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query

Query

Source code in ormar/queryset/queries/query.py
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class Query:
    def __init__(  # noqa CFQ002
        self,
        model_cls: Type["Model"],
        filter_clauses: List[FilterAction],
        exclude_clauses: List[FilterAction],
        select_related: List,
        limit_count: Optional[int],
        offset: Optional[int],
        excludable: "ExcludableItems",
        order_bys: Optional[List["OrderAction"]],
        limit_raw_sql: bool,
    ) -> None:
        self.query_offset = offset
        self.limit_count = limit_count
        self._select_related = select_related[:]
        self.filter_clauses = filter_clauses[:]
        self.exclude_clauses = exclude_clauses[:]
        self.excludable = excludable

        self.model_cls = model_cls
        self.table = self.model_cls.Meta.table

        self.used_aliases: List[str] = []

        self.select_from: Union[Join, Table, List[str]] = []
        self.columns = [sqlalchemy.Column]
        self.order_columns = order_bys
        self.sorted_orders: Dict[OrderAction, text] = {}
        self._init_sorted_orders()

        self.limit_raw_sql = limit_raw_sql

    def _init_sorted_orders(self) -> None:
        """
        Initialize empty order_by dict to be populated later during the query call
        """
        if self.order_columns:
            for clause in self.order_columns:
                self.sorted_orders[clause] = None

    def apply_order_bys_for_primary_model(self) -> None:  # noqa: CCR001
        """
        Applies order_by queries on main model when it's used as a subquery.
        That way the subquery with limit and offset only on main model has proper
        sorting applied and correct models are fetched.
        """
        current_table_sorted = False
        if self.order_columns:
            for clause in self.order_columns:
                if clause.is_source_model_order:
                    current_table_sorted = True
                    self.sorted_orders[clause] = clause.get_text_clause()

        if not current_table_sorted:
            self._apply_default_model_sorting()

    def _apply_default_model_sorting(self) -> None:
        """
        Applies orders_by from model Meta class (if provided), if it was not provided
        it was filled by metaclass so it's always there and falls back to pk column
        """
        for order_by in self.model_cls.Meta.orders_by:
            clause = ormar.OrderAction(order_str=order_by, model_cls=self.model_cls)
            self.sorted_orders[clause] = clause.get_text_clause()

    def _pagination_query_required(self) -> bool:
        """
        Checks if limit or offset are set, the flag limit_sql_raw is not set
        and query has select_related applied. Otherwise we can limit/offset normally
        at the end of whole query.

        :return: result of the check
        :rtype: bool
        """
        return bool(
            (self.limit_count or self.query_offset)
            and not self.limit_raw_sql
            and self._select_related
        )

    def build_select_expression(self) -> Tuple[sqlalchemy.sql.select, List[str]]:
        """
        Main entry point from outside (after proper initialization).

        Extracts columns list to fetch,
        construct all required joins for select related,
        then applies all conditional and sort clauses.

        Returns ready to run query with all joins and clauses.

        :return: ready to run query with all joins and clauses.
        :rtype: sqlalchemy.sql.selectable.Select
        """
        self_related_fields = self.model_cls.own_table_columns(
            model=self.model_cls, excludable=self.excludable, use_alias=True
        )
        self.columns = self.model_cls.Meta.alias_manager.prefixed_columns(
            "", self.table, self_related_fields
        )
        self.apply_order_bys_for_primary_model()
        self.select_from = self.table

        related_models = group_related_list(self._select_related)

        for related in related_models:
            remainder = None
            if isinstance(related_models, dict) and related_models[related]:
                remainder = related_models[related]
            sql_join = SqlJoin(
                used_aliases=self.used_aliases,
                select_from=self.select_from,
                columns=self.columns,
                excludable=self.excludable,
                order_columns=self.order_columns,
                sorted_orders=self.sorted_orders,
                main_model=self.model_cls,
                relation_name=related,
                relation_str=related,
                related_models=remainder,
            )

            (
                self.used_aliases,
                self.select_from,
                self.columns,
                self.sorted_orders,
            ) = sql_join.build_join()

        if self._pagination_query_required():
            limit_qry, on_clause = self._build_pagination_condition()
            self.select_from = sqlalchemy.sql.join(
                self.select_from, limit_qry, on_clause
            )

        expr = sqlalchemy.sql.select(self.columns)
        expr = expr.select_from(self.select_from)

        expr = self._apply_expression_modifiers(expr)

        # print("\n", expr.compile(compile_kwargs={"literal_binds": True}))
        self._reset_query_parameters()

        return expr

    def _build_pagination_condition(
        self,
    ) -> Tuple[
        sqlalchemy.sql.expression.TextClause, sqlalchemy.sql.expression.TextClause
    ]:
        """
        In order to apply limit and offset on main table in join only
        (otherwise you can get only partially constructed main model
        if number of children exceeds the applied limit and select_related is used)

        Used also to change first and get() without argument behaviour.
        Needed only if limit or offset are set, the flag limit_sql_raw is not set
        and query has select_related applied. Otherwise we can limit/offset normally
        at the end of whole query.

