SaxesStream
NodeJS Streams wrapper around SaxesParser (npm package saxes)
- Single event stream
- Pipable to other streams
- TypeScript declarations
API
Input
Any string/Buffer Saxes would accept.
Output chunk format:
import { SaxesTag } from "saxes";
export type SaxesStreamChunk =
{ event: "opentag", path: string, tag: SaxesTag } |
{ event: "text", path: string, text: string } |
{ event: "closetag", path: string, tag: SaxesTag };
Events
Standard NodeJS Streams events.
Example 1 - Get huge online XML of books and stream parse it into CSV
import { SaxesOptions, SaxesStream, SaxesStreamChunk } from "saxes-stream";
import { Transform, TransformOptions, TransformCallback } from "stream";
import request from "request";
import fs from "fs";
import stringify from "csv-stringify";
/* Source HTTP XML stream */
const httpStream = request(url);
/* SaxesStream XML parser */
const const saxesOptions: SaxesOptions = {
// ...
}
const streamOptions: TransformOptions = {
// ...
}
const parser = new SaxesStream(saxesOptions, streamOptions);
/* Custom Transform Stream to pick the data from XML */
class BookTransform extends Transform {
item: any = {};
// Stream setting
readableObjectMode = true;
writableObjectMode = true;
_transform(chunk: SaxesStreamChunk, encoding: string, callback: TransformCallback) {
/* Save parts by matching path */
if (chunk.event === "text") {
switch (chunk.path) {
case ".books.book.title": this.item["title"] = chunk.text; break;
case ".books.book.content": this.item["content"] = chunk.text; break;
}
}
/* On ending </book> tag emit the completed book object as data (or piped to a next stream) */
if (chunk.event === "closetag") {
switch (chunk.path) {
case ".books.book":
this.push(this.item);
this.item = {};
break;
}
}
callback();
}
}
const bookTransform = new BookTransform();
/* JSON -> CSV Transform Stream */
const csv = stringify({ delimiter: ',' });
/* File Write Stream */
const file = fs.createWriteStream('./books.csv');
/* PIPE ALL THINGS TOGETHER */
httpStream.pipe(parser).pipe(bookTransform).pipe(csv).pipe(file);
