from django.db.models import (
CharField,
Expression,
Field,
FloatField,
Func,
Lookup,
TextField,
Value,
)
from django.db.models.expressions import CombinedExpression, register_combinable_fields
from django.db.models.functions import Cast, Coalesce
class SearchVectorExact(Lookup):
lookup_name = "exact"
def process_rhs(self, qn, connection):
if not isinstance(self.rhs, (SearchQuery, CombinedSearchQuery)):
config = getattr(self.lhs, "config", None)
self.rhs = SearchQuery(self.rhs, config=config)
rhs, rhs_params = super().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" % (lhs, rhs), params
class SearchQueryField(Field):
def db_type(self, connection):
return "tsquery"
class _Float4Field(Field):
def db_type(self, connection):
return "float4"
class SearchConfig(Expression):
def __init__(self, config):
super().__init__()
if not hasattr(config, "resolve_expression"):
config = Value(config)
self.config = config
@classmethod
def from_parameter(cls, config):
if config is None or isinstance(config, cls):
return config
return cls(config)
def get_source_expressions(self):
return [self.config]
def set_source_expressions(self, exprs):
(self.config,) = exprs
def as_sql(self, compiler, connection):
sql, params = compiler.compile(self.config)
return "%s::regconfig" % sql, params
class SearchVectorCombinable:
ADD = "||"
def _combine(self, other, connector, reversed):
if not isinstance(other, SearchVectorCombinable):
raise TypeError(
"SearchVector can only be combined with other SearchVector "
"instances, got %s." % type(other).__name__
)
if reversed:
return CombinedSearchVector(other, connector, self, self.config)
return CombinedSearchVector(self, connector, other, self.config)
register_combinable_fields(
SearchVectorField, SearchVectorCombinable.ADD, SearchVectorField, SearchVectorField
)
[文档]
class SearchVector(SearchVectorCombinable, Func):
function = "to_tsvector"
arg_joiner = " || ' ' || "
output_field = SearchVectorField()
def __init__(self, *expressions, config=None, weight=None):
super().__init__(*expressions)
self.config = SearchConfig.from_parameter(config)
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().resolve_expression(
query, allow_joins, reuse, summarize, for_save
)
if self.config:
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):
clone = self.copy()
clone.set_source_expressions(
[
Coalesce(
expression
if isinstance(expression.output_field, (CharField, TextField))
else Cast(expression, TextField()),
Value(""),
)
for expression in clone.get_source_expressions()
]
)
config_sql = None
config_params = []
if template is None:
if clone.config:
config_sql, config_params = compiler.compile(clone.config)
template = "%(function)s(%(config)s, %(expressions)s)"
else:
template = clone.template
sql, params = super(SearchVector, clone).as_sql(
compiler,
connection,
function=function,
template=template,
config=config_sql,
)
extra_params = []
if clone.weight:
weight_sql, extra_params = compiler.compile(clone.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().__init__(lhs, connector, rhs, output_field)
class SearchQueryCombinable:
BITAND = "&&"
BITOR = "||"
def _combine(self, other, connector, reversed):
if not isinstance(other, SearchQueryCombinable):
raise TypeError(
"SearchQuery can only be combined with other SearchQuery "
"instances, got %s." % type(other).__name__
)
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)
[文档]
class SearchQuery(SearchQueryCombinable, Func):
output_field = SearchQueryField()
SEARCH_TYPES = {
"plain": "plainto_tsquery",
"phrase": "phraseto_tsquery",
"raw": "to_tsquery",
"websearch": "websearch_to_tsquery",
}
def __init__(
self,
value,
output_field=None,
*,
config=None,
invert=False,
search_type="plain",
):
self.function = self.SEARCH_TYPES.get(search_type)
if self.function is None:
raise ValueError("Unknown search_type argument '%s'." % search_type)
if not hasattr(value, "resolve_expression"):
value = Value(value)
expressions = (value,)
self.config = SearchConfig.from_parameter(config)
if self.config is not None:
expressions = (self.config,) + expressions
self.invert = invert
super().__init__(*expressions, output_field=output_field)
def as_sql(self, compiler, connection, function=None, template=None):
sql, params = super().as_sql(compiler, connection, function, template)
if self.invert:
sql = "!!(%s)" % sql
return sql, params
def __invert__(self):
clone = self.copy()
clone.invert = not self.invert
return clone
def __str__(self):
result = super().__str__()
return ("~%s" % result) if self.invert else result
class CombinedSearchQuery(SearchQueryCombinable, CombinedExpression):
def __init__(self, lhs, connector, rhs, config, output_field=None):
self.config = config
super().__init__(lhs, connector, rhs, output_field)
def __str__(self):
return "(%s)" % super().__str__()
[文档]
class SearchRank(Func):
function = "ts_rank"
output_field = FloatField()
def __init__(
self,
vector,
query,
weights=None,
normalization=None,
cover_density=False,
):
from .fields.array import ArrayField
if not hasattr(vector, "resolve_expression"):
vector = SearchVector(vector)
if not hasattr(query, "resolve_expression"):
query = SearchQuery(query)
expressions = (vector, query)
if weights is not None:
if not hasattr(weights, "resolve_expression"):
weights = Value(weights)
weights = Cast(weights, ArrayField(_Float4Field()))
expressions = (weights,) + expressions
if normalization is not None:
if not hasattr(normalization, "resolve_expression"):
normalization = Value(normalization)
expressions += (normalization,)
if cover_density:
self.function = "ts_rank_cd"
super().__init__(*expressions)
[文档]
class SearchHeadline(Func):
function = "ts_headline"
template = "%(function)s(%(expressions)s%(options)s)"
output_field = TextField()
def __init__(
self,
expression,
query,
*,
config=None,
start_sel=None,
stop_sel=None,
max_words=None,
min_words=None,
short_word=None,
highlight_all=None,
max_fragments=None,
fragment_delimiter=None,
):
if not hasattr(query, "resolve_expression"):
query = SearchQuery(query)
options = {
"StartSel": start_sel,
"StopSel": stop_sel,
"MaxWords": max_words,
"MinWords": min_words,
"ShortWord": short_word,
"HighlightAll": highlight_all,
"MaxFragments": max_fragments,
"FragmentDelimiter": fragment_delimiter,
}
self.options = {
option: value for option, value in options.items() if value is not None
}
expressions = (expression, query)
if config is not None:
config = SearchConfig.from_parameter(config)
expressions = (config,) + expressions
super().__init__(*expressions)
def as_sql(self, compiler, connection, function=None, template=None):
options_sql = ""
options_params = []
if self.options:
options_params.append(
", ".join(
connection.ops.compose_sql(f"{option}=%s", [value])
for option, value in self.options.items()
)
)
options_sql = ", %s"
sql, params = super().as_sql(
compiler,
connection,
function=function,
template=template,
options=options_sql,
)
return sql, params + options_params
SearchVectorField.register_lookup(SearchVectorExact)
class TrigramBase(Func):
output_field = FloatField()
def __init__(self, expression, string, **extra):
if not hasattr(string, "resolve_expression"):
string = Value(string)
super().__init__(expression, string, **extra)
class TrigramWordBase(Func):
output_field = FloatField()
def __init__(self, string, expression, **extra):
if not hasattr(string, "resolve_expression"):
string = Value(string)
super().__init__(string, expression, **extra)
12月 18, 2023