@odms/streamutils

Streamutils

A collection of simple stream implementations for building data pipelines.

Latest Update: v0.3

• refactor into monorepo
• add jq package
• update node-jq, remove patch
• add redis package

Usage

check out this example here: examples/example-1

Let's say you have some input tokens in this form:

token.txt

"Erfurt"
"Ansbach"

You then build your pipeline like this:

import { json, split, toString } from "@odms/streamutils";
import { Transform } from "node:stream";
import { pipeline } from "node:stream/promises";

pipeline(
  process.stdin,
  toString(),
  split("\n"),
  json.parse(),

  // turn each chunk into an object with property 'city'
  new Transform({
    objectMode: true,
    transform: (city: string, _, callback) => {
      callback(null, { city });
    },
  }),

  json.toLines(),
  process.stdout
);

Explanation:

• process.stdin – read from stdin
• toString – convert input Buffer into string
• split – split the input chunk into multiple chunks using newline
• json.parse – remove outer double quotes
• ... here comes your custom stream ...
• json.toLines – stringify into line-json
• process.stdout – write to stdout

Run pipeline:

# cd examples/example-1
# bun install
cat token.txt | bun index.ts

This will produce this output:

{"city":"Erfurt"}
{"city":"Ansbach"}

Documentation

jq

Transform the stream using jq.

import { jq } from "@odms/streamutils";

pipeline(process.stdin, jq(".filter[].items"), process.out);

Thanks to node-js. For filter syntax, refer to the jq manual.

Parameters

• filter: string
  filter used to work on the json

  example: .data[] | {id,name}

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