feat: accept pyarrow DataType in arrow_try_cast

Mirrors arrow_cast: arrow_try_cast now accepts `pa.DataType` in addition
to `str` and `Expr`. Adds `Expr.try_cast(pa.DataType)` PyO3 binding for
the pyarrow-type routing path.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: timsaucer

crates/core/src/expr.rs

@@ -358,6 +358,11 @@ impl PyExpr {
         expr.into()
     }
 
+    pub fn try_cast(&self, to: PyArrowType<DataType>) -> PyExpr {
+        let expr = Expr::TryCast(TryCast::new(Box::new(self.expr.clone()), to.0));
+        expr.into()
+    }
+
     #[pyo3(signature = (low, high, negated=false))]
     pub fn between(&self, low: PyExpr, high: PyExpr, negated: bool) -> PyExpr {
         let expr = Expr::Between(Between::new(

python/datafusion/expr.py

@@ -894,6 +894,28 @@ def cast(self, to: pa.DataType[Any] | type) -> Expr:
 
         return Expr(self.expr.cast(to))
 
+    def try_cast(self, to: pa.DataType[Any] | type) -> Expr:
+        """Cast to a new data type, returning NULL on failure.
+
+        Like :py:meth:`cast` but produces NULL instead of erroring when the
+        cast cannot be performed for a given row.
+
+        Examples:
+            >>> ctx = dfn.SessionContext()
+            >>> df = ctx.from_pydict({"a": ["oops"]})
+            >>> result = df.select(col("a").try_cast(pa.float64()).alias("c"))
+            >>> result.collect_column("c")[0].as_py() is None
+            True
+        """
+        if not isinstance(to, pa.DataType):
+            try:
+                to = self._to_pyarrow_types[to]
+            except KeyError as err:
+                error_msg = "Expected instance of pyarrow.DataType or builtins.type"
+                raise TypeError(error_msg) from err
+
+        return Expr(self.expr.try_cast(to))
+
     def between(self, low: Any, high: Any, negated: bool = False) -> Expr:
         """Returns ``True`` if this expression is between a given range.
 

python/datafusion/functions.py

@@ -2934,12 +2934,13 @@ def arrow_cast(expr: Expr, data_type: Expr | str | pa.DataType) -> Expr:
     return Expr(f.arrow_cast(expr.expr, data_type.expr))
 
 
-def arrow_try_cast(expr: Expr, data_type: Expr | str) -> Expr:
+def arrow_try_cast(expr: Expr, data_type: Expr | str | pa.DataType) -> Expr:
     """Casts an expression to a specified data type, returning NULL on failure.
 
     Like :py:func:`arrow_cast` but produces NULL instead of erroring when the
     cast cannot be performed. The ``data_type`` may be a string in DataFusion
-    type syntax (for example ``"Float64"``) or an ``Expr`` of string type.
+    type syntax (for example ``"Float64"``), a ``pyarrow.DataType``, or an
+    ``Expr`` of string type.
 
     Examples:
         >>> ctx = dfn.SessionContext()
@@ -2949,7 +2950,17 @@ def arrow_try_cast(expr: Expr, data_type: Expr | str) -> Expr:
         ... )
         >>> result.collect_column("c")[0].as_py() is None
         True
+
+        >>> result = df.select(
+        ...     dfn.functions.arrow_try_cast(
+        ...         dfn.col("a"), data_type=pa.float64()
+        ...     ).alias("c")
+        ... )
+        >>> result.collect_column("c")[0].as_py() is None
+        True
     """
+    if isinstance(data_type, pa.DataType):
+        return expr.try_cast(data_type)
     if isinstance(data_type, str):
         data_type = Expr.string_literal(data_type)
     return Expr(f.arrow_try_cast(expr.expr, data_type.expr))