Where is the render method of the AppPageRouteModule class called?

[R4R3D1FF]

Summary

In packages\next\src\server\route-modules\app-page\module.ts , the AppPageRouteModule class has a function called "render".
I was working on a bug and via logging, I confirmed that this function is being called, but I couldn't find any references to it via the VSCode typescript analyser, except for app-page.ts and edge-ssr.ts in templates, which I confirmed are not being called.

I'm guessing it is called via a build script or something, so can someone help me with where it might be?

Additional information

No response

Example

No response

[icyJoseph]

I can take a wild guess and say it is likely called within react, or rater react-dom's APIs.

Nope bad guess - I found also the templates app-page, etc, but you say that doesn't get hits when debugging? Are you debugging this is dev mode, build, start?

[R4R3D1FF]

im debugging in start

[icyJoseph]

Aha, ok I debugged it on dev without turbopack, and noticed that I had to put my debugger over at node_modules/next/dist/esm/build/templates/app-page.js

Screen.Recording.2025-08-05.at.13.54.36.mov

Screen.Recording.2025-08-05.at.13.54.55.mov

If I understand correctly, the template is copied over, which is why you might not be stopping there with some debugging techniques.

[Mr-Hulk-SMS]

You're correct that AppPageRouteModule's render() method isn’t directly referenced in app-page.ts or edge-ssr.ts. That’s because the call chain originates deeper in the Next.js internal routing and compilation pipeline.

Where it's actually triggered:

The render() method is called via the handle() method defined in the same module. Here's how it flows:

app-page.ts (in next/src/server/app-render/app-page.ts) imports AppPageRouteModule and instantiates it as part of the route handler setup.

The route handler is passed into Next's request handler pipeline, which in turn calls the handle() method on the route module.

Inside that handle() method, Next.js internally calls:

await this.render()

This is the point where your render() method is triggered — dynamically, based on the routing context.

Why you don’t see it statically in VS Code:
Because render() is dynamically referenced inside the class and not statically called from outside the module, the TypeScript analyzer (like in VS Code) won't show any external references to render().

Debug Tip:
If you want to trace execution, place a console.trace() or use a custom logger inside handle() — it’ll confirm that the call hits render() during requests handled via the app directory.

[R4R3D1FF]

This works, but then there are anonymous functions and it refers to the dist files

Trace:
at NextNodeServer.handleRequest (C:\Users\mausa\Documents\nextjs\packages\next\dist\server\base-server.js:469:17)
at NextNodeServer. (C:\Users\mausa\Documents\nextjs\packages\next\dist\server\next-server.js:985:39)
at C:\Users\mausa\Documents\nextjs\packages\next\dist\server\next.js:105:24
at process.processTicksAndRejections (node:internal/process/task_queues:105:5)

I guess I'll need to look at the next-server.ts file closely

[icyJoseph]

Yeah, and you'll end up at the points in the video above, roughly, and then enter the eventual routeModule.render.

[R4R3D1FF]

Yes, that's right, thank you