Merge pull request #195 from bitgopatmcl/router-api-updates

feat: update typed-express-router api
BitGo · Aug 11, 2022 · 6e4f9f9 · 6e4f9f9
2 parents 2d43885 + 4be80a7
commit 6e4f9f9
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diff --git a/packages/typed-express-router/README.md b/packages/typed-express-router/README.md
@@ -5,12 +5,13 @@ A thin wrapper around Express's `Router`
 ## Goals
 
 - Define Express routes that are associated with routes in an api-ts `apiSpec`
-- Augment the existing Express request with the decoded request object
+- Augment the existing Express request with the decoded request object and api-ts route
+  metadata
 - Augment the existing Express response with a type-checked `encode` function
 - Allow customization of what to do on decode/encode errors, per-route if desired
 - Allow action to be performed after an encoded response is sent, per-route if desired
-- Allow routes to be defined with path that is different than the one specified in the
-  `httpRoute` (e.g. for aliases)
+- Allow routes to define alias routes with path that is different than the one specified
+  in the `httpRoute`
 - Follow the express router api as closely as possible otherwise
 
 ## Non-Goals
@@ -53,25 +54,15 @@ will enforce types on the payload and encode types appropriately (e.g.
 `BigIntFromString` will be converted to a string). The exported `TypedRequestHandler`
 type may be used to infer the parameter types for these functions.
 
-### Aliased routes
+### Route aliases
 
-If more flexibility is needed in the route path, the `getAlias`-style route functions
-may be used. They take a path that is directly interpreted by Express, but otherwise
-work like the regular route methods:
+If more flexibility is needed in the route path, a `routeAliases` function may be
+provided to match multiple paths. These paths may use the full Express matching syntax,
+but take care to preserve any path parameters or else you will likely get decode errors.
 
 ```ts
-typedRouter.getAlias('/oldDeprecatedHelloWorld', 'hello.world', [HelloWorldHandler]);
-```
-
-### Unchecked routes
-
-For convenience, the original router's `get`/`post`/`put`/`delete` methods can still be
-used via `getUnchecked` (or similar):
-
-```ts
-// Just a normal express route
-typedRouter.getUnchecked('/api/foo/bar', (req, res) => {
-  res.send(200).end();
+typedRouter.get('hello.world', [HelloWorldHandler], {
+  routeAliases: ['/oldDeprecatedHelloWorld'],
 });
 ```
 
@@ -105,6 +96,31 @@ typedRouter.get('hello.world', [HelloWorldHandler], {
 });
 ```
 
+### Unchecked routes
+
+If you need custom behavior on decode errors that is more involved than just sending an
+error response, then the unchecked variant of the router functions can be used. They do
+not fail and call `onDecodeError` when a request is invalid. Instead, they will still
+populate `req.decoded`, except this time it'll contain the
+`Either<Errors, DecodedRequest>` type for route handlers to inspect.
+
+```ts
+// Just a normal express route
+typedRouter.getUnchecked('hello.world', (req, res) => {
+  if (E.isLeft(req.decoded)) {
+    console.warn('Route failed to decode! Continuing anyway');
+  })
+
+  res.send(200).end();
+});
+```
+
+### Router middleware
+
+Middleware added with `typedRouter.use()` is ran just after the request is decoded but
+before it is validated, even on checked routes. It'll have access to `req.decoded` in
+the same way that unchecked routes do.
+
 ### Other usage
 
 Other than what is documented above, a wrapped router should behave like a regular

diff --git a/packages/typed-express-router/src/index.ts b/packages/typed-express-router/src/index.ts
@@ -5,9 +5,12 @@ import { pipe } from 'fp-ts/function';
 import { defaultOnDecodeError, defaultOnEncodeError } from './errors';
 import { apiTsPathToExpress } from './path';
 import {
-  AddAliasRouteHandler,
   AddRouteHandler,
+  AddUncheckedRouteHandler,
   Methods,
+  UncheckedRequestHandler,
+  WrappedRequest,
+  WrappedResponse,
   WrappedRouteOptions,
   WrappedRouter,
   WrappedRouterOptions,
@@ -18,6 +21,7 @@ export type {
   OnDecodeErrorFn,
   OnEncodeErrorFn,
   TypedRequestHandler,
+  UncheckedRequestHandler,
   WrappedRouter,
   WrappedRouteOptions,
   WrappedRouterOptions,
@@ -64,72 +68,94 @@ export function wrapRouter<Spec extends ApiSpec>(
     onDecodeError = defaultOnDecodeError,
     onEncodeError = defaultOnEncodeError,
     afterEncodedResponseSent = () => {},
-  }: WrappedRouteOptions<HttpRoute>,
+  }: WrappedRouteOptions,
 ): WrappedRouter<Spec> {
-  function makeAddAliasRoute<Method extends Methods>(
+  const routerMiddleware: UncheckedRequestHandler[] = [];
+
+  function makeAddUncheckedRoute<Method extends Methods>(
     method: Method,
-  ): AddAliasRouteHandler<Spec, Method> {
-    return (path, apiName, handlers, options) => {
+  ): AddUncheckedRouteHandler<Spec, Method> {
+    return (apiName, handlers, options) => {
       const route: HttpRoute = spec[apiName as keyof Spec]![method]!;
-      const wrapReqAndRes: express.RequestHandler = (req, res, next) => {
-        pipe(
-          route.request.decode(req),
-          E.matchW(
-            (errs) => (options?.onDecodeError ?? onDecodeError)(errs, req, res),
-            (decoded) => {
-              // Gotta cast to mutate this in place
-              (req as any).decoded = decoded;
-              (res as any).sendEncoded = (
-                status: keyof typeof route['response'],
-                payload: any,
-              ) => {
-                try {
-                  const codec = route.response[status];
-                  if (!codec) {
-                    throw new Error(`no codec defined for response status ${status}`);
-                  }
-                  const statusCode =
-                    typeof status === 'number'
-                      ? status
-                      : KeyToHttpStatus[status as keyof KeyToHttpStatus];
-                  if (statusCode === undefined) {
-                    throw new Error(`unknown HTTP status code for key ${status}`);
-                  } else if (!codec.is(payload)) {
-                    throw new Error(
-                      `response does not match expected type ${codec.name}`,
-                    );
-                  }
-                  const encoded = codec.encode(payload);
-                  res.status(statusCode).json(encoded).end();
-                  (options?.afterEncodedResponseSent ?? afterEncodedResponseSent)(
-                    status,
-                    payload,
-                    req,
-                    res,
-                  );
-                } catch (err) {
-                  (options?.onEncodeError ?? onEncodeError)(err, req, res);
-                }
-              };
-              next();
-            },
-          ),
-        );
+      const wrapReqAndRes: UncheckedRequestHandler = (req, res, next) => {
+        const decoded = route.request.decode(req);
+        req.decoded = decoded;
+        req.apiName = apiName;
+        req.httpRoute = route;
+        res.sendEncoded = (
+          status: keyof typeof route['response'],
+          payload: unknown,
+        ) => {
+          try {
+            const codec = route.response[status];
+            if (!codec) {
+              throw new Error(`no codec defined for response status ${status}`);
+            }
+            const statusCode =
+              typeof status === 'number'
+                ? status
+                : KeyToHttpStatus[status as keyof KeyToHttpStatus];
+            if (statusCode === undefined) {
+              throw new Error(`unknown HTTP status code for key ${status}`);
+            } else if (!codec.is(payload)) {
+              throw new Error(`response does not match expected type ${codec.name}`);
+            }
+            const encoded = codec.encode(payload);
+            res.status(statusCode).json(encoded).end();
+            (options?.afterEncodedResponseSent ?? afterEncodedResponseSent)(
+              statusCode,
+              payload,
+              req as WrappedRequest,
+              res as WrappedResponse,
+            );
+          } catch (err) {
+            (options?.onEncodeError ?? onEncodeError)(
+              err,
+              req as WrappedRequest,
+              res as WrappedResponse,
+            );
+          }
+        };
+        next();
       };
 
-      router[method](path, [wrapReqAndRes, ...(handlers as express.RequestHandler[])]);
+      const middlewareChain = [
+        wrapReqAndRes,
+        ...routerMiddleware,
+        ...handlers,
+      ] as express.RequestHandler[];
+
+      const path = spec[apiName as keyof typeof spec]![method]!.path;
+      router[method](apiTsPathToExpress(path), middlewareChain);
+
+      options?.routeAliases?.forEach((alias) => {
+        router[method](alias, middlewareChain);
+      });
     };
   }
 
   function makeAddRoute<Method extends Methods>(
     method: Method,
   ): AddRouteHandler<Spec, Method> {
     return (apiName, handlers, options) => {
-      const path = spec[apiName as keyof typeof spec]![method]!.path;
-      return makeAddAliasRoute(method)(
-        apiTsPathToExpress(path),
+      const validateMiddleware: UncheckedRequestHandler = (req, res, next) => {
+        pipe(
+          req.decoded,
+          E.matchW(
+            (errs) => {
+              (options?.onDecodeError ?? onDecodeError)(errs, req, res);
+            },
+            (value) => {
+              req.decoded = value;
+              next();
+            },
+          ),
+        );
+      };
+
+      return makeAddUncheckedRoute(method)(
         apiName,
-        handlers,
+        [validateMiddleware, ...handlers],
         options,
       );
     };
@@ -144,14 +170,13 @@ export function wrapRouter<Spec extends ApiSpec>(
       post: makeAddRoute('post'),
       put: makeAddRoute('put'),
       delete: makeAddRoute('delete'),
-      getAlias: makeAddAliasRoute('get'),
-      postAlias: makeAddAliasRoute('post'),
-      putAlias: makeAddAliasRoute('put'),
-      deleteAlias: makeAddAliasRoute('delete'),
-      getUnchecked: router.get,
-      postUnchecked: router.post,
-      putUnchecked: router.put,
-      deleteUnchecked: router.delete,
+      getUnchecked: makeAddUncheckedRoute('get'),
+      postUnchecked: makeAddUncheckedRoute('post'),
+      putUnchecked: makeAddUncheckedRoute('put'),
+      deleteUnchecked: makeAddUncheckedRoute('delete'),
+      use: (middleware: UncheckedRequestHandler) => {
+        routerMiddleware.push(middleware);
+      },
     },
   );