220 lines
8.1 KiB
Python
220 lines
8.1 KiB
Python
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from django.db.models import Field, FloatField
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from django.db.models.expressions import CombinedExpression, Func, Value
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from django.db.models.functions import Coalesce
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from django.db.models.lookups import Lookup
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class SearchVectorExact(Lookup):
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lookup_name = 'exact'
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def process_rhs(self, qn, connection):
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if not hasattr(self.rhs, 'resolve_expression'):
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config = getattr(self.lhs, 'config', None)
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self.rhs = SearchQuery(self.rhs, config=config)
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rhs, rhs_params = super().process_rhs(qn, connection)
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return rhs, rhs_params
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def as_sql(self, qn, connection):
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lhs, lhs_params = self.process_lhs(qn, connection)
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rhs, rhs_params = self.process_rhs(qn, connection)
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params = lhs_params + rhs_params
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return '%s @@ %s = true' % (lhs, rhs), params
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class SearchVectorField(Field):
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def db_type(self, connection):
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return 'tsvector'
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class SearchQueryField(Field):
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def db_type(self, connection):
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return 'tsquery'
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class SearchVectorCombinable:
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ADD = '||'
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def _combine(self, other, connector, reversed):
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if not isinstance(other, SearchVectorCombinable) or not self.config == other.config:
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raise TypeError('SearchVector can only be combined with other SearchVectors')
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if reversed:
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return CombinedSearchVector(other, connector, self, self.config)
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return CombinedSearchVector(self, connector, other, self.config)
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class SearchVector(SearchVectorCombinable, Func):
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function = 'to_tsvector'
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arg_joiner = " || ' ' || "
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output_field = SearchVectorField()
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config = None
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def __init__(self, *expressions, **extra):
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super().__init__(*expressions, **extra)
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self.source_expressions = [
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Coalesce(expression, Value('')) for expression in self.source_expressions
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]
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self.config = self.extra.get('config', self.config)
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weight = self.extra.get('weight')
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if weight is not None and not hasattr(weight, 'resolve_expression'):
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weight = Value(weight)
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self.weight = weight
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def resolve_expression(self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False):
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resolved = super().resolve_expression(query, allow_joins, reuse, summarize, for_save)
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if self.config:
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if not hasattr(self.config, 'resolve_expression'):
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resolved.config = Value(self.config).resolve_expression(query, allow_joins, reuse, summarize, for_save)
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else:
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resolved.config = self.config.resolve_expression(query, allow_joins, reuse, summarize, for_save)
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return resolved
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def as_sql(self, compiler, connection, function=None, template=None):
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config_params = []
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if template is None:
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if self.config:
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config_sql, config_params = compiler.compile(self.config)
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template = "%(function)s({}::regconfig, %(expressions)s)".format(config_sql.replace('%', '%%'))
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else:
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template = self.template
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sql, params = super().as_sql(compiler, connection, function=function, template=template)
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extra_params = []
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if self.weight:
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weight_sql, extra_params = compiler.compile(self.weight)
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sql = 'setweight({}, {})'.format(sql, weight_sql)
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return sql, config_params + params + extra_params
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class CombinedSearchVector(SearchVectorCombinable, CombinedExpression):
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def __init__(self, lhs, connector, rhs, config, output_field=None):
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self.config = config
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super().__init__(lhs, connector, rhs, output_field)
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class SearchQueryCombinable:
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BITAND = '&&'
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BITOR = '||'
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def _combine(self, other, connector, reversed):
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if not isinstance(other, SearchQueryCombinable):
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raise TypeError(
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'SearchQuery can only be combined with other SearchQuerys, '
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'got {}.'.format(type(other))
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)
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if not self.config == other.config:
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raise TypeError("SearchQuery configs don't match.")
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if reversed:
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return CombinedSearchQuery(other, connector, self, self.config)
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return CombinedSearchQuery(self, connector, other, self.config)
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# On Combinable, these are not implemented to reduce confusion with Q. In
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# this case we are actually (ab)using them to do logical combination so
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# it's consistent with other usage in Django.
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def __or__(self, other):
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return self._combine(other, self.BITOR, False)
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def __ror__(self, other):
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return self._combine(other, self.BITOR, True)
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def __and__(self, other):
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return self._combine(other, self.BITAND, False)
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def __rand__(self, other):
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return self._combine(other, self.BITAND, True)
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class SearchQuery(SearchQueryCombinable, Value):
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output_field = SearchQueryField()
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def __init__(self, value, output_field=None, *, config=None, invert=False):
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self.config = config
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self.invert = invert
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super().__init__(value, output_field=output_field)
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def resolve_expression(self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False):
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resolved = super().resolve_expression(query, allow_joins, reuse, summarize, for_save)
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if self.config:
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if not hasattr(self.config, 'resolve_expression'):
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resolved.config = Value(self.config).resolve_expression(query, allow_joins, reuse, summarize, for_save)
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else:
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resolved.config = self.config.resolve_expression(query, allow_joins, reuse, summarize, for_save)
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return resolved
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def as_sql(self, compiler, connection):
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params = [self.value]
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if self.config:
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config_sql, config_params = compiler.compile(self.config)
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template = 'plainto_tsquery({}::regconfig, %s)'.format(config_sql)
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params = config_params + [self.value]
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else:
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template = 'plainto_tsquery(%s)'
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if self.invert:
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template = '!!({})'.format(template)
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return template, params
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def _combine(self, other, connector, reversed):
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combined = super()._combine(other, connector, reversed)
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combined.output_field = SearchQueryField()
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return combined
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def __invert__(self):
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return type(self)(self.value, config=self.config, invert=not self.invert)
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class CombinedSearchQuery(SearchQueryCombinable, CombinedExpression):
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def __init__(self, lhs, connector, rhs, config, output_field=None):
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self.config = config
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super().__init__(lhs, connector, rhs, output_field)
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class SearchRank(Func):
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function = 'ts_rank'
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output_field = FloatField()
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def __init__(self, vector, query, **extra):
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if not hasattr(vector, 'resolve_expression'):
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vector = SearchVector(vector)
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if not hasattr(query, 'resolve_expression'):
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query = SearchQuery(query)
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weights = extra.get('weights')
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if weights is not None and not hasattr(weights, 'resolve_expression'):
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weights = Value(weights)
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self.weights = weights
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super().__init__(vector, query, **extra)
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def as_sql(self, compiler, connection, function=None, template=None):
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extra_params = []
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extra_context = {}
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if template is None and self.extra.get('weights'):
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if self.weights:
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template = '%(function)s(%(weights)s, %(expressions)s)'
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weight_sql, extra_params = compiler.compile(self.weights)
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extra_context['weights'] = weight_sql
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sql, params = super().as_sql(
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compiler, connection,
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function=function, template=template, **extra_context
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)
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return sql, extra_params + params
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SearchVectorField.register_lookup(SearchVectorExact)
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class TrigramBase(Func):
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output_field = FloatField()
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def __init__(self, expression, string, **extra):
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if not hasattr(string, 'resolve_expression'):
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string = Value(string)
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super().__init__(expression, string, **extra)
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class TrigramSimilarity(TrigramBase):
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function = 'SIMILARITY'
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class TrigramDistance(TrigramBase):
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function = ''
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arg_joiner = ' <-> '
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