CuteChuanChuan commented on code in PR #20412: URL: https://github.com/apache/datafusion/pull/20412#discussion_r2832196468
########## datafusion/spark/src/function/json/json_tuple.rs: ########## @@ -0,0 +1,255 @@ +// 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 std::any::Any; +use std::sync::Arc; + +use arrow::array::{ + Array, ArrayRef, NullBufferBuilder, StringArray, StringBuilder, StructArray, +}; +use arrow::datatypes::{DataType, Field, FieldRef, Fields}; +use datafusion_common::{Result, exec_err, internal_err}; +use datafusion_expr::{ + ColumnarValue, ReturnFieldArgs, ScalarFunctionArgs, ScalarUDFImpl, Signature, + Volatility, +}; + +/// Spark-compatible `json_tuple` expression +/// +/// <https://spark.apache.org/docs/latest/api/sql/index.html#json_tuple> +/// +/// Extracts top-level fields from a JSON string and returns them as a struct. +/// +/// `json_tuple(json_string, field1, field2, ...) -> Struct<c0: Utf8, c1: Utf8, ...>` +/// +/// - Returns NULL for each field that is missing from the JSON object +/// - Returns NULL for all fields if the input is NULL or not valid JSON +/// - Non-string JSON values are converted to their JSON string representation +/// - JSON `null` values are returned as NULL (not the string "null") +#[derive(Debug, PartialEq, Eq, Hash)] +pub struct JsonTuple { + signature: Signature, +} + +impl Default for JsonTuple { + fn default() -> Self { + Self::new() + } +} + +impl JsonTuple { + pub fn new() -> Self { + Self { + signature: Signature::variadic(vec![DataType::Utf8], Volatility::Immutable), + } + } +} + +impl ScalarUDFImpl for JsonTuple { + fn as_any(&self) -> &dyn Any { + self + } + + fn name(&self) -> &str { + "json_tuple" + } + + fn signature(&self) -> &Signature { + &self.signature + } + + 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: ReturnFieldArgs) -> Result<FieldRef> { + if args.arg_fields.len() < 2 { + return exec_err!( + "json_tuple requires at least 2 arguments (json_string, field1), got {}", + args.arg_fields.len() + ); + } + + let num_fields = args.arg_fields.len() - 1; + let fields: Fields = (0..num_fields) + .map(|i| Field::new(format!("c{i}"), DataType::Utf8, true)) + .collect::<Vec<_>>() + .into(); + + Ok(Arc::new(Field::new( + self.name(), + DataType::Struct(fields), + true, + ))) + } + + fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> { + let ScalarFunctionArgs { + args: arg_values, + return_field, + .. + } = args; + let arrays = ColumnarValue::values_to_arrays(&arg_values)?; + let result = json_tuple_inner(&arrays, return_field.data_type())?; + + Ok(ColumnarValue::Array(result)) + } +} + +fn json_tuple_inner(args: &[ArrayRef], return_type: &DataType) -> Result<ArrayRef> { + let num_rows = args[0].len(); + let num_fields = args.len() - 1; + + let json_array = args[0] + .as_any() + .downcast_ref::<StringArray>() Review Comment: Thanks. Updated to use `as_string_array`. -- 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] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
