import re import warnings from collections import OrderedDict from django.db import ( NotSupportedError, connections, router, transaction, ) from django.db.models import Case, When from django.db.models.aggregates import Avg, Count from django.db.models.constants import LOOKUP_SEP from django.db.models.expressions import F from django.db.models.fields import BooleanField, FloatField, TextField from django.db.models.functions.comparison import Cast from django.db.models.functions.text import Length from django.db.models.manager import Manager from django.db.models.query_utils import Q from django.utils.encoding import force_str from django.utils.functional import cached_property from wagtail.search.backends.base import ( BaseSearchBackend, BaseSearchQueryCompiler, BaseSearchResults, FilterFieldError, ) from wagtail.search.backends.database.mysql.query import ( Lexeme, MatchExpression, SearchQuery, ) from wagtail.search.index import ( AutocompleteField, RelatedFields, SearchField, get_indexed_models, ) from wagtail.search.models import IndexEntry from wagtail.search.query import And, Boost, MatchAll, Not, Or, Phrase, PlainText from wagtail.search.utils import ( OR, balanced_reduce, get_content_type_pk, get_descendants_content_types_pks, ) class ObjectIndexer: """ Responsible for extracting data from an object to be inserted into the index. """ def __init__(self, obj, backend): self.obj = obj self.search_fields = obj.get_search_fields() self.config = backend.config def prepare_value(self, value): if isinstance(value, str): return value elif isinstance(value, list): return ", ".join(self.prepare_value(item) for item in value) elif isinstance(value, dict): return ", ".join(self.prepare_value(item) for item in value.values()) return force_str(value) def prepare_field(self, obj, field): if isinstance(field, SearchField): yield (field, self.prepare_value(field.get_value(obj))) elif isinstance(field, AutocompleteField): yield (field, self.prepare_value(field.get_value(obj))) elif isinstance(field, RelatedFields): sub_obj = field.get_value(obj) if sub_obj is None: return if isinstance(sub_obj, Manager): sub_objs = sub_obj.all() else: if callable(sub_obj): sub_obj = sub_obj() sub_objs = [sub_obj] for sub_obj in sub_objs: for sub_field in field.fields: yield from self.prepare_field(sub_obj, sub_field) @cached_property def id(self): """ Returns the value to use as the ID of the record in the index """ return force_str(self.obj.pk) @cached_property def title(self): """ Returns all values to index as "title". This is the value of all SearchFields that have the field_name 'title' """ texts = [] for field in self.search_fields: for current_field, value in self.prepare_field(self.obj, field): if ( isinstance(current_field, SearchField) and current_field.field_name == "title" ): texts.append(value) return " ".join(texts) @cached_property def body(self): """ Returns all values to index as "body". This is the value of all SearchFields excluding the title """ texts = [] for field in self.search_fields: for current_field, value in self.prepare_field(self.obj, field): if ( isinstance(current_field, SearchField) and not current_field.field_name == "title" ): texts.append(value) return " ".join(texts) @cached_property def autocomplete(self): """ Returns all values to index as "autocomplete". This is the value of all AutocompleteFields """ texts = [] for field in self.search_fields: for current_field, value in self.prepare_field(self.obj, field): if isinstance(current_field, AutocompleteField): texts.append(value) return " ".join(texts) def as_vector(self, texts, for_autocomplete=False): """ Converts an array of strings into a SearchVector that can be indexed. """ texts = [(text.strip(), weight) for text, weight in texts] texts = [(text, weight) for text, weight in texts if text] return " ".join(texts) class Index: def __init__(self, backend): self.backend = backend self.name = self.backend.index_name self.read_connection = connections[router.db_for_read(IndexEntry)] self.write_connection = connections[router.db_for_write(IndexEntry)] if ( self.read_connection.vendor != "mysql" or self.write_connection.vendor != "mysql" ): raise NotSupportedError( "You must select a MySQL database to use MySQL search." ) self.entries = IndexEntry._default_manager.all() def add_model(self, model): pass def refresh(self): pass def _refresh_title_norms(self, full=False): """ Refreshes the value of the title_norm field. This needs to be set to 'lavg/ld' where: - lavg is the average length of titles in all documents (also in terms) - ld is the length of the title field in this