optimize db usage in tagged object list

diff --git a/src/api/handlers.py b/src/api/handlers.py
index 01430cb..827cd7c 100644 (file)
--- a/src/api/handlers.py
+++ b/src/api/handlers.py
@@ -6,7 +6,6 @@ import json
 
 from django.contrib.sites.models import Site
 from django.core.urlresolvers import reverse
-from django.db.models import Prefetch
 from django.utils.functional import lazy
 from piston.handler import AnonymousBaseHandler, BaseHandler
 from piston.utils import rc
@@ -14,7 +13,7 @@ from sorl.thumbnail import default
 
 from catalogue.forms import BookImportForm
 from catalogue.models import Book, Tag, BookMedia, Fragment, Collection
-from catalogue.models.tag import TagRelation
+from catalogue.models.tag import prefetch_relations
 from picture.models import Picture
 from picture.forms import PictureImportForm
 
@@ -210,13 +209,7 @@ class AnonymousBooksHandler(AnonymousBaseHandler, BookDetails):
 
         books = books.only('slug', 'title', 'cover', 'cover_thumb')
         for category in book_tag_categories:
-            books = books.prefetch_related(
-                Prefetch(
-                    'tag_relations',
-                    queryset=TagRelation.objects.filter(tag__category=category)
-                        .select_related('tag').only('tag__name_pl', 'object_id'),
-                    to_attr='%s_relations' % category))
-
+            books = prefetch_relations(books, category)
         if books:
             return books
         else:
@@ -260,9 +253,7 @@ def _tags_getter(category):
 def _tag_getter(category):
     @classmethod
     def get_tag(cls, book):
-        if hasattr(book, '%s_relations' % category):
-            return ', '.join(rel.tag.name for rel in getattr(book, '%s_relations' % category))
-        return ', '.join(book.tags.filter(category=category).values_list('name', flat=True))
+        return book.tag_unicode(category)
     return get_tag
 
 

diff --git a/src/catalogue/models/book.py b/src/catalogue/models/book.py
index 0ed9716..5ac999e 100644 (file)
--- a/src/catalogue/models/book.py
+++ b/src/catalogue/models/book.py
@@ -22,6 +22,7 @@ from catalogue import constants
 from catalogue.fields import EbookField
 from catalogue.models import Tag, Fragment, BookMedia
 from catalogue.utils import create_zip, gallery_url, gallery_path
+from catalogue.models.tag import prefetched_relations
 from catalogue import app_settings
 from catalogue import tasks
 from wolnelektury.utils import makedirs
@@ -109,8 +110,15 @@ class Book(models.Model):
     def authors(self):
         return self.tags.filter(category='author')
 
+    def tag_unicode(self, category):
+        relations = prefetched_relations(self, category)
+        if relations:
+            return ', '.join(rel.tag.name for rel in relations)
+        else:
+            return ', '.join(self.tags.filter(category=category).values_list('name', flat=True))
+
     def author_unicode(self):
-        return ", ".join(self.authors().values_list('name', flat=True))
+        return self.tag_unicode('author')
 
     def save(self, force_insert=False, force_update=False, **kwargs):
         from sortify import sortify

diff --git a/src/catalogue/models/tag.py b/src/catalogue/models/tag.py
index 1531973..00bdcb5 100644 (file)
--- a/src/catalogue/models/tag.py
+++ b/src/catalogue/models/tag.py
@@ -7,6 +7,7 @@ from django.core.cache import caches
 from django.contrib.auth.models import User
 from django.db import models
 from django.db.models import permalink
+from django.db.models.query import Prefetch
 from django.dispatch import Signal
 from django.utils.translation import ugettext_lazy as _
 
@@ -246,3 +247,18 @@ class Tag(TagBase):
 
 # Pickle complains about not having this.
 TagRelation = Tag.intermediary_table_model
+
+
+def prefetch_relations(objects, category, only_name=True):
+    queryset = TagRelation.objects.filter(tag__category=category).select_related('tag')
+    if only_name:
+        queryset = queryset.only('tag__name_pl', 'object_id')
+    return objects.prefetch_related(
+        Prefetch('tag_relations', queryset=queryset, to_attr='%s_relations' % category))
+
+
+def prefetched_relations(obj, category):
+    if hasattr(obj, '%s_relations' % category):
+        return getattr(obj, '%s_relations' % category)
+    else:
+        return None

