Denormalize from_url_without_rest onto the redirects model

readthedocs/redirects/admin.py

@@ -17,6 +17,7 @@ class RedirectAdmin(admin.ModelAdmin):
         'from_url',
         'to_url',
     )
+    readonly_fields = ('from_url_without_rest',)
 
 
 admin.site.register(Redirect, RedirectAdmin)

readthedocs/redirects/migrations/0004_denormalize-from-url.py

@@ -0,0 +1,38 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.26 on 2020-03-14 14:15
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+def forward(apps, schema_editor):
+    """Calculate new ``from_url_without_rest`` attribute."""
+    Redirect = apps.get_model('redirects', 'Redirect')
+
+    queryset = Redirect.objects.filter(
+        redirect_type='exact',
+        from_url__endswith='$rest',
+    )
+    for redirect in queryset:
+        redirect.from_url_without_rest = redirect.from_url.replace('$rest', '') or None
+        redirect.save()
+
+def backward(apps, schema_editor):
+    # just no-op
+    pass
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('redirects', '0003_add_default_redirect_http_status_to_302'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='redirect',
+            name='from_url_without_rest',
+            field=models.CharField(blank=True, db_index=True, help_text='Only for internal querying use', max_length=255, null=True),
+        ),
+        migrations.RunPython(forward, backward),
+    ]

readthedocs/redirects/models.py

@@ -77,6 +77,16 @@ class Redirect(models.Model):
         blank=True,
     )
 
+    # We are denormalizing the database here to easily query for Exact Redirects
+    # with ``$rest`` on them from El Proxito
+    from_url_without_rest = models.CharField(
+        max_length=255,
+        db_index=True,
+        help_text='Only for internal querying use',
+        blank=True,
+        null=True,
+    )
+
     to_url = models.CharField(
         _('To URL'),
         max_length=255,
@@ -102,6 +112,11 @@ class Meta:
         verbose_name_plural = _('redirects')
         ordering = ('-update_dt',)
 
+    def save(self, *args, **kwargs):  # pylint: disable=arguments-differ
+        if self.redirect_type == 'exact' and '$rest' in self.from_url:
+            self.from_url_without_rest = self.from_url.replace('$rest', '')
+        super().save(*args, **kwargs)
+
     def __str__(self):
         redirect_text = '{type}: {from_to_url}'
         if self.redirect_type in ['prefix', 'page', 'exact']:

readthedocs/redirects/querysets.py

@@ -1,9 +1,14 @@
 """Queryset for the redirects app."""
 
+import logging
+
 from django.db import models
+from django.db.models import Value, CharField, Q, F
 
 from readthedocs.core.utils.extend import SettingsOverrideObject
 
+log = logging.getLogger(__name__)
+
 
 class RedirectQuerySetBase(models.QuerySet):
 
@@ -25,7 +30,56 @@ def api(self, user=None, detail=True):
         return queryset
 
     def get_redirect_path_with_status(self, path, full_path=None, language=None, version_slug=None):
-        for redirect in self.select_related('project'):
+        # add extra fields with the ``path`` and ``full_path`` to perform a
+        # filter at db level instead with Python
+        queryset = self.annotate(
+            path=Value(
+                path,
+                output_field=CharField(),
+            ),
+            full_path=Value(
+                full_path,
+                output_field=CharField(),
+            ),
+        )
+        prefix = Q(
+            redirect_type='prefix',
+            path__startswith=F('from_url'),
+        )
+        page = Q(
+            redirect_type='page',
+            path__exact=F('from_url'),
+        )
+        exact = (
+            Q(
+                redirect_type='exact',
+                from_url__endswith='$rest',
+                full_path__startswith=F('from_url_without_rest'),
+            ) | Q(
+                redirect_type='exact',
+                full_path__exact=F('from_url'),
+            )
+        )
+        sphinx_html = (
+            Q(
+                redirect_type='sphinx_html',
+                path__endswith='/',
+            ) | Q(
+                redirect_type='sphinx_html',
+                path__endswith='/index.html',
+            )
+        )
+        sphinx_htmldir = Q(
+            redirect_type='sphinx_htmldir',
+            path__endswith='.html',
+        )
+
+        queryset = queryset.filter(prefix | page | exact | sphinx_html | sphinx_htmldir)
+
+        # There should be one and only one redirect returned by this query. I
+        # can't think in a case where there can be more at this point. I'm
+        # leaving the loop just in case for now
+        for redirect in queryset.select_related('project'):
             new_path = redirect.get_redirect_path(
                 path=path,
                 language=language,