diff --git a/arrow-cast/src/cast.rs b/arrow-cast/src/cast.rs index 0775392b7d6..92b9071a675 100644 --- a/arrow-cast/src/cast.rs +++ b/arrow-cast/src/cast.rs @@ -160,11 +160,13 @@ pub fn can_cast_types(from_type: &DataType, to_type: &DataType) -> bool { (Decimal128(_, _) | Decimal256(_, _), Utf8 | LargeUtf8) => true, // Utf8 to decimal (Utf8 | LargeUtf8, Decimal128(_, _) | Decimal256(_, _)) => true, - (Struct(from_fields), Struct(to_fields)) => { - from_fields.len() == to_fields.len() && - from_fields.iter().zip(to_fields.iter()).all(|(f1, f2)| { - can_cast_types(f1.data_type(), f2.data_type()) - }) + (Struct(from_fields), Struct(to_fields)) => { + from_fields.len() == to_fields.len() && + from_fields.iter().zip(to_fields.iter()).all(|(f1, f2)| { + // Assume that nullability between two structs are compatible, if not, + // cast kernel will return error. + can_cast_types(f1.data_type(), f2.data_type()) + }) } (Struct(_), _) => false, (_, Struct(_)) => false, @@ -1152,7 +1154,7 @@ pub fn cast_with_options( .zip(to_fields.iter()) .map(|(l, field)| cast_with_options(l, field.data_type(), cast_options)) .collect::, ArrowError>>()?; - let array = StructArray::new(to_fields.clone(), fields, array.nulls().cloned()); + let array = StructArray::try_new(to_fields.clone(), fields, array.nulls().cloned())?; Ok(Arc::new(array) as ArrayRef) } (Struct(_), _) => Err(ArrowError::CastError( @@ -9525,4 +9527,77 @@ mod tests { result.unwrap_err().to_string() ); } + + #[test] + fn test_cast_struct_to_struct_nullability() { + let boolean = Arc::new(BooleanArray::from(vec![false, false, true, true])); + let int = Arc::new(Int32Array::from(vec![Some(42), None, Some(19), None])); + let struct_array = StructArray::from(vec![ + ( + Arc::new(Field::new("b", DataType::Boolean, false)), + boolean.clone() as ArrayRef, + ), + ( + Arc::new(Field::new("c", DataType::Int32, true)), + int.clone() as ArrayRef, + ), + ]); + + // okay: nullable to nullable + let to_type = DataType::Struct( + vec![ + Field::new("a", DataType::Utf8, false), + Field::new("b", DataType::Utf8, true), + ] + .into(), + ); + cast(&struct_array, &to_type).expect("Cast nullable to nullable struct field should work"); + + // error: nullable to non-nullable + let to_type = DataType::Struct( + vec![ + Field::new("a", DataType::Utf8, false), + Field::new("b", DataType::Utf8, false), + ] + .into(), + ); + cast(&struct_array, &to_type) + .expect_err("Cast nullable to non-nullable struct field should fail"); + + let boolean = Arc::new(BooleanArray::from(vec![false, false, true, true])); + let int = Arc::new(Int32Array::from(vec![i32::MAX, 25, 1, 100])); + let struct_array = StructArray::from(vec![ + ( + Arc::new(Field::new("b", DataType::Boolean, false)), + boolean.clone() as ArrayRef, + ), + ( + Arc::new(Field::new("c", DataType::Int32, false)), + int.clone() as ArrayRef, + ), + ]); + + // okay: non-nullable to non-nullable + let to_type = DataType::Struct( + vec![ + Field::new("a", DataType::Utf8, false), + Field::new("b", DataType::Utf8, false), + ] + .into(), + ); + cast(&struct_array, &to_type) + .expect("Cast non-nullable to non-nullable struct field should work"); + + // err: non-nullable to non-nullable but overflowing return null during casting + let to_type = DataType::Struct( + vec![ + Field::new("a", DataType::Utf8, false), + Field::new("b", DataType::Int8, false), + ] + .into(), + ); + cast(&struct_array, &to_type).expect_err( + "Cast non-nullable to non-nullable struct field returning null should fail", + ); + } }