert into CSV …');

const CSVString = JSONasPOJO.rows.join('\n');

console.log(`CONVERTED:\n${CSVString}`);
console.log(`Preparing to write to ${outFilename} …`);

fs.writeFile(outFilename, CSVString, err => {
    if (err) return console.error(err);
    console.log('FILE SUCCESSFULLY WRITTEN!');
});

Answer 3

在嘗試使用該庫幾個小時后，我最終編寫了自己的庫。 https://github.com/KhanhPham2411/simple-node-csv

import { SimpleNodeCsv } from './simple-node-csv';

SimpleNodeCsv.obj2csv({a: 1, b:2}, ",");

// output
// "a","b"
// 1,2

Answer 4

我不了解你們，但我喜歡無需大量額外配置即可按預期工作的小包，嘗試使用 jsonexport，我認為它是最好的模塊，適用於對象、數組等。它的快！

安裝

npm i --save jsonexport

用法

const jsonexport = require('jsonexport');
const fs = require('fs');

jsonexport([{
  value1: "New Visitor",
  value2: "(not set)",
  value3: "(not set)",
  value4: "0"
},
{
  value1: "New Visitor",
  value2: "(not set)",
  value3: "(not set)",
  value4: "mobile"
},
{
  value1: "New Visitor",
  value2: "(not set)",
  value3: "(not set)",
  value4: "mobile"
},
{
  value1: "New Visitor",
  value2: "(not set)",
  value3: "(not set)",
  value4: "mobile",
}], function(err, csv) {
  if (err) return console.error(err);
  fs.writeFile('output.csv', csv, function(err) {
    if (err) return console.error(err);
    console.log('output.csv saved');
  });
});

https://github.com/kauegimenes/jsonexport

Answer 5

我想分享從 json 數組構建 csv 字符串的最簡單方法：

 const data = [ { a: 1, b: new Date(), c: 'a text' }, { a: 1, b: new Date(), c: `string with return carrier and emoji 😂 ` } ] const header = Object.keys(data[0]).map(_ => JSON.stringify(_)).join(';') + '\\n' const outData = data.reduce((acc, row) => { return acc + Object.values(row).map(_ => JSON.stringify(_)).join(';') + '\\n' }, header) console.log(outData)

將打印此字符串：

"a";"b";"c"
1;"2020-03-25T08:49:04.280Z";"a text"
1;"2020-03-25T08:49:04.280Z";"string\n  with\n  return\n  carrier\n  and emoji 😂\n  "