250 lines
7.6 KiB
Python
250 lines
7.6 KiB
Python
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from collections import OrderedDict
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from warnings import warn
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from django.core.exceptions import FieldDoesNotExist
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from django.db import models
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from django.db.models import Count
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from django.db.models.expressions import Value
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from wagtail.search.backends.base import (
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BaseSearchBackend,
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BaseSearchQueryCompiler,
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BaseSearchResults,
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FilterFieldError,
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)
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from wagtail.search.query import And, Boost, MatchAll, Not, Or, Phrase, PlainText
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from wagtail.search.utils import AND, OR
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# This file implements a database search backend using basic substring matching, and no
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# database-specific full-text search capabilities. It will be used in the following cases:
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# * The current default database is SQLite <3.19, or SQLite built without fulltext
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# extensions, or something other than PostgreSQL, MySQL or SQLite
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# * 'wagtail.search.backends.database.fallback' is specified directly as the search backend
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MATCH_ALL = "_ALL_"
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MATCH_NONE = "_NONE_"
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class DatabaseSearchQueryCompiler(BaseSearchQueryCompiler):
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DEFAULT_OPERATOR = "and"
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OPERATORS = {
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"and": AND,
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"or": OR,
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}
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def __init__(self, *args, **kwargs):
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super().__init__(*args, **kwargs)
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self.fields_names = list(self.get_fields_names())
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def get_fields_names(self):
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model = self.queryset.model
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fields_names = self.fields or [
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field.field_name for field in model.get_searchable_search_fields()
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]
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# Check if the field exists (this will filter out indexed callables)
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for field_name in fields_names:
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try:
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model._meta.get_field(field_name)
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except FieldDoesNotExist:
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continue
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else:
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yield field_name
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def _process_lookup(self, field, lookup, value):
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return models.Q(
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**{field.get_attname(self.queryset.model) + "__" + lookup: value}
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)
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def _connect_filters(self, filters, connector, negated):
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if connector == "AND":
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q = models.Q(*filters)
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elif connector == "OR":
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q = OR([models.Q(fil) for fil in filters])
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else:
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return
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if negated:
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q = ~q
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return q
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def build_single_term_filter(self, term):
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term_query = models.Q()
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for field_name in self.fields_names:
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term_query |= models.Q(**{field_name + "__icontains": term})
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return term_query
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def check_boost(self, query, boost=1.0):
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if query.boost * boost != 1.0:
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warn("Database search backend does not support term boosting.")
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def build_database_filter(self, query, boost=1.0):
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if isinstance(query, PlainText):
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self.check_boost(query, boost=boost)
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operator = self.OPERATORS[query.operator]
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return operator(
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[
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self.build_single_term_filter(term)
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for term in query.query_string.split()
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]
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)
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if isinstance(query, Phrase):
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q = models.Q()
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for field_name in self.fields_names:
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q |= models.Q(**{field_name + "__icontains": query.query_string})
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return q
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if isinstance(query, Boost):
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boost *= query.boost
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return self.build_database_filter(query.subquery, boost=boost)
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if isinstance(query, MatchAll):
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return MATCH_ALL
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if isinstance(query, Not):
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q = self.build_database_filter(query.subquery, boost=boost)
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if q == MATCH_ALL:
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return MATCH_NONE
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elif q == MATCH_NONE:
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return MATCH_ALL
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else:
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return ~q
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if isinstance(query, And):
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subqueries = [
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self.build_database_filter(subquery, boost=boost)
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for subquery in query.subqueries
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]
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# If there's a MATCH_NONE, return MATCH_NONE
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if MATCH_NONE in subqueries:
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return MATCH_NONE
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# Ignore MATCH_ALL
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subqueries = [q for q in subqueries if q != MATCH_ALL]
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return AND(subqueries)
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if isinstance(query, Or):
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subqueries = [
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self.build_database_filter(subquery, boost=boost)
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for subquery in query.subqueries
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]
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# If there's a MATCH_ALL, return MATCH_ALL
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if MATCH_ALL in subqueries:
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return MATCH_ALL
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# Ignore MATCH_NONE
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subqueries = [q for q in subqueries if q != MATCH_NONE]
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return OR(subqueries)
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raise NotImplementedError(
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"`%s` is not supported by the database search backend."
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% query.__class__.__name__
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)
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class DatabaseAutocompleteQueryCompiler(DatabaseSearchQueryCompiler):
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# The fallback backend doesn't handle word boundaries, so standard searches are
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# essentially equivalent to autocomplete queries anyhow. However, to provide a
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# consistent API with other backends, we provide both endpoints.
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pass
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class DatabaseSearchResults(BaseSearchResults):
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iterator_chunk_size = 2000
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def get_queryset(self):
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queryset = self.query_compiler.queryset
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# Run _get_filters_from_queryset to test that no fields that are not
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# a FilterField have been used in the query.
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self.query_compiler._get_filters_from_queryset()
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q = self.query_compiler.build_database_filter(self.query_compiler.query)
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if q == MATCH_ALL:
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pass
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elif q == MATCH_NONE:
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queryset = queryset.none()
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else:
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queryset = queryset.filter(q)
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return queryset.distinct()[self.start : self.stop]
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def _do_search(self):
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queryset = self.get_queryset()
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if self._score_field:
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queryset = queryset.annotate(
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**{self._score_field: Value(None, output_field=models.FloatField())}
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)
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return queryset.iterator(self.iterator_chunk_size)
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def _do_count(self):
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return self.get_queryset().count()
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supports_facet = True
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def facet(self, field_name):
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# Get field
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field = self.query_compiler._get_filterable_field(field_name)
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if field is None:
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raise FilterFieldError(
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'Cannot facet search results with field "'
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+ field_name
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+ "\". Please add index.FilterField('"
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+ field_name
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+ "') to "
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+ self.query_compiler.queryset.model.__name__
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+ ".search_fields.",
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field_name=field_name,
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)
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query = self.get_queryset()
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results = (
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query.values(field_name).annotate(count=Count("pk")).order_by("-count")
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)
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return OrderedDict(
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[(result[field_name], result["count"]) for result in results]
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)
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class DatabaseSearchBackend(BaseSearchBackend):
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query_compiler_class = DatabaseSearchQueryCompiler
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autocomplete_query_compiler_class = DatabaseSearchQueryCompiler
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results_class = DatabaseSearchResults
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def reset_index(self):
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pass # Not needed
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def add_type(self, model):
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pass # Not needed
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def refresh_index(self):
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pass # Not needed
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def add(self, obj):
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pass # Not needed
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def add_bulk(self, model, obj_list):
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return # Not needed
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def delete(self, obj):
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pass # Not needed
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# This line allows using 'wagtail.search.backends.database.fallback' as the backend, bypassing the automatic selection of the backend that would get run if the user chose 'wagtail.search.backends.database'
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SearchBackend = DatabaseSearchBackend
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