kosiew commented on code in PR #1221:
URL:
https://github.com/apache/datafusion-python/pull/1221#discussion_r2347846358
##########
python/datafusion/expr.py:
##########
@@ -212,32 +224,119 @@
"WindowExpr",
"WindowFrame",
"WindowFrameBound",
+ "ensure_expr",
+ "ensure_expr_list",
]
+def ensure_expr(value: _typing.Union[Expr, Any]) -> expr_internal.Expr:
+ """Return the internal expression from ``Expr`` or raise ``TypeError``.
+
+ This helper rejects plain strings and other non-:class:`Expr` values so
+ higher level APIs consistently require explicit :func:`~datafusion.col` or
+ :func:`~datafusion.lit` expressions.
+
+ Args:
+ value: Candidate expression or other object.
+
+ Returns:
+ The internal expression representation.
+
+ Raises:
+ TypeError: If ``value`` is not an instance of :class:`Expr`.
+ """
+ if not isinstance(value, Expr):
+ raise TypeError(EXPR_TYPE_ERROR)
+ return value.expr
+
+
+def ensure_expr_list(
+ exprs: Iterable[_typing.Union[Expr, Iterable[Expr]]],
+) -> list[expr_internal.Expr]:
+ """Flatten an iterable of expressions, validating each via ``ensure_expr``.
+
+ Args:
+ exprs: Possibly nested iterable containing expressions.
+
+ Returns:
+ A flat list of raw expressions.
+
+ Raises:
+ TypeError: If any item is not an instance of :class:`Expr`.
+ """
+
+ def _iter(
+ items: Iterable[_typing.Union[Expr, Iterable[Expr]]],
+ ) -> Iterable[expr_internal.Expr]:
+ for expr in items:
+ if isinstance(expr, Iterable) and not isinstance(
+ expr, (Expr, str, bytes, bytearray)
+ ):
+ # Treat string-like objects as atomic to surface standard
errors
+ yield from _iter(expr)
+ else:
+ yield ensure_expr(expr)
+
+ return list(_iter(exprs))
+
+
+def _to_raw_expr(value: _typing.Union[Expr, str]) -> expr_internal.Expr:
+ """Convert a Python expression or column name to its raw variant.
+
+ Args:
+ value: Candidate expression or column name.
+
+ Returns:
+ The internal :class:`~datafusion._internal.expr.Expr` representation.
+
+ Raises:
+ TypeError: If ``value`` is neither an :class:`Expr` nor ``str``.
+ """
+ if isinstance(value, str):
+ return Expr.column(value).expr
+ if isinstance(value, Expr):
+ return value.expr
+ error = (
+ "Expected Expr or column name, found:"
+ f" {type(value).__name__}. {EXPR_TYPE_ERROR}."
+ )
+ raise TypeError(error)
+
+
def expr_list_to_raw_expr_list(
- expr_list: Optional[list[Expr] | Expr],
+ expr_list: Optional[_typing.Union[Sequence[_typing.Union[Expr, str]],
Expr, str]],
Review Comment:
I will amend this.
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