Nodejs, How to Convert XML to CSV| Javascript

You can check more about xml and json types Nodejs Application

In Javascript, there is no direct solution to convert XML to JSON, We have npm library @wmfs/xml2csv . You can also check other posts on npm command deprecate option is deprecated First, Let’s create a nodejs application using the npm initcommand

npm init
 npm init -Y

This command creates a nodejs application with all default values

Next, Install the @wmfs/xml2csv dependency to an application using the below command

npm install xml2csv --save

This adds dependency in package.json as follows

  "dependencies": {
    "@wmfs/xml2csv": "^1.23.0",
  }

Let’s declare XML file an for this example

 <users>
 <user id="u12">
      <id>12</id>
      <username>john</username>
      <role>admin</role>
      <active>false</active>
      <create_date>2000-10-01</create_date>
</user>
</users>

#How to Convert XML to CSV in Nodejs

• First import module @wmfs/xml2csv and loads module and creates an object xml2csv
• Create an xml2csv object with options object and callback function

Options object contains the following properties

• xmlPath: input XML path location and XML file name
• csvPath : output csv path location
• rootXMLElement: root tag for each XML record to read, In our example user.xml file, We have a user tag that contains data
• headerMap: mapping xml tag to csv columns HeaderMap declaration contains the field definition

[xmlTag, csvHeader, type, parent],

• xmlTag: XML tag to be converted to CSV fields i.e id,username,role,active

• csvHeader: xsv content fields

• type: type of the field date, string, and number

• parent: Optional parent tag of the XML tag

• callback function: The callback called and contains an error and result error- returns an error object if an error result - count of records processed

#Call back example to convert XML to CSV

The callback function is called with the first parameter as an error and the second parameter result.

Example for converting XML to CSV with asynchronous operation

const xml2csv = require("@wmfs/xml2csv");

xml2csv(
  {
    xmlPath: "user.xml",
    csvPath: "csvfile.csv",
    rootXMLElement: "user",
    headerMap: [
      ["id", "id", "integer"],
      ["username", "username", "string"],
      ["role", "role", "string"],
      ["active", "active", "boolean"],
    ],
  },
  function (err, result) {
    console.log(err);
    console.log(result);
  },
);

Output: csvfile.csv file is created with the following data

id,username,role,active
12,"john","admin",false

#Promise example to convert xml to csv in nodejs

Promise.then contains two functions, the First function is executed with a resolved promise and the second function is called with a rejected case Promise.catch contains the error function called for promise error Here is Syntax

promise.then(
  function(result) { // Calls success result  },
  function(error) { // calls an error case }
).catch(function(promiseerror){
  // error case
});

The same above can be rewritten, replace lambda expressions and simplify the code clean.

promise
  .then(
    (result) => {
      console.log("XML to CSV conversion completed", result);
    },
    (error) => {
      console.log("XML to CSV conversion rejected", error);
    },
  )
  .catch((error) => {
    // error case
  });

Here is an example with a simplified version You can check other posts on How to always run some code when a promise is resolved or rejected xml2csvPromise.js:

const xml2csv = require("@wmfs/xml2csv");

xml2csv(
  {
    xmlPath: 'user.xml',
    csvPath: 'csvfile.csv',
    rootXMLElement: 'user',
    headerMap: [
      ['id', 'id', 'integer'],
      ['username', 'username', 'string'],
      ['role', 'role', 'string'],
      ['active', 'active', 'boolean'],


    ]
  },).then((result)=>{
    console.log("XML to CSV conversion completed",result);
  },(err=>{
        console.log("error conversion rejected",err);

  }))
.catch((err)=>{
      console.log("Conversion Failed",err);

}));

#Conclusion

Learned multiple ways to convert xml to CSV with examples.