@unikvs/writeonly

How to use @unikvs/writeonly, which rejects reads to make storage write-only.

Overview

@unikvs/writeonly Middleware rejects reads to make storage write-only.

Read-direction operations (get / has / stream / decode) are rejected as if the key did not exist, while write-direction operations (set / copy / move) pass through. When allowDelete is false, deletion is also rejected.

• name is WriteOnly.
• isOpen is always true.
• allowDelete defaults to false.

Install with:

npm install @unikvs/writeonly

pnpm add @unikvs/writeonly

yarn add @unikvs/writeonly

bun add @unikvs/writeonly

nub add @unikvs/writeonly

aube add @unikvs/writeonly

Usage

WriteOnly implements IMiddleware. Pass it to UniKvs with use().

import { WriteOnly } from "@unikvs/writeonly";

WriteOnly

Middleware that rejects reads to make storage write-only.

Constructor arguments:

The following stores a value:

import { Memory } from "@unikvs/memory";
import { WriteOnly } from "@unikvs/writeonly";
import * as unikvs from "unikvs";

const kvs = new unikvs.Builder<{
  foo: unikvs.Value<Uint8Array>;
}>()
  .use(new WriteOnly())
  .persist(new Memory())
  .build();

await kvs.open();
await kvs.set("foo", new Uint8Array([0, 1, 2]));
await kvs.close();

Data types

• The write direction performs no conversion and passes values through.
• copy and move are allowed as write-direction operations because they do not return values.
• The read direction always fails, as if the key did not exist.
• Deletion is controlled by use(): when allowDelete is false, delete and clear are rejected.

Errors

Errors thrown by this package:

WriteOnlyDeleteNotAllowedError

Meaning

Thrown when delete is called while allowDelete is false.

How to fix

Pass allowDelete: true when deletion is needed.

WriteOnlyClearNotAllowedError

Meaning

Thrown when clear is called while allowDelete is false.

How to fix

Pass allowDelete: true when clearing everything is needed.

KeyNotFoundError

Meaning

Thrown when a read-direction operation (get / has / stream / decode) is called. This is the shared @unikvs/core error.

How to fix

Do not use this middleware when reads are needed.

Example

Catching KeyNotFoundError:

import { KeyNotFoundError } from "@unikvs/writeonly";

try {
  const data = await kvs.get("foo");
} catch (ex) {
  if (ex instanceof KeyNotFoundError) {
    console.log("reads are not allowed");
  } else {
    throw ex;
  }
}