@unikvs/passthrough

Explains how to use @unikvs/passthrough, which passes data through without transforming it.

Overview

@unikvs/passthrough is a Transformer plugin that passes input through without transforming it. Transformer

encode and decode return the data they receive, and getEncodable and getDecodable return streams that pass chunks through. They affect neither the contents of the data nor the chunk boundaries.

This transformer is always open. No explicit open or close is needed; isOpen always returns true and name is always "PassThrough".

Install it as follows.

npm install @unikvs/passthrough

pnpm add @unikvs/passthrough

yarn add @unikvs/passthrough

bun add @unikvs/passthrough

nub add @unikvs/passthrough

aube add @unikvs/passthrough

Usage

Register it with appendTransformer. It adds a no-op pipeline to the storages registered after it.

import { PassThrough } from "@unikvs/passthrough";
import { Memory } from "@unikvs/memory";
import { UniKvs, type PlainValue } from "unikvs";

const kvs = UniKvs.config<{ greeting: PlainValue<string> }>()
  .appendTransformer(new PassThrough())
  .appendStorage(new Memory())
  .create();

await kvs.open();

await kvs.set("greeting", "hello");
const greeting = await kvs.get("greeting");

await kvs.close();

Streams

getEncodable and getDecodable return a TransformStream that emits its input unchanged. Neither the chunk boundaries nor the references change. An empty stream completes empty.

Use Cases

Use it to turn a transformer on or off with conditional branching. To turn it off, replace it with PassThrough instead of removing it from its position. You can switch a transformation on and off based on the environment or configuration without changing the pipeline structure.

import { Compression } from "@unikvs/compression";
import { PassThrough } from "@unikvs/passthrough";
import { Memory } from "@unikvs/memory";
import { UniKvs, type Value } from "unikvs";

// Assumed to come from configuration or an environment variable.
const enableCompression = true;
const transformer = enableCompression ? new Compression("gzip") : new PassThrough();

const kvs = UniKvs.config<{ data: Value<Uint8Array<ArrayBuffer>> }>()
  .appendTransformer(transformer)
  .appendStorage(new Memory())
  .create();

await kvs.open();

await kvs.set("data", Uint8Array.from([0, 1, 2]));
const data = await kvs.get("data");

await kvs.close();

Compression and PassThrough both implement ITransformer, so you can swap them at the same position.

Notes

• Because it does not transform data, using it alone does not change stored values.
• To log reads and writes, use @unikvs/debug instead. @unikvs/passthrough neither logs data nor reads variables.