alamb commented on code in PR #9743: URL: https://github.com/apache/arrow-datafusion/pull/9743#discussion_r1544417930
########## datafusion/functions/src/core/named_struct.rs: ########## @@ -0,0 +1,196 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +use arrow::array::StructArray; +use arrow::datatypes::{DataType, Field, Fields}; +use datafusion_common::{exec_err, internal_err, Result, ScalarValue}; +use datafusion_expr::{ColumnarValue, Expr, ExprSchemable}; +use datafusion_expr::{ScalarUDFImpl, Signature, Volatility}; +use std::any::Any; +use std::sync::Arc; + +/// put values in a struct array. +fn named_struct_expr(args: &[ColumnarValue]) -> Result<ColumnarValue> { + // do not accept 0 arguments. + if args.is_empty() { + return exec_err!("named_struct requires at least one pair of arguments, got 0 instead"); + } + + if args.len() % 2 != 0 { + return exec_err!("named_struct requires an even number of arguments, got {} instead", args.len()); + } + + let (names, values): (Vec<_>, Vec<_>) = args + .chunks_exact(2) + .enumerate() + .map(|(i, chunk)| { + + let name_column = &chunk[0]; + + let name = match name_column { + ColumnarValue::Scalar(ScalarValue::Utf8(Some(name_scalar))) => name_scalar, + _ => return exec_err!("named_struct even arguments must be string literals, got {name_column:?} instead at position {}", i * 2) + }; + + Ok((name, chunk[1].clone())) + }) + .collect::<Result<Vec<_>>>()? + .into_iter() + .unzip(); + + let arrays = ColumnarValue::values_to_arrays(&values)?; + + let fields = names.into_iter() + .zip(arrays) + .map(|(name, value)| { + ( + Arc::new(Field::new( + name, + value.data_type().clone(), + true, + )), + value, + ) + }) + .collect::<Vec<_>>(); + + Ok(ColumnarValue::Array(Arc::new(StructArray::from(fields)))) +} + +#[derive(Debug)] +pub(super) struct NamedStructFunc { + signature: Signature, +} + +impl NamedStructFunc { + pub fn new() -> Self { + Self { + signature: Signature::variadic_any(Volatility::Immutable), + } + } +} + +impl ScalarUDFImpl for NamedStructFunc { + fn as_any(&self) -> &dyn Any { + self + } + + fn name(&self) -> &str { + "named_struct" + } + + fn signature(&self) -> &Signature { + &self.signature + } + + fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> { + internal_err!("named_struct: return_type called instead of return_type_from_exprs") + } + + fn return_type_from_exprs( + &self, + args: &[datafusion_expr::Expr], + schema: &dyn datafusion_common::ExprSchema, + _arg_types: &[DataType], + ) -> Result<DataType> { + // do not accept 0 arguments. + if args.is_empty() { + return exec_err!("named_struct requires at least one pair of arguments, got 0 instead"); + } + + if args.len() % 2 != 0 { + return exec_err!("named_struct requires an even number of arguments, got {} instead", args.len()); + } + + let return_fields = args + .chunks_exact(2) + .enumerate() + .map(|(i, chunk)| { + let name = &chunk[0]; + let value = &chunk[1]; + + if let Expr::Literal(ScalarValue::Utf8(Some(name))) = name { + Ok(Field::new(name, value.get_type(schema)?, true)) + } else { + exec_err!("named_struct even arguments must be string literals, got {name} instead at position {}", i * 2) + } + }) + .collect::<Result<Vec<Field>>>()?; + Ok(DataType::Struct(Fields::from(return_fields))) + } + + fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> { + named_struct_expr(args) + } +} + +#[cfg(test)] +mod tests { + use super::*; + use arrow::array::Int64Array; + use datafusion_common::cast::as_struct_array; + use datafusion_common::ScalarValue; + + #[test] + fn test_named_struct() { + // named_struct("first", 1, "second", 2, "third", 3) = {"first": 1, "second": 2, "third": 3} Review Comment: Since I was pushing commits to this PR anyways as the CI failed, I also did this suggestion in f35cddc12 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
