8 Commits

3 changed files with 92 additions and 7 deletions

View File

@@ -3,4 +3,77 @@ This repository holds the django library that StarFields uses for the django-res
# Differences with the DRF generic views
It changes the generic lifecycles of all the CRUD operations to fit within them automated caching functionality. Caching and deleting cache keys is handled by the library in a way that the cache keys have no duplicates. The generic views offered include single item CRUD and list-based CRUD.
To manage automated caching this the library replaces (and appends to) the DRF filters. These filters need a get_unique_dict method in order to avoid the duplicate cache keys problem.
# Usage
### Ensure that the module is in the INSTALLED_APPS in settings.py:
```python
INSTALLED_APPS = [
...
'starfields_drf_generics',
]
```
### Making views in views.py:
```python
from starfields_drf_generics import generics
from starfields_drf_generics import filters as libfilters
class CategoriesView(generics.CachedListRetrieveAPIView):
"""
This view lists all the categories. Usually this API is called on the shop initialization and the result is saved on the front-end for use shop-wide.
"""
cache_prefix = "shop.products.categories"
cache_vary_on_user = False
cache_timeout_mins = ShopSettings.get_solo().cache_timeout
queryset = Category.objects.all()
serializer_class = CategorySerializer
paged = False
filter_backends = []
logger = logger
cache = cache
class SearchView(generics.CachedListRetrieveAPIView):
"""
This view lists the gallery pictures with extensive searching and filtering features. You can use this API to get the latest pictures, perform picture searches among others.
"""
cache_prefix = "gallery.search"
cache_vary_on_user = False
cache_timeout_mins = GallerySettings.get_solo().cache_timeout
queryset = Picture.objects.filter(published=True)
serializer_class = PictureSerializer
ordering_fields = ('similarity','date_added','updated')
category_class = Category
search_fields = ['name','slug','tag__name','tag__slug']
paged = True
default_page_size = 20
filter_backends = (libfilters.CategoryFilter,
libfilters.TrigramSearchFilter,
libfilters.OrderingFilter,
)
logger = logger
cache = cache
```
### New class attributes that are used
```python
cache_prefix = defines the prefix that the module will use when saving values in the cache
cache_vary_on_user = defines whether keys saved in the cache are different for each user, in which case extra user information will be added to the cache prefix
cache_timeout_mins = the cache key timeout
filter_backends = the filters that you want the view to have, each can be configured with view class attributes
ordering_fields = if you use the OrderingFilter you must indicate what fields the user can order by, the first element is used as the default order
search_fields = if you use the TrigramSearchFilter you must indicate the fields to search through
paged = your generic view can have a pager for the user to choose pages or it can be a full listing
default_page_size = the default size of the pages if a user has not indicated a page size
logger = you should register a logger in order to get error feedback in your deployments
cache = the main feature of this module is automated and organized caching, you should register your cache here
```
### Extras
The source code is similar to the django-rest-framework's generic classes and related objects, it should be eminently readable. As with the rest framework's generics multiple inheritance is used through mixing to organize the behavior of each class in a standalone setting.
# Duplicate Cache Keys Problem
The problem arises in the way cache keys are created, the naive method is to just use the information from the url of the request and just save it to the cache. This creates a problem in that a request such as https://example.com/api/v1/pictures/search?search=mypic&category=mycat and a request https://example.com/api/v1/pictures/search?category=mycat&search=mypic contain the same information in their cache values. So the order of each filter or the order within the filters (such as the facet filter I made for e-commerce APIs) affects the caching behavior and creates more work for our APIs.
The way this module fixes the duplicate cache keys problem is by systematically ordering the filters through each filter's get_unique_dict method that are called in cache_mixins.py and then running the sorted_params_string utility function in the resulting dict.

View File

@@ -20,3 +20,9 @@ classifiers = [
[project.urls]
"Homepage" = "https://git.vickys-corner.xyz/ace/starfields-drf-generics"
[options.packages.find]
where = starfields_drf_generics
[options.package_data]
templates.filters =
*.html

View File

@@ -2,7 +2,6 @@ from django_filters import rest_framework as filters
from django.contrib.postgres.search import TrigramSimilarity
from django.db.models.functions import Concat
from django.db.models import CharField
from shop.models.product import Product, Facet
from rest_framework.filters import BaseFilterBackend
import operator
from django.template import loader
@@ -89,7 +88,7 @@ class CategoryFilter(BaseFilterBackend):
"""
This filter assigns the view.category object for later use, in particular for filters that depend on this one.
"""
template = 'starfields_drf_generics/filters/categories.html'
template = 'starfields_drf_generics/templates/filters/categories.html'
category_field = 'category'
def get_category_class(self, view, request):
@@ -203,7 +202,7 @@ class FacetFilter(BaseFilterBackend):
"""
This filter requires CategoryFilter to be ran before it. It assigns the view.facets which includes all the facets applicable to the current category.
"""
template = 'starfields_drf_generics/filters/facets.html'
template = 'starfields_drf_generics/templates/filters/facets.html'
def get_facet_class(self, view, request):
return getattr(view, 'facet_class', None)
@@ -216,13 +215,20 @@ class FacetFilter(BaseFilterBackend):
def assign_view_facets(self, request, view):
if not hasattr(view, 'facets'):
if hasattr(view, 'facet_class'):
self.facet_class = self.get_facet_class(view, request)
assert self.facet_class is not None, (
f"{view.__class__.__name__} should include a `facet_class` attribute"
)
if view.category:
if view.category.tn_ancestors_pks:
view.facets = Facet.objects.filter(Q(category__id=view.category.id) | Q(category__id__in=view.category.tn_ancestors_pks.split(','))).prefetch_related('facet_tags')
view.facets = self.facet_class.objects.filter(Q(category__id=view.category.id) | Q(category__id__in=view.category.tn_ancestors_pks.split(','))).prefetch_related('facet_tags')
else:
view.facets = Facet.objects.filter(category__id=view.category.id).prefetch_related('facet_tags')
view.facets = self.facet_class.objects.filter(category__id=view.category.id).prefetch_related('facet_tags')
else:
view.facets = Facet.objects.filter(category__tn_level=1).prefetch_related('facet_tags')
view.facets = self.facet_class.objects.filter(category__tn_level=1).prefetch_related('facet_tags')
def get_filters_dict(self, request, view):
"""
@@ -423,7 +429,7 @@ class TrigramSearchFilter(BaseFilterBackend):
# TODO misunderstood the urlconf stuff of the RUD methods, this is probably unnecessary
class SlugSearchFilter(BaseFilterBackend):
# The URL query parameter used for the search.
template = 'starfields_drf_generics/filters/slug.html'
template = 'starfields_drf_generics/templates/filters/slug.html'
slug_title = _('Slug Search')
slug_description = _("The instance's slug.")
slug_field = 'slug'