diff --git a/src/catalogue/templatetags/catalogue_tags.py b/src/catalogue/templatetags/catalogue_tags.py
index 6f50ad7..c02a5d7 100644 (file)
--- a/src/catalogue/templatetags/catalogue_tags.py
+++ b/src/catalogue/templatetags/catalogue_tags.py
@@ -325,6 +325,7 @@ def tag_list(tags, choices=None, category=None, list_type='books'):
         other = other.filter(items__content_type=ct).distinct()
         if list_type == 'audiobooks':
             other = other.filter(id__in=get_audiobook_tags())
+        other = other.only('name', 'slug', 'category')
     else:
         other = []
 

diff --git a/src/catalogue/utils.py b/src/catalogue/utils.py
index e94c67d..60a5671 100644 (file)
--- a/src/catalogue/utils.py
+++ b/src/catalogue/utils.py
@@ -2,24 +2,24 @@
 # This file is part of Wolnelektury, licensed under GNU Affero GPLv3 or later.
 # Copyright © Fundacja Nowoczesna Polska. See NOTICE for more information.
 #
-from collections import defaultdict
 import hashlib
 import os.path
 import random
 import re
 import time
 from base64 import urlsafe_b64encode
-
-from django.http import HttpResponse
-from django.core.files.uploadedfile import UploadedFile
-from django.core.files.storage import DefaultStorage
-from django.utils.encoding import force_unicode
-from django.conf import settings
-from os import mkdir, path, unlink
+from collections import defaultdict
 from errno import EEXIST, ENOENT
 from fcntl import flock, LOCK_EX
+from os import mkdir, path, unlink
 from zipfile import ZipFile
 
+from django.conf import settings
+from django.core.files.storage import DefaultStorage
+from django.core.files.uploadedfile import UploadedFile
+from django.http import HttpResponse
+from django.utils.encoding import force_unicode
+
 from reporting.utils import read_chunks
 
 # Use the system (hardware-based) random number generator if it exists.

diff --git a/src/catalogue/views.py b/src/catalogue/views.py
index 2aa98f7..6782e53 100644 (file)
--- a/src/catalogue/views.py
+++ b/src/catalogue/views.py
@@ -12,7 +12,7 @@ from django.template.loader import render_to_string
 from django.shortcuts import render_to_response, get_object_or_404, render, redirect
 from django.http import HttpResponse, HttpResponseRedirect, Http404, HttpResponsePermanentRedirect, JsonResponse
 from django.core.urlresolvers import reverse
-from django.db.models import Q
+from django.db.models import Q, QuerySet
 from django.contrib.auth.decorators import login_required, user_passes_test
 from django.utils.http import urlquote_plus
 from django.utils import translation
@@ -29,6 +29,7 @@ from catalogue import forms
 from catalogue.helpers import get_top_level_related_tags
 from catalogue.models import Book, Collection, Tag, Fragment
 from catalogue.utils import split_tags
+from catalogue.models.tag import prefetch_relations
 
 staff_required = user_passes_test(lambda user: user.is_staff)
 
@@ -103,7 +104,10 @@ def object_list(request, objects, fragments=None, related_tags=None, tags=None,
             else:
                 fragments = Fragment.objects.filter(book__in=objects)
         related_tag_lists.append(
-            Tag.objects.usage_for_queryset(fragments, counts=True).filter(category='theme').exclude(pk__in=tag_ids))
+            Tag.objects.usage_for_queryset(fragments, counts=True).filter(category='theme').exclude(pk__in=tag_ids)
+            .only('name', 'sort_key', 'category', 'slug'))
+        if isinstance(objects, QuerySet):
+            objects = prefetch_relations(objects, 'author')
 
     categories = split_tags(*related_tag_lists)
 

diff --git a/src/picture/models.py b/src/picture/models.py
index e10d2fa..6d8def3 100644 (file)
--- a/src/picture/models.py
+++ b/src/picture/models.py
@@ -12,6 +12,8 @@ from django.core.files.storage import FileSystemStorage
 from django.utils.datastructures import SortedDict
 from fnpdjango.utils.text.slughifi import slughifi
 from ssify import flush_ssi_includes
+
+from catalogue.models.tag import prefetched_relations
 from picture import tasks
 from StringIO import StringIO
 import jsonfield
@@ -128,7 +130,11 @@ class Picture(models.Model):
         return self.tags.filter(category='author')
 
     def tag_unicode(self, category):
-        return ", ".join(self.tags.filter(category=category).values_list('name', flat=True))
+        relations = prefetched_relations(self, category)
+        if relations:
+            return ', '.join(rel.tag.name for rel in relations)
+        else:
+            return ', '.join(self.tags.filter(category=category).values_list('name', flat=True))
 
     def author_unicode(self):
         return self.tag_unicode('author')