feat: namespaced storage (prefixStorage)

README.md

@@ -28,9 +28,9 @@ Typically, we can choose our data storage based on use-case like a filesystem (N
 ✔️ State snapshot <br>
 ✔️ Driver agnostic watcher <br>
 ✔️ HTTP Storage server (cli and programmatic) <br>
+✔️ Namespaced storage <br>
 <br>
 🚧 Overlay storage (usable for Copy-on-write for read-only storage) <br>
-🚧 Namespaced storage <br>
 🚧 Node FS API (for virtual fs) <br>
 <br>
 
@@ -56,6 +56,7 @@ Typically, we can choose our data storage based on use-case like a filesystem (N
 - [Utils](#utils)
   - [`snapshot(storage, base?)`](#snapshotstorage-base)
   - [`restoreSnapshot(storage, data, base?)`](#restoresnapshotstorage-data-base)
+  - [`prefixStorage(storage, data, base?)`](#prefixstoragestorage-data-base)
 - [Storage Server](#storage-server)
 - [Drivers](#drivers)
   - [`fs` (node)](#fs-node)
@@ -247,6 +248,22 @@ Restore snapshot created by `snapshot()`.
 await restoreSnapshot(storage, { 'foo:bar': 'baz' }, '/etc2')
 ```
 
+### `prefixStorage(storage, data, base?)`
+
+Create a namespaced instance of main storage.
+
+All operations are virtually prefixed. Useful to create shorcuts and limit access.
+
+```js
+import { createStorage, prefixStorage } from 'unstorage'
+
+const storage = createStorage()
+const assetsStorage = prefixStorage(storage, 'assets')
+
+// Same as storage.setItem('assets:x', 'hello!')
+await assetsStorage.setItem('x', 'hello!')
+```
+
 ## Storage Server
 
 We can easily expose unstorage instance to an http server to allow remote connections.

src/index.ts

@@ -1,3 +1,4 @@
 export * from './storage'
 export * from './types'
+export * from './utils'
 export { defineDriver } from './drivers/utils'

src/utils.ts

@@ -0,0 +1,29 @@
+import type { Storage } from './types'
+import { normalizeBase } from './_utils'
+
+const storageKeyProps: (keyof Storage)[] = [
+  'hasItem',
+  'getItem',
+  'setItem',
+  'removeItem',
+  'getMeta',
+  'setMeta',
+  'removeMeta',
+  'getKeys',
+  'clear',
+  'mount',
+  'unmount'
+]
+
+export function prefixStorage (storage: Storage, base: string): Storage {
+  base = normalizeBase(base)
+  if (!base) {
+    return storage
+  }
+  const nsStorage: Storage = { ...storage }
+  for (const prop of storageKeyProps) {
+    // @ts-ignore Better types?
+    nsStorage[prop] = (key: string, ...args) => storage[prop](base + key, ...args)
+  }
+  return nsStorage
+}

test/storage.test.ts

@@ -1,4 +1,4 @@
-import { createStorage, snapshot, restoreSnapshot } from '../src'
+import { createStorage, snapshot, restoreSnapshot, prefixStorage } from '../src'
 import memory from '../src/drivers/memory'
 
 const data = {
@@ -27,3 +27,12 @@ describe('storage', () => {
     expect(onChange).toHaveBeenCalledWith('update', 'mnt:data:foo')
   })
 })
+
+describe('utils', () => {
+  it('prefixStorage', async () => {
+    const storage = createStorage()
+    const pStorage = prefixStorage(storage, 'foo')
+    await pStorage.setItem('x', 'bar')
+    expect(await storage.getItem('foo:x')).toBe('bar')
+  })
+})