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fix: correctly specify the nullability of map_values return type #15901

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Merged
merged 2 commits into from
May 1, 2025
Merged

fix: correctly specify the nullability of map_values return type #15901

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a9b9923
fix: correctly specify the nullability of `map_values` return type
rluvaton Apr 30, 2025
198ea09
Merge remote-tracking branch 'apache/main' into fix-return-type
alamb Apr 30, 2025
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158 changes: 148 additions & 10 deletions datafusion/functions-nested/src/map_values.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,15 +19,16 @@

use crate::utils::{get_map_entry_field, make_scalar_function};
use arrow::array::{Array, ArrayRef, ListArray};
use arrow::datatypes::{DataType, Field};
use arrow::datatypes::{DataType, Field, FieldRef};
use datafusion_common::utils::take_function_args;
use datafusion_common::{cast::as_map_array, exec_err, Result};
use datafusion_common::{cast::as_map_array, exec_err, internal_err, Result};
use datafusion_expr::{
ArrayFunctionSignature, ColumnarValue, Documentation, ScalarUDFImpl, Signature,
TypeSignature, Volatility,
};
use datafusion_macros::user_doc;
use std::any::Any;
use std::ops::Deref;
use std::sync::Arc;

make_udf_expr_and_func!(
Expand Down Expand Up @@ -91,13 +92,22 @@ impl ScalarUDFImpl for MapValuesFunc {
&self.signature
}

fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
let [map_type] = take_function_args(self.name(), arg_types)?;
let map_fields = get_map_entry_field(map_type)?;
Ok(DataType::List(Arc::new(Field::new_list_field(
map_fields.last().unwrap().data_type().clone(),
true,
))))
fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> {
internal_err!("return_field_from_args should be used instead")
}

fn return_field_from_args(
&self,
args: datafusion_expr::ReturnFieldArgs,
) -> Result<Field> {
let [map_type] = take_function_args(self.name(), args.arg_fields)?;

Ok(Field::new(
self.name(),
DataType::List(get_map_values_field_as_list_field(map_type.data_type())?),
// Nullable if the map is nullable
args.arg_fields.iter().any(|x| x.is_nullable()),
))
}

fn invoke_with_args(
Expand All @@ -121,9 +131,137 @@ fn map_values_inner(args: &[ArrayRef]) -> Result<ArrayRef> {
};

Ok(Arc::new(ListArray::new(
Arc::new(Field::new_list_field(map_array.value_type().clone(), true)),
get_map_values_field_as_list_field(map_arg.data_type())?,
map_array.offsets().clone(),
Arc::clone(map_array.values()),
map_array.nulls().cloned(),
)))
}

fn get_map_values_field_as_list_field(map_type: &DataType) -> Result<FieldRef> {
let map_fields = get_map_entry_field(map_type)?;

let values_field = map_fields
.last()
.unwrap()
.deref()
.clone()
.with_name(Field::LIST_FIELD_DEFAULT_NAME);

Ok(Arc::new(values_field))
}

#[cfg(test)]
mod tests {
use crate::map_values::MapValuesFunc;
use arrow::datatypes::{DataType, Field};
use datafusion_common::ScalarValue;
use datafusion_expr::ScalarUDFImpl;
use std::sync::Arc;

#[test]
fn return_type_field() {
fn get_map_field(
is_map_nullable: bool,
is_keys_nullable: bool,
is_values_nullable: bool,
) -> Field {
Field::new_map(
"something",
"entries",
Arc::new(Field::new("keys", DataType::Utf8, is_keys_nullable)),
Arc::new(Field::new(
"values",
DataType::LargeUtf8,
is_values_nullable,
)),
false,
is_map_nullable,
)
}

fn get_list_field(
name: &str,
is_list_nullable: bool,
list_item_type: DataType,
is_list_items_nullable: bool,
) -> Field {
Field::new_list(
name,
Arc::new(Field::new_list_field(
list_item_type,
is_list_items_nullable,
)),
is_list_nullable,
)
}

fn get_return_field(field: Field) -> Field {
let func = MapValuesFunc::new();
let args = datafusion_expr::ReturnFieldArgs {
arg_fields: &[field],
scalar_arguments: &[None::<&ScalarValue>],
};

func.return_field_from_args(args).unwrap()
}

// Test cases:
//
// | Input Map || Expected Output |
// | ------------------------------------------------------ || ----------------------------------------------------- |
// | map nullable | map keys nullable | map values nullable || expected list nullable | expected list items nullable |
// | ------------ | ----------------- | ------------------- || ---------------------- | ---------------------------- |
// | false | false | false || false | false |
// | false | false | true || false | true |
// | false | true | false || false | false |
// | false | true | true || false | true |
// | true | false | false || true | false |
// | true | false | true || true | true |
// | true | true | false || true | false |
// | true | true | true || true | true |
//
// ---------------
// We added the key nullability to show that it does not affect the nullability of the list or the list items.

assert_eq!(
get_return_field(get_map_field(false, false, false)),
get_list_field("map_values", false, DataType::LargeUtf8, false)
);

assert_eq!(
get_return_field(get_map_field(false, false, true)),
get_list_field("map_values", false, DataType::LargeUtf8, true)
);

assert_eq!(
get_return_field(get_map_field(false, true, false)),
get_list_field("map_values", false, DataType::LargeUtf8, false)
);

assert_eq!(
get_return_field(get_map_field(false, true, true)),
get_list_field("map_values", false, DataType::LargeUtf8, true)
);

assert_eq!(
get_return_field(get_map_field(true, false, false)),
get_list_field("map_values", true, DataType::LargeUtf8, false)
);

assert_eq!(
get_return_field(get_map_field(true, false, true)),
get_list_field("map_values", true, DataType::LargeUtf8, true)
);

assert_eq!(
get_return_field(get_map_field(true, true, false)),
get_list_field("map_values", true, DataType::LargeUtf8, false)
);

assert_eq!(
get_return_field(get_map_field(true, true, true)),
get_list_field("map_values", true, DataType::LargeUtf8, true)
);
}
}