516 lines
17 KiB
Python
516 lines
17 KiB
Python
from typing import (
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Any,
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Dict,
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List,
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NamedTuple,
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Optional,
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TYPE_CHECKING,
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Tuple,
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Type,
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Union,
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)
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import databases
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import orm
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from orm import ForeignKey
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from orm.exceptions import MultipleMatches, NoMatch, QueryDefinitionError
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from orm.fields import BaseField
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import sqlalchemy
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from sqlalchemy import text
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if TYPE_CHECKING: # pragma no cover
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from orm.models import Model
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FILTER_OPERATORS = {
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"exact": "__eq__",
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"iexact": "ilike",
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"contains": "like",
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"icontains": "ilike",
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"in": "in_",
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"gt": "__gt__",
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"gte": "__ge__",
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"lt": "__lt__",
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"lte": "__le__",
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}
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class JoinParameters(NamedTuple):
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prev_model: Type["Model"]
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previous_alias: str
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from_table: str
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model_cls: Type["Model"]
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class QuerySet:
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ESCAPE_CHARACTERS = ["%", "_"]
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def __init__(
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self,
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model_cls: Type["Model"] = None,
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filter_clauses: List = None,
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select_related: List = None,
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limit_count: int = None,
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offset: int = None,
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) -> None:
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self.model_cls = model_cls
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self.filter_clauses = [] if filter_clauses is None else filter_clauses
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self._select_related = [] if select_related is None else select_related
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self.limit_count = limit_count
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self.query_offset = offset
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self.auto_related = []
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self.used_aliases = []
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self.select_from = None
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self.columns = None
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self.order_bys = None
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def __get__(self, instance: "QuerySet", owner: Type["Model"]) -> "QuerySet":
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return self.__class__(model_cls=owner)
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@property
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def database(self) -> databases.Database:
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return self.model_cls.__database__
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@property
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def table(self) -> sqlalchemy.Table:
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return self.model_cls.__table__
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@staticmethod
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def prefixed_columns(alias: str, table: sqlalchemy.Table) -> List[text]:
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return [
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text(f"{alias}_{table.name}.{column.name} as {alias}_{column.name}")
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for column in table.columns
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]
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@staticmethod
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def prefixed_table_name(alias: str, name: str) -> text:
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return text(f"{name} {alias}_{name}")
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def on_clause(
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self, previous_alias: str, alias: str, from_clause: str, to_clause: str,
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) -> text:
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left_part = f"{alias}_{to_clause}"
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right_part = f"{previous_alias + '_' if previous_alias else ''}{from_clause}"
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return text(f"{left_part}={right_part}")
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def _build_join_parameters(
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self, part: str, join_params: JoinParameters
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) -> JoinParameters:
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model_cls = join_params.model_cls.__model_fields__[part].to
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to_table = model_cls.__table__.name
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alias = model_cls._orm_relationship_manager.resolve_relation_join(
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join_params.from_table, to_table
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)
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if alias not in self.used_aliases:
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if join_params.prev_model.__model_fields__[part].virtual:
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to_key = next(
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(
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v
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for k, v in model_cls.__model_fields__.items()
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if isinstance(v, ForeignKey) and v.to == join_params.prev_model
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),
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None,
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).name
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from_key = model_cls.__pkname__
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else:
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to_key = model_cls.__pkname__
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from_key = part
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on_clause = self.on_clause(
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previous_alias=join_params.previous_alias,
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alias=alias,
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from_clause=f"{join_params.from_table}.{from_key}",
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to_clause=f"{to_table}.{to_key}",
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)
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target_table = self.prefixed_table_name(alias, to_table)
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self.select_from = sqlalchemy.sql.outerjoin(
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self.select_from, target_table, on_clause
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)
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self.order_bys.append(text(f"{alias}_{to_table}.{model_cls.__pkname__}"))
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self.columns.extend(self.prefixed_columns(alias, model_cls.__table__))
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self.used_aliases.append(alias)
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previous_alias = alias
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from_table = to_table
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prev_model = model_cls
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return JoinParameters(prev_model, previous_alias, from_table, model_cls)
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@staticmethod
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def _field_is_a_foreign_key_and_no_circular_reference(
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field: BaseField, field_name: str, rel_part: str
