How to store data in nodejs to xml

Node.js is a popular open source backend JavaScript runtime environment used by many developers to build high-performance and scalable web applications. In many cases, these applications need to store and retrieve data. While Node.js has built-in capabilities for file system operations, storing data in XML files may be more convenient in some cases. The following will introduce how to use Node.js to store data in XML.

1. What is XML?

XML is the abbreviation of Extensible Markup Language (Extensible Markup Language). It is a general markup language used to describe data formats. XML files consist of tags, attributes and text and can be nested to represent complex data structures. XML files are readable and extensible, which makes them a popular format for storing and exchanging data.

2. XML parser in Node.js

To store data in Node.js to XML, you first need a parser that can process XML. There are many Node.js modules that can parse XML, the most popular of which is xml2js. xml2js can convert XML files into JavaScript objects, and JavaScript objects can be written to files through the Node.js module fs. After installing and referencing xml2js, you can convert XML files into JavaScript objects and write JavaScript objects into XML files.

The following is a sample code using xml2js:

const fs = require('fs'); const xml2js = require('xml2js'); const builder = new xml2js.Builder(); const obj = { items: { item: [ { name: 'item 1', price: '10.00', }, { name: 'item 2', price: '20.00', }, ], }, }; const xml = builder.buildObject(obj); fs.writeFileSync('data.xml', xml);

In this example, we construct a JavaScript object that represents a product list containing two products. We use the Builder in xml2js to convert the JavaScript object into an XML string and write it to a file named "data.xml".

3. Reading data from XML

After storing data in XML, we may also need to read data from the XML file. Likewise, the xml2js module can be used to parse data from XML files and convert them into JavaScript objects. The following is a sample code using xml2js:

const fs = require('fs'); const xml2js = require('xml2js'); fs.readFile('data.xml', function(err, data) { const parser = new xml2js.Parser(); parser.parseString(data, function (err, result) { console.dir(result); }); });

In this example, we use the fs module to read a file named "data.xml", and then use Parser in xml2js to parse the file content. Parser converts the XML string into a JavaScript object and passes it to the callback function. In the callback function, we use console.dir to output the JavaScript object so that its contents can be viewed in the console.

4. Conclusion

Node.js can store and read XML files by using the xml2js module. xml2js can convert JavaScript objects to XML strings and XML strings to JavaScript objects. XML files are a convenient and readable data storage format for applications that need to store and retrieve data in Node.js.

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