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SearchBackend API

The SearchBackend class handles interaction directly with the backend. The search query it performs is usually fed to it from a SearchQuery class that has been built for that backend.

This class must be at least partially implemented on a per-backend basis and is usually accompanied by a SearchQuery class within the same module.

Unless you are writing a new backend, it is unlikely you need to directly access this class.

Method Reference

update

.. method:: SearchBackend.update(self, index, iterable)

Updates the backend when given a SearchIndex and a collection of documents.

This method MUST be implemented by each backend, as it will be highly specific to each one.

remove

.. method:: SearchBackend.remove(self, obj_or_string)

Removes a document/object from the backend. Can be either a model instance or the identifier (i.e. app_name.model_name.id) in the event the object no longer exists.

This method MUST be implemented by each backend, as it will be highly specific to each one.

clear

.. method:: SearchBackend.clear(self, models=[])

Clears the backend of all documents/objects for a collection of models.

This method MUST be implemented by each backend, as it will be highly specific to each one.

search

.. method:: SearchBackend.search(self, query_string, sort_by=None, start_offset=0, end_offset=None, fields='', highlight=False, facets=None, date_facets=None, query_facets=None, narrow_queries=None, spelling_query=None, limit_to_registered_models=None, result_class=None, **kwargs)

Takes a query to search on and returns a dictionary.

The query should be a string that is appropriate syntax for the backend.

The returned dictionary should contain the keys 'results' and 'hits'. The 'results' value should be an iterable of populated SearchResult objects. The 'hits' should be an integer count of the number of matched results the search backend found.

This method MUST be implemented by each backend, as it will be highly specific to each one.

extract_file_contents

.. method:: SearchBackend.extract_file_contents(self, file_obj)

Perform text extraction on the provided file or file-like object. Returns either None or a dictionary containing the keys contents and metadata. The contents field will always contain the extracted text content returned by the underlying search engine but metadata may vary considerably based on the backend and the input file.

prep_value

.. method:: SearchBackend.prep_value(self, value)

Hook to give the backend a chance to prep an attribute value before sending it to the search engine.

By default, just force it to unicode.

more_like_this

.. method:: SearchBackend.more_like_this(self, model_instance, additional_query_string=None, result_class=None)

Takes a model object and returns results the backend thinks are similar.

This method MUST be implemented by each backend, as it will be highly specific to each one.

build_schema

.. method:: SearchBackend.build_schema(self, fields)

Takes a dictionary of fields and returns schema information.

This method MUST be implemented by each backend, as it will be highly specific to each one.

build_models_list

.. method:: SearchBackend.build_models_list(self)

Builds a list of models for searching.

The search method should use this and the django_ct field to narrow the results (unless the user indicates not to). This helps ignore any results that are not currently handled models and ensures consistent caching.

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