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