add wrapper for API routes

Author: lobsterkatie

packages/nextjs/src/config/wrappers/index.ts

@@ -4,3 +4,4 @@ export { withSentryServerSideAppGetInitialProps } from './withSentryServerSideAp
 export { withSentryServerSideDocumentGetInitialProps } from './withSentryServerSideDocumentGetInitialProps';
 export { withSentryServerSideErrorGetInitialProps } from './withSentryServerSideErrorGetInitialProps';
 export { withSentryGetServerSideProps } from './withSentryGetServerSideProps';
+export { withSentryAPI } from './withSentryAPI';

packages/nextjs/src/config/wrappers/withSentryAPI.ts

@@ -0,0 +1,43 @@
+// We import these types from `withSentry` rather than directly from `next` because our version can work simultaneously
+// with multiple versions of next. See note in `withSentry` for more.
+import type { NextApiHandler, WrappedNextApiHandler } from '../../utils/withSentry';
+import { withSentry } from '../../utils/withSentry';
+
+/**
+ * TODO
+ */
+export function withSentryAPI(
+  maybeWrappedHandler: NextApiHandler | WrappedNextApiHandler,
+  parameterizedRoute: string,
+): WrappedNextApiHandler {
+  // We want the innards of `withSentry` to have access to the parameterized route, so it can be used when we start the
+  // request transaction. If we were always the ones calling `withSentry` (the way we're always the ones to call
+  // `withSentryServerSideProps`, for example), then we could just pass it in as a second parameter and know it would
+  // always be there. But in the case where users have already manually wrapped their API route handlers with
+  // `withSentry`, they're the ones calling it, without the parameterized route as a second parameter. We need a
+  // different way to make it available.
+  //
+  // Fortunately, with some clever `this` usage, we can do it.
+
+  // First we add it as a property on the exported handler.
+  maybeWrappedHandler.__sentry_route__ = parameterizedRoute;
+
+  // TODO: Finish explanation
+  // TODO: Figure out if `maybeWrappedHandler` is `withSentry` itself or the results of calling `withSentry` on the original handler
+
+  if ('__sentry_wrapped__' in maybeWrappedHandler) {
+    return wrapLite(maybeWrappedHandler);
+  }
+
+  return withSentry(maybeWrappedHandler);
+}
+
+// TODO: This needs a better name, and a docstring
+function wrapLite(alreadyWrappedHandler: WrappedNextApiHandler): WrappedNextApiHandler {
+  const newWrapper: WrappedNextApiHandler = (req, res) => {
+    // Make `alreadyWrappedHandler` its own `this`
+    return alreadyWrappedHandler.call(alreadyWrappedHandler, req, res);
+  };
+
+  return newWrapper;
+}

packages/nextjs/src/index.server.ts

@@ -134,6 +134,7 @@ export {
   withSentryServerSideAppGetInitialProps,
   withSentryServerSideDocumentGetInitialProps,
   withSentryServerSideErrorGetInitialProps,
+  withSentryAPI,
 } from './config/wrappers';
 export { withSentry } from './utils/withSentry';