Fastify 5.8.2 and autohooks produces "route already declared" error

[mccare]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Fastify version

4.27.0

Plugin version

5.8.2

Node.js version

20.13.1

Operating system

macOS

Operating system version (i.e. 20.04, 11.3, 10)

14.5

Description

When going from 5.8.0 to 5.8.2 my code base will throw a FastifyError [Error]: Method 'GET' already declared for route '/backend' error about having a duplicate route. I managed to reproduce this and added a simple repository to show the error.

Link to code that reproduces the bug

https://github.com/mccare/fastify-autoload-hook

Expected Behavior

It should just register the route into /backend/example (in this case) and not try to register under /backend

[mcollina]

@climba03003 wdyt? This might have been broken by #375?

[climba03003]

I am more incline to believe it broken by #368

fastify-autoload/index.js

Lines 87 to 89 in 64e6bf2

	fastify.register(composedPlugin, {
	prefix: options.options?.prefix ?? replaceRouteParamPattern(prefix)
	})

The problem exist when you provide a prefix in options, then it is always precedent (no matter it is nested or not).
Removing options.options?.prefix ?? should helps?

[climba03003]

After double check the document, I can see it as intended behavior.
When options.prefix is provided, it is used for all routes found.
That means all the routes plugin is prefixed by the same prefix.

Providing same / route inside should throw an Error.
I don't knows why it works in previous version, maybe different combination of options provide different behavior (wrong behavior).

[mccare]

So adding the prefix will just add the '/backend' to every route right? But the directory would still be appended to the prefix, so in the example:

• GET /backend
• GET /backend/example

Where is the "duplicate route" error coming from then? Or other way to ask: what would I have to configure so that every route will have a fixed prefix?

I guess I could just get rid of the autohooks.js and make a plugin out of it, since without the autohook it will work as expected. (or as it worked previously)

[climba03003]

So adding the prefix will just add the '/backend' to every route right?

No, from the document is that all routes will use the prefix and it will not respect the directory structure.
That is the reason why my PR unit test failed.

This happen only when you don't use autoHooks which means autoHooks is overrided the behavior or is being wrong in the beginning.

When you are providing options.prefix, you must use autoPrefix to append the path. That is what I can read from the unit test and document.

[climba03003]

I think we should decide which behavior is the correct one.
To me, it should be appending to the prefix.

But you can see it is very weird in the test below. It ignore the folder child.

fastify-autoload/test/issues/326/autohooks/index.js

Lines 13 to 18 in c1685f4

	fastify.register(autoLoad, {
	dir: path.join(__dirname, '/routes-b'),
	autoHooks: true,
	cascadeHooks: true,
	options: { prefix: 'custom-prefix' }
	})

fastify-autoload/test/issues/326/test.js

Lines 64 to 79 in c1685f4

	app.inject({
	url: '/custom-prefix'
	}, function (err, res) {
	t.error(err)
	t.equal(res.statusCode, 200)
	})
	app.inject({
	url: '/custom-prefix/not-exists'
	}, function (err, res) {
	t.error(err)
	t.equal(res.headers.from, 'routes-b')
	t.equal(res.statusCode, 404)
	})

cc @fastify/core

[jsumners]

@climba03003 can you summarize what question you are asking core?

[climba03003]

can you summarize what question you are asking core?

The current options.prefix is not clear enough what is the expected behavior.
It can be passed to all found routes with that prefix but NOT extends the directory name.
or
It can be passed to all found routes with that prefix AND extends the directory name.

I prefer the latter.

[jsumners]

I really don't have an opinion. I have not used this module.

[mccare]

The current options.prefix is not clear enough what is the expected behavior. It can be passed to all found routes with that prefix but NOT extends the directory name. or It can be passed to all found routes with that prefix AND extends the directory name.

The latter is how it is working in 5.8.0 and before, and I think it makes more sense, too. I use the prefix to have a prefix for all routes e.g. when sharing a hostname with other services and routing is then done by URL prefix.

[mccare]

For me, just removing the autohooks.js fixed my problem. I can live with the missing encapsulation for now. Feel free to close.

[paul-norman]

I've hit this problem too, it broke my system when moving from 5.8.0 to 5.8.1. I've reverted to 5.8.0 for the time being.

I'm using it in what seemed like a logical manner to me:

fastify.register(AutoLoad, {
    dir:          'routes/api',
    options:      { prefix: '/api' },
    autoHooks:    true,
    cascadeHooks: true
});

and then a routes/api folder structure similar to:

• routes.js (containing: / and /test)
• autohooks.js
• [subfolder1]
  • routes.js (containing: / and /sub1test)
  • autohooks.js
• [subfolder2]
  • routes.js (containing: / and /sub2test)
  • autohooks.js

I would expect the following routes to exist:

// Using autohooks from "routes/api"
/api/
/api/test

// Using autohooks from "routes/api" and "routes/api/subfolder1"
/api/subfolder1/
/api/subfolder1/sub1test

// Using autohooks from "routes/api" and "routes/api/subfolder2"
/api/subfolder2/
/api/subfolder2/sub2test

If this will not be the case going forward, how do I achieve this goal in the newer versions?