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) -> bool:
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return isinstance(field, ForeignKey) and field_name not in rel_part
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def _field_qualifies_to_deeper_search(
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self, field: ForeignKey, parent_virtual: bool, nested: bool, rel_part: str
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) -> bool:
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prev_part_of_related = "__".join(rel_part.split("__")[:-1])
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partial_match = any(
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[x.startswith(prev_part_of_related) for x in self._select_related]
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)
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already_checked = any([x.startswith(rel_part) for x in self.auto_related])
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return (
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(field.virtual and parent_virtual)
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or (partial_match and not already_checked)
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) or not nested
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def _extract_auto_required_relations(
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self,
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prev_model: Type["Model"],
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rel_part: str = "",
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nested: bool = False,
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parent_virtual: bool = False,
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) -> None:
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for field_name, field in prev_model.__model_fields__.items():
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if self._field_is_a_foreign_key_and_no_circular_reference(
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field, field_name, rel_part
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):
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rel_part = field_name if not rel_part else rel_part + "__" + field_name
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if not field.nullable:
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if rel_part not in self._select_related:
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self.auto_related.append("__".join(rel_part.split("__")[:-1]))
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rel_part = ""
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elif self._field_qualifies_to_deeper_search(
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field, parent_virtual, nested, rel_part
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):
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self._extract_auto_required_relations(
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prev_model=field.to,
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rel_part=rel_part,
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nested=True,
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parent_virtual=field.virtual,
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)
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else:
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rel_part = ""
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def _include_auto_related_models(self) -> None:
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if self.auto_related:
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new_joins = []
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for join in self._select_related:
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if not any([x.startswith(join) for x in self.auto_related]):
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new_joins.append(join)
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self._select_related = new_joins + self.auto_related
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def _apply_expression_modifiers(
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self, expr: sqlalchemy.sql.select
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) -> sqlalchemy.sql.select:
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if self.filter_clauses:
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if len(self.filter_clauses) == 1:
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clause = self.filter_clauses[0]
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else:
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clause = sqlalchemy.sql.and_(*self.filter_clauses)
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expr = expr.where(clause)
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if self.limit_count:
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expr = expr.limit(self.limit_count)
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if self.query_offset:
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expr = expr.offset(self.query_offset)
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for order in self.order_bys:
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expr = expr.order_by(order)
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return expr
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def _reset_query_parameters(self) -> None:
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self.select_from = None
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self.columns = None
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self.order_bys = None
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self.auto_related = []
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self.used_aliases = []
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def build_select_expression(self) -> sqlalchemy.sql.select:
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self.columns = list(self.table.columns)
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self.order_bys = [text(f"{self.table.name}.{self.model_cls.__pkname__}")]
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self.select_from = self.table
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for key in self.model_cls.__model_fields__:
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if (
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not self.model_cls.__model_fields__[key].nullable
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and isinstance(
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self.model_cls.__model_fields__[key], orm.fields.ForeignKey
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)
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and key not in self._select_related
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):
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self._select_related = [key] + self._select_related
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start_params = JoinParameters(
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self.model_cls, "", self.table.name, self.model_cls
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)
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self._extract_auto_required_relations(prev_model=start_params.prev_model)
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self._include_auto_related_models()
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self._select_related.sort(key=lambda item: (-len(item), item))
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for item in self._select_related:
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join_parameters = JoinParameters(
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self.model_cls, "", self.table.name, self.model_cls
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)
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for part in item.split("__"):
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join_parameters = self._build_join_parameters(part, join_parameters)
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expr = sqlalchemy.sql.select(self.columns)
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expr = expr.select_from(self.select_from)
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expr = self._apply_expression_modifiers(expr)
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# print(expr.compile(compile_kwargs={"literal_binds": True}))
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self._reset_query_parameters()
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return expr
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def _determine_filter_target_table(
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self, related_parts: List[str], select_related: List[str]
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) -> Tuple[List[str], str, "Model"]:
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table_prefix = ""
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model_cls = self.model_cls
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select_related = [relation for relation in select_related]
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# Add any implied select_related
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related_str = "__".join(related_parts)
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if related_str not in select_related:
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select_related.append(related_str)
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# Walk the relationships to the actual model class
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# against which the comparison is being made.
