[FIX] website: redirect to case insensitive URL if not exact match

Before this commit, if a link to a page was not correct because of a
case mismatch, it would simply land on a 404 page.
While it's correct, as URL are case sensitive, it leads to a few bad UX
flow at the admin/editor level:
- Create a link in your page (on a text or a button eg), type an URL
  which does not exists (to create it after) like /Page
- Click on the link/button you just made, you are redirected to /Page
  which display a 404 with the "Create page" option (correct)
- When you click on that button, it will actually create a page with
  /page URL, leading to a mismatch between the URL you created and the
  page URL.
  Your link/button will still lead to a 404 URL as it points to /Page.

Since it's just a fallback when an exact URL match is not found, it
should not break anything and should not have bad impact at any level
(seo/speed etc).
Indeed:
- It's done through a 302 redirect
- `_serve_page()` is already a fallback case, so it will only make
  the `website.redirect` and 404 cases a bit slower due to the extra
  search query.

The only possible scenario seems to be if the user (mind the uppercase):
- Created a /Page page
- Created a redirect from /page to /another-page

In this case, /page won't land on /another-page but on /Page.
This flow seems unlikely and is not actually wrong either way.
At least, it certainly is less important than ensuring a case
insensitive fallback.

Finally, note that another solution would have been to either:
- Force page URL to lower case.
  -> This is not stable friendly, people might be relying on this to
     create pages with different casing:
     `/Batman-VII-The-Dark-Knight-Whatevers`, while not recommended,
     doesn't sounds idiot.
     On top of not being stable friendly, we probably want to keep
     offering this possibility
- Redirect all URLs to lowercase endpoints.
  -> This is obviously not stable and not Odoo's jobs. It should be
     something decided by the sysadmin and done at nginx (etc) level.

task-3110294
opw-3104030

closes odoo#109812

Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/website/models/ir_http.py

@@ -247,13 +247,22 @@ def _get_translation_frontend_modules_name(cls):
     @classmethod
     def _serve_page(cls):
         req_page = request.httprequest.path
-        page_domain = [('url', '=', req_page)] + request.website.website_domain()
 
-        published_domain = page_domain
+        def _search_page(comparator='='):
+            page_domain = [('url', comparator, req_page)] + request.website.website_domain()
+            return request.env['website.page'].sudo().search(page_domain, order='website_id asc', limit=1)
+
         # specific page first
-        page = request.env['website.page'].sudo().search(published_domain, order='website_id asc', limit=1)
+        page = _search_page()
+
+        # case insensitive search
+        if not page:
+            page = _search_page('=ilike')
+            if page:
+                logger.info("Page %r not found, redirecting to existing page %r", req_page, page.url)
+                return request.redirect(page.url)
 
-        # redirect withtout trailing /
+        # redirect without trailing /
         if not page and req_page != "/" and req_page.endswith("/"):
             return request.redirect(req_page[:-1])
 

addons/website/tests/test_page.py

@@ -271,3 +271,10 @@ def test_homepage_not_slash_url(self):
         root_html = html.fromstring(r.content)
         canonical_url = root_html.xpath('//link[@rel="canonical"]')[0].attrib['href']
         self.assertEqual(canonical_url, website.domain + "/")
+
+    def test_page_url_case_insensitive_match(self):
+        r = self.url_open('/page_1')
+        self.assertEqual(r.status_code, 200, "Reaching page URL, common case")
+        r2 = self.url_open('/Page_1', allow_redirects=False)
+        self.assertEqual(r2.status_code, 302, "URL exists only in different casing, should redirect to it")
+        self.assertTrue(r2.headers.get('Location').endswith('/page_1'), "Should redirect /Page_1 to /page_1")