Middlewares

There are 4 types of middlewares that ca be defined to handle your requests:

Common Properties

These properties are available in all the middlewares types

interface BaseMiddleware {
    guard?: (params: UrlParams) => boolean;
    method?: 'GET' | 'POST' | 'PUT' | 'DELETE' | 'PATCH' | 'HEAD' | 'OPTIONS';
    pre?: (request: NextRequestWithParams<T>) => MaybePromise<
        | boolean
        | {
              redirectTo: string | URL;
              statusCode?: number;
          }
    >;
}

prop	desc
`guard`	A function that checks if the given path arguments are valid. If `false` is returned then the middleware is skipped.
`pre`	This is executed before the middleware. It can be useful to check authentication and separate the logic.
`method`	Filter the middleware by the HTTP method. If the method does not match the middleware is skipped.

⚠️ WARNING: The method property is not available on the HostnameMiddleware type.

Path Middleware

This is the standard middleware that is executed when the path is matched.

interface PathMiddleware<T> {
    handler: NextMiddlewareWithParams<T> | Middleware<T>[];
    path: PathMatcher;
    method?: 'GET' | 'POST' | 'PUT' | 'DELETE' | 'PATCH' | 'HEAD' | 'OPTIONS';
    guard?: (params: UrlParams) => boolean;
    pre?: (request: NextRequestWithParams<T>) => MaybePromise<
        | boolean
        | {
              redirectTo: string | URL;
              statusCode?: number;
          }
    >;
}

Example

middleware.ts

const supportedLanguages = ["it", "en"]
const slugs = [...]
 
export default handlePaths([
  {
    path: "/:lang/blog/:slug",
    guard: params => supportedLanguages.includes(params.lang) || slugs.includes(params.slug),
    handler: (req, res, ev) => {
      // do something
 
      return res
    } 
  }
])

Redirect Middleware

The name is quite self-explanatory. This middleware is executed when the path is matched and it redirects to another path. If you need a more advanced redirect logic you can use the PathMiddleware

interface RedirectMiddleware<T> {
    path: PathMatcher;
    method?: 'GET' | 'POST' | 'PUT' | 'DELETE' | 'PATCH' | 'HEAD' | 'OPTIONS';
    guard?: (params: UrlParams) => boolean;
    redirectTo: string | ((req: NextRequestWithParams<T>) => string);
    includeOrigin?: string | boolean;
}

Example Usage

middleware.ts

const supportedLanguages = ["it", "en"]
const slugs = [...]
 
export default handlePaths([
  {
    path: "/app",
    redirectTo: "/dashboard",
  }
])

Rewrite Middleware

This middleware is executed when the path is matched and it rewrites the path to another one.

interface RewriteMiddleware<T> {
    path: PathMatcher;
    method?: 'GET' | 'POST' | 'PUT' | 'DELETE' | 'PATCH' | 'HEAD' | 'OPTIONS';
    guard?: (params: UrlParams) => boolean;
    rewriteTo: string | ((req: NextRequestWithParams<T>) => string);
}

Example Usage

middleware.ts

const supportedLanguages = ["it", "en"]
const slugs = [...]
 
export default handlePaths([
  {
    path: "/",
    rewriteTo: "/marketing",
  }, {
    path: "/dashboard",
    rewriteTo: "/app",
  }
])

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