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previous_table = model_cls.__tablename__
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for part in related_parts:
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current_table = model_cls.__model_fields__[part].to.__tablename__
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manager = model_cls._orm_relationship_manager
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table_prefix = manager.resolve_relation_join(previous_table, current_table)
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model_cls = model_cls.__model_fields__[part].to
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previous_table = current_table
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return select_related, table_prefix, model_cls
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def _compile_clause(
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self,
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clause: sqlalchemy.sql.expression.BinaryExpression,
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column: sqlalchemy.Column,
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table: sqlalchemy.Table,
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table_prefix: str,
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modifiers: Dict,
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) -> sqlalchemy.sql.expression.TextClause:
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for modifier, modifier_value in modifiers.items():
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clause.modifiers[modifier] = modifier_value
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clause_text = str(
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clause.compile(
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dialect=self.model_cls.__database__._backend._dialect,
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compile_kwargs={"literal_binds": True},
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)
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)
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alias = f"{table_prefix}_" if table_prefix else ""
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aliased_name = f"{alias}{table.name}.{column.name}"
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clause_text = clause_text.replace(f"{table.name}.{column.name}", aliased_name)
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clause = text(clause_text)
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return clause
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def _escape_characters_in_clause(
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self, op: str, value: Union[str, "Model"]
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) -> Tuple[str, bool]:
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has_escaped_character = False
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if op in ["contains", "icontains"]:
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if isinstance(value, orm.Model):
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raise QueryDefinitionError(
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"You cannot use contains and icontains with instance of the Model"
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)
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has_escaped_character = any(c for c in self.ESCAPE_CHARACTERS if c in value)
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if has_escaped_character:
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# enable escape modifier
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for char in self.ESCAPE_CHARACTERS:
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value = value.replace(char, f"\\{char}")
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value = f"%{value}%"
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return value, has_escaped_character
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@staticmethod
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def _extract_operator_field_and_related(
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parts: List[str],
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) -> Tuple[str, str, Optional[List]]:
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if parts[-1] in FILTER_OPERATORS:
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op = parts[-1]
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field_name = parts[-2]
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related_parts = parts[:-2]
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else:
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op = "exact"
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field_name = parts[-1]
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related_parts = parts[:-1]
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return op, field_name, related_parts
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def filter(self, **kwargs: Any) -> "QuerySet": # noqa: A003
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filter_clauses = self.filter_clauses
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select_related = list(self._select_related)
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if kwargs.get("pk"):
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pk_name = self.model_cls.__pkname__
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kwargs[pk_name] = kwargs.pop("pk")
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for key, value in kwargs.items():
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table_prefix = ""
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if "__" in key:
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parts = key.split("__")
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(
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op,
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field_name,
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related_parts,
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) = self._extract_operator_field_and_related(parts)
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model_cls = self.model_cls
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if related_parts:
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(
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select_related,
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table_prefix,
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model_cls,
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) = self._determine_filter_target_table(
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related_parts, select_related
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)
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table = model_cls.__table__
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column = model_cls.__table__.columns[field_name]
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else:
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op = "exact"
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column = self.table.columns[key]
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table = self.table
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value, has_escaped_character = self._escape_characters_in_clause(op, value)
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if isinstance(value, orm.Model):
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value = value.pk
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op_attr = FILTER_OPERATORS[op]
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clause = getattr(column, op_attr)(value)
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clause = self._compile_clause(
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clause,
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column,
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table,
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table_prefix,
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modifiers={"escape": "\\" if has_escaped_character else None},
