Function _get_crud_params

lib/sqlalchemy/sql/crud.py:117–456

create a set of tuples representing column/string pairs for use in an INSERT or UPDATE statement. Also generates the Compiled object's postfetch, prefetch, and returning column collections, used for default handling and ultimately populating the CursorResult's prefetch_cols() and po

(
    compiler: SQLCompiler,
    stmt: ValuesBase,
    compile_state: DMLState,
    toplevel: bool,
    **kw: Any,
)

def _get_crud_params(
    compiler: SQLCompiler,
    stmt: ValuesBase,
    compile_state: DMLState,
    toplevel: bool,
    **kw: Any,
) -> _CrudParams:
    """create a set of tuples representing column/string pairs for use
    in an INSERT or UPDATE statement.

    Also generates the Compiled object's postfetch, prefetch, and
    returning column collections, used for default handling and ultimately
    populating the CursorResult's prefetch_cols() and postfetch_cols()
    collections.

    """

    # note: the _get_crud_params() system was written with the notion in mind
    # that INSERT, UPDATE, DELETE are always the top level statement and
    # that there is only one of them.  With the addition of CTEs that can
    # make use of DML, this assumption is no longer accurate; the DML
    # statement is not necessarily the top-level "row returning" thing
    # and it is also theoretically possible (fortunately nobody has asked yet)
    # to have a single statement with multiple DMLs inside of it via CTEs.

    # the current _get_crud_params() design doesn't accommodate these cases
    # right now.  It "just works" for a CTE that has a single DML inside of
    # it, and for a CTE with multiple DML, it's not clear what would happen.

    # overall, the "compiler.XYZ" collections here would need to be in a
    # per-DML structure of some kind, and DefaultDialect would need to
    # navigate these collections on a per-statement basis, with additional
    # emphasis on the "toplevel returning data" statement.  However we
    # still need to run through _get_crud_params() for all DML as we have
    # Python / SQL generated column defaults that need to be rendered.

    # if there is user need for this kind of thing, it's likely a post 2.0
    # kind of change as it would require deep changes to DefaultDialect
    # as well as here.

    compiler.postfetch = []
    compiler.insert_prefetch = []
    compiler.update_prefetch = []
    compiler.implicit_returning = []

    visiting_cte = kw.get("visiting_cte", None)
    if visiting_cte is not None:
        # for insert -> CTE -> insert, don't populate an incoming
        # _crud_accumulate_bind_names collection; the INSERT we process here
        # will not be inline within the VALUES of the enclosing INSERT as the
        # CTE is placed on the outside.  See issue #9173
        kw.pop("accumulate_bind_names", None)
    assert (
        "accumulate_bind_names" not in kw
    ), "Don't know how to handle insert within insert without a CTE"

    bindmarkers: MutableMapping[ColumnElement[Any], DMLTargetCopy[Any]] = {}
    kw["bindmarkers"] = bindmarkers