FileStorage plugin

The FileStorage prefix plugin intercepts calls to a file-storage adapter and transparently prefixes all file keys with a configurable string. This enables logical key namespacing without modifying the adapter implementation.

Use cases

• Multi-tenant storage — Prefix file keys with a tenant identifier to isolate files between tenants
• Environment isolation — Separate development, staging, and production file storage
• Directory scoping — Organize files into virtual directories by prepending a path prefix
• Bucket consolidation — Use a single storage bucket/container with namespaced keys instead of multiple buckets

How it works

The withFileStoragePrefix function returns a PluginFn that calls enhance on each adapter method that accepts a file key. When an enhanced method is invoked, the plugin intercepts the call, prepends the configured prefix to the key argument, and forwards the modified arguments to the original method.

The plugin prefixes keys for the following methods:

Method	Key argument	Pattern
getPublicUrl	Second argument (key)	prefix + key
getSignedDownloadUrl	Second argument (key)	prefix + key
getSignedUploadUrl	Second argument (key)	prefix + key
exists	Second argument (key)	prefix + key
getStream	Second argument (key)	prefix + key
getBytes	Second argument (key)	prefix + key
getMetaData	Second argument (key)	prefix + key
add	Second argument (key)	prefix + key
addStream	Second argument (key)	prefix + key
update	Second argument (key)	prefix + key
updateStream	Second argument (key)	prefix + key
put	Second argument (key)	prefix + key
putStream	Second argument (key)	prefix + key
copy	Second argument (source)	prefix + source
copyAndReplace	Second argument (source)	prefix + source
move	Second argument (source)	prefix + source
moveAndReplace	Second argument (source)	prefix + source
removeMany	Second argument (keys)	keys.map(k => prefix + k)
removeByPrefix	Second argument (key)	prefix + key

Copy and move behavior

For the copy, copyAndReplace, move, and moveAndReplace methods, only the source key (the first string argument after context) is prefixed. The destination key is passed through unchanged. This allows copying/moving files to an un-prefixed location.

Usage

import { withPlugin } from "@daiso-tech/core/middleware";
import { MemoryFileStorageAdapter } from "@daiso-tech/core/file-storage/memory-file-storage-adapter";
import { withFileStoragePrefix } from "@daiso-tech/core/file-storage/plugins";

const adapter = new MemoryFileStorageAdapter();

// Apply the prefix plugin
const prefixedAdapter = withPlugin(
    adapter,
    withFileStoragePrefix("tenant-42/"),
);

// The key "avatars/user1.png" is prefixed to "tenant-42/avatars/user1.png"
await prefixedAdapter.add(context, "avatars/user1.png", content);

// Copy preserves the prefix on the source only
await prefixedAdapter.copy(context, "avatars/user1.png", "backups/user1.png");
// -> adapter.copy(context, "tenant-42/avatars/user1.png", "backups/user1.png")

Before/after behavior

Before — File keys are used as-is:

adapter.getBytes(context, "uploads/report.pdf")
→ retrieves "uploads/report.pdf"

After — File keys are automatically prefixed:

adapter.getBytes(context, "uploads/report.pdf")
→ retrieves "prod/uploads/report.pdf"

info

For more information about the withPlugin function and applying plugins to adapters, see the Middleware plugin documentation.

Multiple keys — removeMany

The removeMany method receives an array of keys. The plugin maps over the array, prefixing each entry:

adapter.removeMany(context, ["a.pdf", "b.pdf"]);
// -> adapter.removeMany(context, ["prefix:a.pdf", "prefix:b.pdf"])