document (in terms) """ lavg = ( self.entries.annotate(title_length=Length("title")) .filter(title_length__gt=0) .aggregate(Avg("title_length"))["title_length__avg"] ) if full: # Update the whole table # This is the most accurate option but requires a full table rewrite # so we can't do it too often as it could lead to locking issues. entries = self.entries else: # Only update entries where title_norm is 1.0 # This is the default value set on new entries. # It's possible that other entries could have this exact value but there shouldn't be too many of those entries = self.entries.filter(title_norm=1.0) entries.annotate(title_length=Length("title")).filter( title_length__gt=0 ).update(title_norm=lavg / F("title_length")) def delete_stale_model_entries(self, model): existing_pks = model._default_manager.annotate( object_id=Cast("pk", TextField()) ).values("object_id") content_types_pks = get_descendants_content_types_pks(model) stale_entries = self.entries.filter( content_type_id__in=content_types_pks ).exclude(object_id__in=existing_pks) stale_entries.delete() def delete_stale_entries(self): for model in get_indexed_models(): # We don’t need to delete stale entries for non-root models, # since we already delete them by deleting roots. if not model._meta.parents: self.delete_stale_model_entries(model) def add_item(self, obj): self.add_items(obj._meta.model, [obj]) def add_items_update_then_create(self, content_type_pk, indexers): ids_and_data = {} for indexer in indexers: ids_and_data[indexer.id] = ( indexer.title, indexer.autocomplete, indexer.body, ) index_entries_for_ct = self.entries.filter(content_type_id=content_type_pk) indexed_ids = frozenset( index_entries_for_ct.filter(object_id__in=ids_and_data.keys()).values_list( "object_id", flat=True ) ) for indexed_id in indexed_ids: title, autocomplete, body = ids_and_data[indexed_id] index_entries_for_ct.filter(object_id=indexed_id).update( title=title, autocomplete=autocomplete, body=body ) to_be_created = [] for object_id in ids_and_data.keys(): if object_id not in indexed_ids: title, autocomplete, body = ids_and_data[object_id] to_be_created.append( IndexEntry( content_type_id=content_type_pk, object_id=object_id, title=title, autocomplete=autocomplete, body=body, ) ) self.entries.bulk_create(to_be_created) self._refresh_title_norms() def add_items(self, model, objs): search_fields = model.get_search_fields() if not search_fields: return indexers = [ObjectIndexer(obj, self.backend) for obj in objs] # TODO: Delete unindexed objects while dealing with proxy models. if indexers: content_type_pk = get_content_type_pk(model) update_method = self.add_items_update_then_create update_method(content_type_pk, indexers) def delete_item(self, item): item.index_entries.all()._raw_delete(using=self.write_connection.alias) def __str__(self): return self.name class MySQLSearchQueryCompiler(BaseSearchQueryCompiler): DEFAULT_OPERATOR = "and" LAST_TERM_IS_PREFIX = False TARGET_SEARCH_FIELD_TYPE = SearchField FTS_TABLE_FIELDS = ["title", "body"] def __init__(self, *args, **kwargs): super().__init__(*args, **kwargs) local_search_fields = self.get_search_fields_for_model() if self.fields is None: # search over the fields defined on the current model self.search_fields = local_search_fields else: # build a search_fields set from the passed definition, # which may involve traversing relations self.search_fields = { field_lookup: self.get_search_field( field_lookup, fields=local_search_fields ) for field_lookup in self.fields } def get_config(self, backend): return backend.config def get_search_fields_for_model(self): return self.queryset.model.get_searchable_search_fields() def get_search_field(self, field_lookup, fields=None): if fields is None: fields = self.search_fields if LOOKUP_SEP in field_lookup: field_lookup, sub_field_name = field_lookup.split(LOOKUP_SEP, 1) else: sub_field_name = None for field in fields: if ( isinstance(field, self.TARGET_SEARCH_FIELD_TYPE) and field.field_name == field_lookup ): return field # Note: Searching on a specific related field using # `.search(fields=…)` is not yet supported by Wagtail. # This method anticipates by already implementing it. if isinstance(field, RelatedFields) and field.field_name == field_lookup: return self.get_search_field(sub_field_name, field.fields) def build_search_query_content(self, query, invert=False): if isinstance(query, PlainText): # For Boolean full text search queries in MySQL, # non-alphanumeric characters act as separators terms = [term for term in re.split(r"\W+", query.query_string) if term] if not terms: return SearchQuery("") last_term = terms.pop() lexemes = Lexeme(last_term, invert=invert, prefix=self.LAST_TERM_IS_PREFIX) for term in terms: new_lexeme = Lexeme(term, invert=invert) if query.operator == "and": lexemes &= new_lexeme else: lexemes |= new_lexeme return SearchQuery(lexemes) elif isinstance(query, Phrase): return SearchQuery(query.query_string, search_type="phrase") elif isinstance(query, Boost): # Not supported msg = "The Boost query is not supported by the MySQL search backend." warnings.warn(msg, RuntimeWarning) return self.build_search_query_content(query.subquery, invert=invert) elif isinstance(query, Not): return self.build_search_query_content(query.subquery, invert=not invert) elif isinstance(query, (And, Or)): # If this part of the query is inverted, we swap the operator and # pass down the inversion state to the child queries. # This works thanks to De Morgan's law. # # For example, the following query: # # Not(And(Term("A"), Term("B"))) # # Is equivalent to: # # Or(Not(Term("A")), Not(Term("B"))) # # It's simpler to code it this way as we only need to store the # invert status of the terms rather than all the operators. subquery_lexemes = [ self.build_search_query_content(subquery, invert=invert) for subquery in query.subqueries ] is_and = isinstance(query, And) if invert: is_and = not is_and if is_and: return balanced_reduce(lambda a, b: a & b, subquery_lexemes) else: return balanced_reduce(lambda a, b: a | b, subquery_lexemes) raise NotImplementedError( "`%s` is not supported by the MySQL search backend." % query.__class__.__name__ ) def build_search_query(self, query): return self.build_search_query_content(query) def get_index_vectors(self, search_query): return [ (F("index_entries__title"), F("index_entries__title_norm")), (F("index_entries__body"), 1.0), ] def get_fields_vectors(self, search_query): raise NotImplementedError() def get_search_vectors(self, search_query): if self.fields is None: return self.get_index_vectors(search_query) else: return self.get_fields_vectors(search_query) def _build_rank_expression(self, vectors, config): rank_expressions = [ self.build_tsrank(vector, self.query, config=config) * boost for vector, boost in vectors ] rank_expression = rank_expressions[0] for other_rank_expression in rank_expressions[1:]: rank_expression += other_rank_expression return rank_expression def search(self, config, start, stop, score_field=None): # TODO: Handle MatchAll nested inside other search query classes. if isinstance(self.query, MatchAll): return self.queryset[start:stop] elif isinstance(self.query, Not) and isinstance(self.query.subquery, MatchAll): return self.queryset.none() if isinstance( self.query, Not ): # If the outermost operator is a Not, we invert the query. This is done because, if every search term is negated, the Not() will return no results, an we want to match all results instead. query = self.query.subquery negated = True else: query = self.query negated = False search_query = self.build_search_query(query) match_expression = MatchExpression( search_query, columns=self.FTS_TABLE_FIELDS, output_field=BooleanField() ) # For example: MATCH (`title`, `body`) AGAINST ('+query' IN BOOLEAN MODE) # In Django 4.0 the above match expression would produce this SQL WHERE clause: # # WHERE ... MATCH (`title`, `body`) AGAINST (query IN BOOLEAN MODE) # # In Django 4.1, this behavior was changed: # # https://code.djangoproject.com/ticket/32691 # https://github.com/django/django/commit/407fe95cb116599adeb4b9ed01df5673aa5cb1db # # so that instead this SQL WHERE clause is generated, explicitly filtering # against "= True": # # WHERE ... MATCH (`title`, `body`) AGAINST (query IN BOOLEAN MODE) = True # # This no longer works properly because MATCH returns a floating point score # as a measurement of the match quality, not a boolean value: # # https://dev.mysql.com/doc/refman/8.0/en/fulltext-boolean.html # # In order for filtering on "= True" to work, we change the match expression # SQL to be: # # WHERE ... CASE WHEN MATCH (`title`, `body`) AGAINST (query IN BOOLEAN MODE) THEN True ELSE False END = True match_expression = Case(When(match_expression, then=True), default=False) score_expression = MatchExpression( search_query, columns=["title"], output_field=FloatField() ) * F("title_norm") + MatchExpression( search_query, columns=["body"], output_field=FloatField() ) index_entries = IndexEntry.objects.annotate(score=score_expression).filter( content_type_id__in=get_descendants_content_types_pks(self.queryset.model) ) if not negated: index_entries = index_entries.filter(match_expression) if self.order_by_relevance: # Only