        The condition is added to filters to filter out desired number of main model
        primary key values. Whole query is used to determine the values.
        """
        pk_alias = self.model_cls.get_column_alias(self.model_cls.Meta.pkname)
        pk_aliased_name = f"{self.table.name}.{pk_alias}"
        qry_text = sqlalchemy.text(f"{pk_aliased_name}")
        maxes = {}
        for order in list(self.sorted_orders.keys()):
            if order is not None and order.get_field_name_text() != pk_aliased_name:
                aliased_col = order.get_field_name_text()
                # maxes[aliased_col] = order.get_text_clause()
                maxes[aliased_col] = order.get_min_or_max()
            elif order.get_field_name_text() == pk_aliased_name:
                maxes[pk_aliased_name] = order.get_text_clause()

        limit_qry = sqlalchemy.sql.select([qry_text])
        limit_qry = limit_qry.select_from(self.select_from)
        limit_qry = FilterQuery(filter_clauses=self.filter_clauses).apply(limit_qry)
        limit_qry = FilterQuery(
            filter_clauses=self.exclude_clauses, exclude=True
        ).apply(limit_qry)
        limit_qry = limit_qry.group_by(qry_text)
        for order_by in maxes.values():
            limit_qry = limit_qry.order_by(order_by)
        limit_qry = LimitQuery(limit_count=self.limit_count).apply(limit_qry)
        limit_qry = OffsetQuery(query_offset=self.query_offset).apply(limit_qry)
        limit_qry = limit_qry.alias("limit_query")
        on_clause = sqlalchemy.text(
            f"limit_query.{pk_alias}={self.table.name}.{pk_alias}"
        )
        return limit_qry, on_clause

    def _apply_expression_modifiers(
        self, expr: sqlalchemy.sql.select
    ) -> sqlalchemy.sql.select:
        """
        Receives the select query (might be join) and applies:
        * Filter clauses
        * Exclude filter clauses
        * Limit clauses
        * Offset clauses
        * Order by clauses

        Returns complete ready to run query.

        :param expr: select expression before clauses
        :type expr: sqlalchemy.sql.selectable.Select
        :return: expresion with all present clauses applied
        :rtype: sqlalchemy.sql.selectable.Select
        """
        expr = FilterQuery(filter_clauses=self.filter_clauses).apply(expr)
        expr = FilterQuery(filter_clauses=self.exclude_clauses, exclude=True).apply(
            expr
        )
        if not self._pagination_query_required():
            expr = LimitQuery(limit_count=self.limit_count).apply(expr)
            expr = OffsetQuery(query_offset=self.query_offset).apply(expr)
        expr = OrderQuery(sorted_orders=self.sorted_orders).apply(expr)
        return expr

    def _reset_query_parameters(self) -> None:
        """
        Although it should be created each time before the call we reset the key params
        anyway.
        """
        self.select_from = []
        self.columns = []
        self.used_aliases = []

apply_order_bys_for_primary_model()

Applies order_by queries on main model when it's used as a subquery. That way the subquery with limit and offset only on main model has proper sorting applied and correct models are fetched.

Source code in ormar/queryset/queries/query.py
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def apply_order_bys_for_primary_model(self) -> None:  # noqa: CCR001
    """
    Applies order_by queries on main model when it's used as a subquery.
    That way the subquery with limit and offset only on main model has proper
    sorting applied and correct models are fetched.
    """
    current_table_sorted = False
    if self.order_columns:
        for clause in self.order_columns:
            if clause.is_source_model_order:
                current_table_sorted = True
                self.sorted_orders[clause] = clause.get_text_clause()

    if not current_table_sorted:
        self._apply_default_model_sorting()

build_select_expression()

Main entry point from outside (after proper initialization).

Extracts columns list to fetch, construct all required joins for select related, then applies all conditional and sort clauses.

Returns ready to run query with all joins and clauses.

Returns:

Type Description
sqlalchemy.sql.selectable.Select

ready to run query with all joins and clauses.

Source code in ormar/queryset/queries/query.py
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def build_select_expression(self) -> Tuple[sqlalchemy.sql.select, List[str]]:
    """
    Main entry point from outside (after proper initialization).

    Extracts columns list to fetch,
    construct all required joins for select related,
    then applies all conditional and sort clauses.

    Returns ready to run query with all joins and clauses.

    :return: ready to run query with all joins and clauses.
    :rtype: sqlalchemy.sql.selectable.Select
    """
    self_related_fields = self.model_cls.own_table_columns(
        model=self.model_cls, excludable=self.excludable, use_alias=True
    )
    self.columns = self.model_cls.Meta.alias_manager.prefixed_columns(
        "", self.table, self_related_fields
    )
    self.apply_order_bys_for_primary_model()
    self.select_from = self.table

    related_models = group_related_list(self._select_related)

    for related in related_models:
        remainder = None
        if isinstance(related_models, dict) and related_models[related]:
            remainder = related_models[related]
        sql_join = SqlJoin(
            used_aliases=self.used_aliases,
            select_from=self.select_from,
            columns=self.columns,
            excludable=self.excludable,
            order_columns=self.order_columns,
            sorted_orders=self.sorted_orders,
            main_model=self.model_cls,
            relation_name=related,
            relation_str=related,
            related_models=remainder,
        )

        (
            self.used_aliases,
            self.select_from,
            self.columns,
            self.sorted_orders,
        ) = sql_join.build_join()

    if self._pagination_query_required():
        limit_qry, on_clause = self._build_pagination_condition()
        self.select_from = sqlalchemy.sql.join(
            self.select_from, limit_qry, on_clause
        )

    expr = sqlalchemy.sql.select(self.columns)
    expr = expr.select_from(self.select_from)

    expr = self._apply_expression_modifiers(expr)

    # print("\n", expr.compile(compile_kwargs={"literal_binds": True}))
    self._reset_query_parameters()

    return expr