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)
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filter_clauses.append(clause)
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return self.__class__(
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model_cls=self.model_cls,
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filter_clauses=filter_clauses,
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select_related=select_related,
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limit_count=self.limit_count,
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offset=self.query_offset,
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)
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def select_related(self, related: Union[List, Tuple, str]) -> "QuerySet":
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if not isinstance(related, (list, tuple)):
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related = [related]
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related = list(self._select_related) + related
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return self.__class__(
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model_cls=self.model_cls,
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filter_clauses=self.filter_clauses,
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select_related=related,
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limit_count=self.limit_count,
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offset=self.query_offset,
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)
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async def exists(self) -> bool:
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expr = self.build_select_expression()
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expr = sqlalchemy.exists(expr).select()
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return await self.database.fetch_val(expr)
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async def count(self) -> int:
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expr = self.build_select_expression().alias("subquery_for_count")
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expr = sqlalchemy.func.count().select().select_from(expr)
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return await self.database.fetch_val(expr)
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def limit(self, limit_count: int) -> "QuerySet":
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return self.__class__(
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model_cls=self.model_cls,
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filter_clauses=self.filter_clauses,
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select_related=self._select_related,
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limit_count=limit_count,
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offset=self.query_offset,
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)
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def offset(self, offset: int) -> "QuerySet":
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return self.__class__(
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model_cls=self.model_cls,
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filter_clauses=self.filter_clauses,
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select_related=self._select_related,
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limit_count=self.limit_count,
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offset=offset,
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)
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async def first(self, **kwargs: Any) -> "Model":
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if kwargs:
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return await self.filter(**kwargs).first()
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rows = await self.limit(1).all()
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if rows:
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return rows[0]
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async def get(self, **kwargs: Any) -> "Model":
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if kwargs:
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return await self.filter(**kwargs).get()
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expr = self.build_select_expression().limit(2)
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rows = await self.database.fetch_all(expr)
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if not rows:
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raise NoMatch()
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if len(rows) > 1:
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raise MultipleMatches()
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return self.model_cls.from_row(rows[0], select_related=self._select_related)
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async def all(self, **kwargs: Any) -> List["Model"]: # noqa: A003
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if kwargs:
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return await self.filter(**kwargs).all()
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expr = self.build_select_expression()
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rows = await self.database.fetch_all(expr)
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result_rows = [
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self.model_cls.from_row(row, select_related=self._select_related)
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for row in rows
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]
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result_rows = self.model_cls.merge_instances_list(result_rows)
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return result_rows
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async def create(self, **kwargs: Any) -> "Model":
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new_kwargs = dict(**kwargs)
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# Remove primary key when None to prevent not null constraint in postgresql.
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pkname = self.model_cls.__pkname__
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pk = self.model_cls.__model_fields__[pkname]
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if (
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pkname in new_kwargs
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and new_kwargs.get(pkname) is None
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and (pk.nullable or pk.autoincrement)
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):
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del new_kwargs[pkname]
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# substitute related models with their pk
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for field in self.model_cls._extract_related_names():
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if field in new_kwargs and new_kwargs.get(field) is not None:
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new_kwargs[field] = getattr(
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new_kwargs.get(field),
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self.model_cls.__model_fields__[field].to.__pkname__,
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)
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# Build the insert expression.
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expr = self.table.insert()
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expr = expr.values(**new_kwargs)
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# Execute the insert, and return a new model instance.
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instance = self.model_cls(**kwargs)
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instance.pk = await self.database.execute(expr)
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return instance
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