news trigram search

apps/news/filters.py

@@ -1,6 +1,8 @@
 """Filters from application News"""
-from django_filters import rest_framework as filters
+from django.core.validators import EMPTY_VALUES
 from django.utils.translation import gettext_lazy as _
+from django_filters import rest_framework as filters
+from rest_framework.serializers import ValidationError
 
 from news import models
 
@@ -29,6 +31,7 @@ class NewsListFilterSet(filters.FilterSet):
         (SORT_BY_START_CHOICE, "start"),
     )
     sort_by = filters.ChoiceFilter(method='sort_by_field', choices=SORT_BY_CHOICES)
+    search = filters.CharFilter(method='search_news')
 
     class Meta:
         """Meta class"""
@@ -41,8 +44,16 @@ class NewsListFilterSet(filters.FilterSet):
             'tag_value__in',
             'state',
             'sort_by',
+            'search',
         )
 
+    def search_news(self, queryset, name, value):
+        if value not in EMPTY_VALUES:
+            if len(value) < 3:
+                raise ValidationError({'detail': _('Type at least 3 characters to search please.')})
+            return queryset.trigram_search(value)
+        return queryset
+
     def in_tags(self, queryset, name, value):
         tags = value.split('__')
         return queryset.filter(tags__value__in=tags)

apps/news/models.py

@@ -6,7 +6,9 @@ from django.contrib.contenttypes import fields as generic
 from django.contrib.contenttypes.models import ContentType
 from django.contrib.postgres.fields import HStoreField
 from django.db import models
-from django.db.models import Case, When
+from django.db.models import Case, When, Q, F
+from django.db.models.functions import Cast
+from django.contrib.postgres.search import TrigramSimilarity
 from django.urls.exceptions import NoReverseMatch
 from django.utils import timezone
 from django.utils.translation import gettext_lazy as _
@@ -144,6 +146,46 @@ class NewsQuerySet(TranslationQuerysetMixin):
     def by_locale(self, locale):
         return self.filter(title__icontains=locale)
 
+    def trigram_search(self, search_value: str):
+        """Search with mistakes by name or last name."""
+        return self.annotate(
+            description_str=Cast('description', models.TextField()),
+            title_str=Cast('title', models.TextField()),
+            subtitle_str=Cast('subtitle', models.TextField()),
+            search_contains_match=Case(
+                models.When(Q(description_str__icontains=search_value) | Q(title_str__icontains=search_value) | Q(
+                    subtitle_str__icontains=search_value), then=100),
+                default=0,
+                output_field=models.FloatField(),
+            ),
+            description_similarity=models.Case(
+                models.When(
+                    Q(description__isnull=False),
+                    then=TrigramSimilarity('description_str', search_value.lower()),
+                ),
+                default=0,
+                output_field=models.FloatField()
+            ),
+            title_similarity=models.Case(
+                models.When(
+                    Q(title__isnull=False),
+                    then=TrigramSimilarity('title_str', search_value.lower()),
+                ),
+                default=0,
+                output_field=models.FloatField()
+            ),
+            subtitle_similarity=models.Case(
+                models.When(
+                    Q(subtitle__isnull=False),
+                    then=TrigramSimilarity('subtitle_str', search_value.lower()),
+                ),
+                default=0,
+                output_field=models.FloatField()
+            ),
+            relevance=(F('search_contains_match') + F('description_similarity') + F('title_similarity') + F(
+                'subtitle_similarity'))
+        ).filter(relevance__gte=0.3).order_by('-relevance')
+
 
 class News(GalleryMixin, BaseAttributes, TranslatedFieldsMixin, HasTagsMixin,
            FavoritesMixin):