3.6 KiB
queryset.query
Query Objects
class Query()
_init_sorted_orders
| _init_sorted_orders() -> None
Initialize empty order_by dict to be populated later during the query call
prefixed_pk_name
| @property
| prefixed_pk_name() -> str
Shortcut for extracting prefixed with alias primary key column name from main model
Returns:
(str): alias of pk column prefix with table name.
alias
| alias(name: str) -> str
Shortcut to extracting column alias from given master model.
Arguments:
name (str): name of column
Returns:
(str): alias of given column name
apply_order_bys_for_primary_model
| apply_order_bys_for_primary_model() -> None
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.
_pagination_query_required
| _pagination_query_required() -> 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.
Returns:
(bool): result of the check
build_select_expression
| build_select_expression() -> 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.
Returns:
(sqlalchemy.sql.selectable.Select): ready to run query with all joins and clauses.
_build_pagination_subquery
| _build_pagination_subquery() -> sqlalchemy.sql.select
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.
Returns:
(sqlalchemy.sql.select): constructed subquery on main table with limit, offset and order applied
_apply_expression_modifiers
| _apply_expression_modifiers(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.
Arguments:
expr (sqlalchemy.sql.selectable.Select): select expression before clauses
Returns:
(sqlalchemy.sql.selectable.Select): expresion with all present clauses applied
_reset_query_parameters
| _reset_query_parameters() -> None
Although it should be created each time before the call we reset the key params anyway.