@varasto/storage

Type definitions for Varasto JSON key-value store.

• Installation
• Usage
  • Storing items
  • Retrieving items
  • Removing items
  • Searching for entries
  • Updating already existing item
  • Testing whether an item exists or not
  • Listing keys stored in a namespace
  • Listing values stored in a namespace
  • Listing entries stored in a namespace
  • Filtering entries stored in a namespace
  • Map operation

Installation

$ npm install --save @varasto/storage

Usage

This package provides abstract base class for Varasto storage implementations as well as error classes to indicate that an item identifier (either namespace or key) does not pass the slug validation or that an item being updated does not exist.

Usually you don't need to use or install this package directly, but use an storage implementation package instead. Below is an list of storage implementations for different use cases.

Name	Description
cache-storage	Acts as an cache for another storage.
fs-storage	Stores data persistently to hard disk.
memory-storage	Stores data to memory.
multi-storage	Stores data to multiple other storages.
postgres-storage	Stores data to PostgreSQL database.
remote-storage	Stores data to remote server.
redis-storage	Stores data to Redis.
single-file-storage	Stores data to a single file.
sqlite-storage	Stores data to SQLite database.
validator-storage	Acts as an validator for another storage.
web-storage	Stores data to browser storage.

Storing items

set<T extends JsonObject>(
  namespace: string,
  key: string,
  value: T
): Promise<void>

Attempts to store an item identified by namespace and key. Returned promise will fail if an I/O error occurs while storing the item.

Retrieving items

get<T extends JsonObject>(
  namespace: string,
  key: string
): Promise<T | undefined>

Attempts to retrieve an item identified by namespace and key. Returned promise will either resolve into the value, or undefined if item with the given identifier does not exist. The promise will fail if an I/O error occurs while retrieving the item.

Removing items

delete(
  namespace: string,
  key: string
): Promise<boolean>

Attempts to remove an item identified by namespace and key. Returned promise will resolve into a boolean value which tells whether an value with the given identifier existed or not. The promise will fail if an I/O error occurs while removing the item.

Searching for entries

find<T extends JsonObject>(
  namespace: string,
  callback: (value: T, key: string) => boolean
): Promise<[string, T | undefined]>

Returns the first entry from specified namespace to which given callback function returns true for, or undefined if the callback function does not return true for any entry in the namespace.

The promise will fail if an I/O error occurs, or if given namespace is not a valid slug.

Updating already existing item

update<T extends JsonObject>(
  namespace: string,
  key: string,
  value: Partial<T>
): Promise<T>

Attempts to update an already existing item identified by namespace and key by shallowly merging with the given new data. Returned promise will resolve into the new value, or will fail if no such item exists.

Testing whether an item exists or not

has(
  namespace: string,
  key: string
): Promise<boolean>

Returns true if an item identified by namespace and key exists in the storage, or false if it doesn't. The promise will fail if an I/O error occurs while testing whether item exists or not.

Listing keys stored in a namespace

keys(
  namespace: string
): AsyncGenerator<string>

Lists keys of all items stored under an namespace. The promise will fail if an I/O error occurs while listing the keys.

Listing values stored in a namespace

values<T extends JsonObject>(
  namespace: string
): AsyncGenerator<T>

Lists all items stored under an namespace. The promise will fail if an I/O error occurs.

Listing entries stored in a namespace

entries<T extends JsonObject>(
  namespace: string
): AsyncGenerator<[string, T]>

Lists all items stored under an namespace, with the keys they are identified by. The promise will fail if an I/O error occurs.

Filtering entries stored in a namespace

filter<T extends JsonObject>(
  namespace: string,
  callback: (value: T, key: string) => boolean
): AsyncGenerator<[string, T]>

Goes through all entries from the given namespace, returning ones for which the given callback functions returns true for.

The promise will fail if an I/O error occurs, or if given namespace is not a valid slug.

Map operation

map<T extends JsonObject, U extends JsonObject>(
  namespace: string,
  callback: (value: T, key: string) => U
): AsyncGenerator<[string, U]>

Goes through all entries from the given namespace, passing them to the given callback function and returning whatever the callback function returned.

The promise will fail if an I/O error occurs, or if given namespace is not a valid slug.