Stream-xml-editor NPM

stream-xml-editor

npm install stream-xml-editor

This library helps you to transform large XML files (2G+) using streams, therefore you can read values or append new node to file which does not fit in your memory. It uses saxes library under the hood.

Text node values and cdata are both supported

Use cases

Read value

import * as streamPromises from "node:stream/promises"

import { StreamXMLReader } from "stream-xml-editor"

/* Lets assume our xml has structure: 
<Root>
  <Entity>
    <Name>name1</Name>
    <Value>5</Value>
  </Entity>
  <Entity>
    <Name>name2</Name>
    <Value>8</Value>
  </Entity>
</Root> */

async function main() {
    const readable = getYourReadStream()
    const reader = new StreamXMLReader(readable)
    let sum = 0
    reader.addReadingRule("/Root/Entity/Value", "text", (content) => {
        const amount = Number.parseInt(content)
        sum += amount
    })
    reader.start(); // do not forget to start your reader
    await streamPromises.finished(readable) // sum should be 13
}

Append new node

import * as streamPromises from "node:stream/promises"

import { StreamXMLAppender } from "stream-xml-editor"

async function main() {
    const readable = getYourReadStream() // same structure with Entity Value tags
    const writable = getYourWriteStream()
    const appender = new StreamXMLAppender(readable, writeable)
    let sum = 0
    appender.addAppendingRule("/Root/Entity/Value", "text", (content) => {
        const amount = Number.parseInt(content)
        if (amount % 2 == 0) {
            return  {
                value: "<IsEven>true</IsEven>",
                parentNode: "/Root/Entity",
                doIndent: true
            }
        }
        else {
            return  {
                value: "<IsEven>false</IsEven>",
                parentNode: "/Root/Entity",
                doIndent: true
            }
        }
    })
    reader.start(); // do not forget to start your reader
    await streamPromises.finished(readable)
    await streamPromises.finished(writable) // new file will have nodes appended

}