Search in Django

1. Search in Django
Lucas Lira Gomes <@x8lucas8x>

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Lucas Lira Gomes
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3. Many faces of search

4. Filtering

5. Faceting

6. Autocomplete

7. Highlighting

8. Spatial search

9. Haystack to the rescue

10. Django Haystack
● Search framework for Django
○ Filtering
○ Faceting
○ Autocompletion
○ Highlighting
○ Spatial search

11. Django Haystack
● Many backends
○ Apache Solr
○ Elasticsearch
○ Whoosh
○ Xapian
○ Simple

12. Installation

13. Django Haystack
● pip install django-haystack

14. Django Haystack
● Add to the apps
INSTALLED_APPS = [
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.sites',
# Added.
'haystack',
# Then your usual apps...
'blog',
]

15. Django Haystack
● Setup a connection
import os
HAYSTACK_CONNECTIONS = {
'default': {
'ENGINE': 'haystack.backends.whoosh_backend.WhooshEngine',
'PATH': os.path.join(os.path.dirname(__file__), 'whoosh_index'),
},
}

16. Django Haystack
● Now what?
a. Define a SearchIndex
b. Index the data
c. Expose it

17. Coding

18. Django Haystack
from haystack import indexes
from my_app.models import MyModel
class MyModelIndex(indexes.ModelSearchIndex,
indexes.Indexable):
hash_id = indexes.CharField()
text = indexes.CharField(document=True,
model_attr='name')
autocomplete = indexes.EdgeNgramField()
num_people = indexes.IntegerField()
@staticmethod
def prepare_hash_id(obj):
return obj.hash_id
@staticmethod
def prepare_num_people(obj):
return len(obj.people.all())
@staticmethod
def prepare_autocomplete(obj):
return " ".join((obj.category, obj.name))
def index_queryset(self, using=None):
return self.get_model().objects.all().prefetch_related('people')
def get_updated_field(obj):
return 'updated_at'
class Meta:
model = MyModel
fields = ('hash_id', 'text', 'num_people')

19. Django Haystack
● Reindexing
○ manage.py clean_index
○ manage.py rebuild_index
○ manage.py update_index
■ --age=<num_hours>
■ --remove

20. Django Haystack
● Expose it
○ Built-in CBVs
■ SearchView
■ FacetedSearchView
○ DRF-Haystack
■ HaystackViewSet
■ HaystackGenericAPIView

21. Django Haystack
class MySearchSerializer(HaystackSerializer):
name = serializers.CharField(source='text')
class Meta:
index_classes = (MyModelIndex, )
fields = ('hash_id', 'name')
ignore_fields = ('autocomplete', 'num_people')
field_aliases = {'q': 'autocomplete'}
class AutocompleteMySearchView(HaystackViewSet):
index_models = (MyModel, )
serializer_class = MySearchSerializer
filter_backends = (HaystackFilter, OrderingFilter)
ordering_fields = ('num_people',)
ordering = ('-num_people',)

22. Django Haystack
● DRF-Haystack
○ Many filter_backends
■ HaystackFilter
■ HaystackFacetFilter
■ HaystackAutocompleteFilter
■ HaystackBoostFilter
■ HaystackHighlightFilter
■ HaystackGEOSpatialFilter

23. Django Haystack
● Best practices
○ “Good search requires good content”
○ Custom search fields
○ Avoid reindexing
■ Get_updated_field
■ SignalProcessors

24. References
1. http://haystacksearch.org/
2. https://django-haystack.readthedocs.io/
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25. Search in Django
Lucas Lira Gomes <@x8lucas8x>