fix: update arrow_cast function to accept string type for data_type parameter

Author: kosiew

python/datafusion/functions.py

@@ -17,7 +17,6 @@
 """User functions for operating on :py:class:`~datafusion.expr.Expr`."""
 
 from __future__ import annotations
-
 from datafusion._internal import functions as f
 from datafusion.expr import (
     CaseBuilder,
@@ -1100,9 +1099,9 @@ def arrow_typeof(arg: Expr) -> Expr:
     return Expr(f.arrow_typeof(arg.expr))
 
 
-def arrow_cast(expr: Expr, data_type: Expr) -> Expr:
+def arrow_cast(expr: Expr, data_type: str) -> Expr:
     """Casts an expression to a specified data type."""
-    return Expr(f.arrow_cast(expr.expr, data_type.expr))
+    return Expr(f.arrow_cast(expr.expr, literal(data_type).expr))
 
 
 def random() -> Expr:

python/tests/test_functions.py

@@ -907,8 +907,8 @@ def test_temporal_functions(df):
 
 def test_arrow_cast(df):
     df = df.select(
-        f.arrow_cast(column("a"), literal("Float64")).alias("a_as_float"),
-        f.arrow_cast(column("a"), literal("Int32")).alias("a_as_int"),
+        f.arrow_cast(column("a"), "Float64").alias("a_as_float"),
+        f.arrow_cast(column("a"), "Int32").alias("a_as_int"),
     )
     result = df.collect()
     assert len(result) == 1