applies to the case where the outermost query is not a Not(), because if it is, the relevance score is always 0 (anything that matches is excluded from the results). index_entries = index_entries.order_by(score_expression.desc()) else: index_entries = index_entries.exclude(match_expression) index_entries = index_entries[start:stop] # Trim the results object_ids = { index_entry.object_id for index_entry in index_entries } # Get the set of IDs from the indexed objects, removes duplicates too results = self.queryset.filter(id__in=object_ids) return results def _process_lookup(self, field, lookup, value): lhs = field.get_attname(self.queryset.model) + "__" + lookup return Q(**{lhs: value}) def _process_match_none(self): return Q(pk__in=[]) def _connect_filters(self, filters, connector, negated): if connector == "AND": q = Q(*filters) elif connector == "OR": q = OR([Q(fil) for fil in filters]) else: return if negated: q = ~q return q class MySQLAutocompleteQueryCompiler(MySQLSearchQueryCompiler): LAST_TERM_IS_PREFIX = True TARGET_SEARCH_FIELD_TYPE = AutocompleteField FTS_TABLE_FIELDS = ["autocomplete"] def get_config(self, backend): return backend.autocomplete_config def get_search_fields_for_model(self): return self.queryset.model.get_autocomplete_search_fields() def get_index_vectors(self, search_query): return [(F("index_entries__autocomplete"), 1.0)] def get_fields_vectors(self, search_query): raise NotImplementedError() class MySQLSearchResults(BaseSearchResults): def get_queryset(self, for_count=False): if for_count: start = None stop = None else: start = self.start stop = self.stop return self.query_compiler.search( self.query_compiler.get_config(self.backend), start, stop, score_field=self._score_field, ) def _do_search(self): return list(self.get_queryset()) def _do_count(self): return self.get_queryset(for_count=True).count() supports_facet = True def facet(self, field_name): # Get field field = self.query_compiler._get_filterable_field(field_name) if field is None: raise FilterFieldError( 'Cannot facet search results with field "' + field_name + "\". Please add index.FilterField('" + field_name + "') to " + self.query_compiler.queryset.model.__name__ + ".search_fields.", field_name=field_name, ) query = self.query_compiler.search( self.query_compiler.get_config(self.backend), None, None ) results = ( query.values(field_name).annotate(count=Count("pk")).order_by("-count") ) return OrderedDict( [(result[field_name], result["count"]) for result in results] ) class MySQLSearchRebuilder: def __init__(self, index): self.index = index def start(self): self.index.delete_stale_entries() return self.index def finish(self): self.index._refresh_title_norms(full=True) class MySQLSearchAtomicRebuilder(MySQLSearchRebuilder): def __init__(self, index): super().__init__(index) self.transaction = transaction.atomic(using=index.write_connection.alias) self.transaction_opened = False def start(self): self.transaction.__enter__() self.transaction_opened = True return super().start() def finish(self): self.index._refresh_title_norms(full=True) self.transaction.__exit__(None, None, None) self.transaction_opened = False def __del__(self): # TODO: Implement a cleaner way to close the connection on failure. if self.transaction_opened: self.transaction.needs_rollback = True self.finish() class MySQLSearchBackend(BaseSearchBackend): query_compiler_class = MySQLSearchQueryCompiler autocomplete_query_compiler_class = MySQLAutocompleteQueryCompiler results_class = MySQLSearchResults rebuilder_class = MySQLSearchRebuilder atomic_rebuilder_class = MySQLSearchAtomicRebuilder def __init__(self, params): super().__init__(params) self.index_name = params.get("INDEX", "default") # MySQL backend currently has no config options self.config = None self.autocomplete_config = None if params.get("ATOMIC_REBUILD", False): self.rebuilder_class = self.atomic_rebuilder_class def get_index_for_model(self, model): return Index(self) def get_index_for_object(self, obj): return self.get_index_for_model(obj._meta.model) def reset_index(self): for connection in [ connection for connection in connections.all() if connection.vendor == "mysql" ]: IndexEntry._default_manager.all()._raw_delete(using=connection.alias) def add_type(self, model): pass # Not needed. def refresh_index(self): pass # Not needed. def add(self, obj): self.get_index_for_object(obj).add_item(obj) def add_bulk(self, model, obj_list): if obj_list: self.get_index_for_object(obj_list[0]).add_items(model, obj_list) def delete(self, obj): self.get_index_for_object(obj).delete_item(obj) SearchBackend = MySQLSearchBackend