fix: add opt-in appendAutoPrefix for directory auto prefixes

README.md

@@ -127,6 +127,17 @@ fastify.register(autoLoad, {
 })
 ```
 
+### `appendAutoPrefix` (optional) - Default: `false`
+
+When `true`, `plugin.autoPrefix` is appended to the directory-derived prefix (from `dirNameRoutePrefix`) instead of replacing it.
+
+```js
+fastify.register(autoLoad, {
+  dir: path.join(__dirname, 'routes'),
+  appendAutoPrefix: true
+})
+```
+
 ### `matchFilter` (optional)
 
 Filter matching any path that should be loaded. Can be a RegExp, a string, or a function returning a boolean.
@@ -225,6 +236,8 @@ Any option specified here will override `plugin.autoConfig` options specified in
 
 When setting both `options.prefix` and `plugin.autoPrefix` they will be concatenated.
 
+By default, `plugin.autoPrefix` replaces directory-derived prefixes. Set `appendAutoPrefix: true` to keep directory prefixes and append `plugin.autoPrefix` after them.
+
 ```js
 // index.js
 fastify.register(autoLoad, {
@@ -409,6 +422,8 @@ autoConfig.prefix = '/hello'
 
 Set routing prefix for plugin.
 
+`plugin.autoPrefix` overrides directory-derived prefixes by default. Use the global `appendAutoPrefix` option to append `plugin.autoPrefix` to directory prefixes instead.
+
 ```js
 module.exports = function (fastify, opts, next) {
   fastify.get('/', (request, reply) => {

index.js

@@ -11,7 +11,8 @@ const defaults = {
   indexPattern: /^index(?:\.ts|\.js|\.cjs|\.mjs|\.cts|\.mts)$/iu,
   autoHooksPattern: /^[_.]?auto_?hooks(?:\.ts|\.js|\.cjs|\.mjs|\.cts|\.mts)$/iu,
   dirNameRoutePrefix: true,
-  encapsulate: true
+  encapsulate: true,
+  appendAutoPrefix: false
 }
 
 const fastifyAutoload = async function autoload (fastify, options) {
@@ -101,7 +102,7 @@ async function loadPlugin ({ file, type, directoryPrefix, options, log }) {
     plugin.autoConfig = undefined
   }
 
-  handlePrefixConfig({ plugin, pluginOptions, content, directoryPrefix })
+  handlePrefixConfig({ plugin, pluginOptions, content, directoryPrefix, appendAutoPrefix: options.appendAutoPrefix })
 
   return {
     plugin,
@@ -258,16 +259,18 @@ function loadPluginOptions (content, overrideConfig) {
   return { ...pluginConfig, ...overrideConfig }
 }
 
-function handlePrefixConfig ({ plugin, pluginOptions, content, directoryPrefix }) {
+function handlePrefixConfig ({ plugin, pluginOptions, content, directoryPrefix, appendAutoPrefix }) {
   if (pluginOptions.prefix?.endsWith('/')) {
     pluginOptions.prefix = pluginOptions.prefix.slice(0, -1)
   }
 
+  const autoPrefix = plugin.autoPrefix ?? content.autoPrefix
+
   let prefix
-  if (plugin.autoPrefix !== undefined) {
-    prefix = plugin.autoPrefix
-  } else if (content.autoPrefix !== undefined) {
-    prefix = content.autoPrefix
+  if (appendAutoPrefix && autoPrefix !== undefined && directoryPrefix) {
+    prefix = `${directoryPrefix}/${autoPrefix}`
+  } else if (autoPrefix !== undefined) {
+    prefix = autoPrefix
   } else {
     prefix = directoryPrefix
   }

test/issues/205/routes/children/new-routes.js

@@ -0,0 +1,7 @@
+'use strict'
+
+module.exports = async function (app) {
+  app.get('/entity', async () => ({ ok: true }))
+}
+
+module.exports.autoPrefix = '/batch'

test/issues/205/test.js

@@ -0,0 +1,60 @@
+'use strict'
+
+const { after, before, describe, it } = require('node:test')
+const assert = require('node:assert')
+const path = require('node:path')
+const Fastify = require('fastify')
+const autoLoad = require('../../../')
+
+describe('Issue 205: append autoPrefix to directory prefixes without breaking defaults', function () {
+  describe('default behavior', function () {
+    const app = Fastify()
+
+    before(async function () {
+      app.register(autoLoad, {
+        dir: path.join(__dirname, 'routes'),
+        options: { prefix: '/hooked-plugin' }
+      })
+      await app.ready()
+    })
+
+    after(async function () {
+      await app.close()
+    })
+
+    it('keeps autoPrefix overriding directory prefixes by default', async function () {
+      const overridden = await app.inject({ method: 'GET', url: '/hooked-plugin/batch/entity' })
+      assert.strictEqual(overridden.statusCode, 200)
+      assert.deepStrictEqual(overridden.json(), { ok: true })
+
+      const appended = await app.inject({ method: 'GET', url: '/hooked-plugin/children/batch/entity' })
+      assert.strictEqual(appended.statusCode, 404)
+    })
+  })
+
+  describe('appendAutoPrefix: true', function () {
+    const app = Fastify()
+
+    before(async function () {
+      app.register(autoLoad, {
+        dir: path.join(__dirname, 'routes'),
+        options: { prefix: '/hooked-plugin' },
+        appendAutoPrefix: true
+      })
+      await app.ready()
+    })
+
+    after(async function () {
+      await app.close()
+    })
+
+    it('concatenates directory prefixes before plugin autoPrefix', async function () {
+      const appended = await app.inject({ method: 'GET', url: '/hooked-plugin/children/batch/entity' })
+      assert.strictEqual(appended.statusCode, 200)
+      assert.deepStrictEqual(appended.json(), { ok: true })
+
+      const overridden = await app.inject({ method: 'GET', url: '/hooked-plugin/batch/entity' })
+      assert.strictEqual(overridden.statusCode, 404)
+    })
+  })
+})

types/index.d.ts

@@ -9,6 +9,7 @@ declare namespace fastifyAutoload {
   export interface AutoloadPluginOptions {
     dir: string
     dirNameRoutePrefix?: boolean | RewritePrefix
+    appendAutoPrefix?: boolean
     ignoreFilter?: Filter
     matchFilter?: Filter
     ignorePattern?: RegExp