Handle release notes for releases without release notes

If a release is made without release notes (could happen when a release
is withdrawn before made public), we would list it under release notes
and then generate a 404 when trying to view it.

For now, 18.5 is the only such release, bur make the code generic to
cover potential future cases. So for now, we put the list of versions
hardcoded in the views.py file. If this happens repeatedly, we'll
probalby want to move it to a better place.

Author: mhagander

pgweb/docs/views.py

@@ -7,6 +7,7 @@
 from django.conf import settings
 
 from decimal import Decimal, ROUND_DOWN
+import itertools
 import os
 import re
 
@@ -293,14 +294,19 @@ def manualarchive(request):
 ]
 release_notes_only_versions = [{'major': major, 'minor': minor} for major, minor in _release_notes_only_versions]
 
+no_release_notes_versions = [
+    {"major": 18, "minor": 5},
+]
+no_release_notes_per_major = dict((k, list(m['minor'] for m in v)) for k, v in itertools.groupby(no_release_notes_versions, key=lambda x: x['major']))
+
 
 def release_notes_list(request):
     """Lists the available release notes"""
     # We only keep 6.3 and newer in core_version (for legacy reasons)
     releases = exec_to_dict("SELECT tree AS major, minor FROM core_version INNER JOIN generate_series(0, latestminor) g(minor) ON true WHERE testing=0 AND tree > 6.2 ORDER BY tree DESC, minor DESC")
 
     r = render_pgweb(request, 'docs', 'docs/release_notes_list.html', {
-        'releases': releases + release_notes_only_versions,
+        'releases': [v for v in releases + release_notes_only_versions if v not in no_release_notes_versions],
     })
     r['xkey'] = 'pgdocs_all'
     return r
@@ -328,6 +334,10 @@ def release_notes(request, version):
         minor_version = Decimal(version_pieces[1])
         if int(version_pieces[0]) >= 10 or int(version_pieces[0]) <= 1:
             if major_version > 1:
+                if {"major": major_version, "minor": minor_version} in no_release_notes_versions:
+                    # Redirect to the following version if this one has no release notes. In the very unlikely event we have more than one
+                    # such version, we'll just redirect more than once.
+                    return HttpResponseRedirect("/docs/release/{}.{}/".format(major_version, minor_version + 1))
                 if minor_version == 0:
                     version_file = 'release-{}.html'.format(major_version)
                 else:
@@ -366,6 +376,9 @@ def release_notes(request, version):
         available_minor_versions = exec_to_dict("SELECT minor FROM generate_series(0, (SELECT latestminor FROM core_version WHERE tree=%(major_version)s)) g(minor) ORDER BY minor DESC", {
             'major_version': major_version,
         })
+        if major_version in no_release_notes_per_major:
+            available_minor_versions = [v for v in available_minor_versions if v['minor'] not in no_release_notes_per_major[major_version]]
+        print(available_minor_versions)
         previous_minor = minor_version - 1 if minor_version > 0 else None
         next_minor = minor_version + 1 if minor_version < available_minor_versions[0]['minor'] else None
     else: