Custom

If you cannot find a built-in middleware that fits your needs, you can always build your own.

Use createStorageMiddleware to build your own middleware.

API

createStorageMiddleware(config, handler)

Your middleware must provide a configuration object and a handler function.

The configuration object must contain a name to identify the middleware and can optionally contain skipPaths and includePaths.

{
  name: string;
  skipPaths?: string[];
  includePaths?: string[];
}

Like any other middleware, your middleware supports path filtering. They are mutually exclusive and can therefore not be used together.

Simple Example

The following custom middleware adds a random request ID to the context.

import { createStorageMiddleware } from "vs3";

const requestIdMiddleware = createStorageMiddleware(
  { name: "request-id" },
  async () => {
    const id = crypto.randomUUID();
    return { requestId: id };
  },
);

Registration

Register your middleware in your storage configuration like you would with any other middleware.

const storage = createStorage({
  bucket: "my-bucket",
  adapter,
  middlewares: [customMiddleware],
});

Best Practices

1. Keep middleware single-purpose and deterministic.
2. Fail early with explicit errors or responses.
3. Return small, well-named context objects.
4. Use path filters to limit expensive middleware to relevant endpoints.