Source code for annotations.elasticsearch_backends

from haystack.backends.elasticsearch2_backend import Elasticsearch2SearchBackend, Elasticsearch2SearchEngine
from haystack.models import SearchResult
import elasticsearch

class JHBElasticsearch2SearchBackend(Elasticsearch2SearchBackend):
    RESERVED_CHARACTERS = (
        '\\', '+', '-', '&&', '||', '!', '(', ')', '{', '}',
        '[', ']', '^', '"', '~',  ':', '/', #'*', '?',
    )

    DEFAULT_SETTINGS = {
        'settings': {
            "analysis": {
                "analyzer": {
                    "ngram_analyzer": {
                        "type": "custom",
                        "tokenizer": "standard",
                        "filter": ["haystack_ngram", "lowercase"]
                    },
                    "edgengram_analyzer": {
                        "type": "custom",
                        "tokenizer": "standard",
                        "filter": ["haystack_edgengram", "lowercase"]
                    }
                },
                "tokenizer": {
                    "haystack_ngram_tokenizer": {
                        "type": "nGram",
                        "min_gram": 3,
                        "max_gram": 15,
                    },
                    "haystack_edgengram_tokenizer": {
                        "type": "edgeNGram",
                        "min_gram": 3,
                        "max_gram": 15,
                        "side": "front"
                    }
                },
                "filter": {
                    "haystack_ngram": {
                        "type": "nGram",
                        "min_gram": 3,
                        "max_gram": 15
                    },
                    "haystack_edgengram": {
                        "type": "edgeNGram",
                        "min_gram": 3,
                        "max_gram": 15
                    }
                }
            }
        }
    }

    def search(self, query_string, **kwargs):
        if len(query_string) == 0:
            return {
                'results': [],
                'hits': 0,
            }

        if not self.setup_complete:
            self.setup()

        search_kwargs = self.build_search_kwargs(query_string, **kwargs)
        search_kwargs['from'] = kwargs.get('start_offset', 0)

        order_fields = set()
        for order in search_kwargs.get('sort', []):
            for key in order.keys():
                order_fields.add(key)

        geo_sort = '_geo_distance' in order_fields

        end_offset = kwargs.get('end_offset')
        start_offset = kwargs.get('start_offset', 0)
        if end_offset is not None and end_offset > start_offset:
            search_kwargs['size'] = end_offset - start_offset

        try:
            raw_results = self.conn.search(body=search_kwargs,
                                           index=self.index_name,
                                           doc_type='modelresult',
                                           _source=True)
        except elasticsearch.TransportError as e:
            if not self.silently_fail:
                raise

            self.log.error("Failed to query Elasticsearch using '%s': %s", query_string, e, exc_info=True)
            raw_results = {}

        return self._process_results(raw_results,
                                     highlight=kwargs.get('highlight'),
                                     result_class=kwargs.get('result_class', SearchResult),
                                     distance_point=kwargs.get('distance_point'),
                                     geo_sort=geo_sort)

class JHBElasticsearch2SearchEngine(Elasticsearch2SearchEngine):
    backend = JHBElasticsearch2SearchBackend