harshmotw-db commented on code in PR #7783: URL: https://github.com/apache/arrow-rs/pull/7783#discussion_r2181292589
########## parquet-variant/src/from_json.rs: ########## @@ -0,0 +1,149 @@ +// 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. + +//! Module for parsing JSON strings as Variant + +use crate::{ListBuilder, ObjectBuilder, Variant, VariantBuilder, VariantBuilderExt}; +use arrow_schema::ArrowError; +use serde_json::{Number, Value}; + +/// Converts a JSON string to Variant using [`VariantBuilder`]. The resulting `value` and `metadata` +/// buffers can be extracted using `builder.finish()` +/// +/// # Arguments +/// * `json` - The JSON string to parse as Variant. +/// * `variant_builder` - Object of type `VariantBuilder` used to build the vatiant from the JSON +/// string +/// +/// # Returns +/// +/// * `Ok(())` if successful +/// * `Err` with error details if the conversion fails +/// +/// ```rust +/// # use parquet_variant::{ +/// json_to_variant, variant_to_json, variant_to_json_string, variant_to_json_value, VariantBuilder +/// }; +/// +/// let mut variant_builder = VariantBuilder::new(); +/// let person_string = "{\"name\":\"Alice\", \"age\":30, ".to_string() +/// + "\"email\":\"al...@example.com\", \"is_active\": true, \"score\": 95.7," +/// + "\"additional_info\": null}"; +/// json_to_variant(&person_string, &mut variant_builder)?; +/// +/// let (metadata, value) = variant_builder.finish(); +/// +/// let variant = parquet_variant::Variant::try_new(&metadata, &value)?; +/// +/// let json_result = variant_to_json_string(&variant)?; +/// let json_value = variant_to_json_value(&variant)?; +/// +/// let mut buffer = Vec::new(); +/// variant_to_json(&mut buffer, &variant)?; +/// let buffer_result = String::from_utf8(buffer)?; +/// assert_eq!(json_result, "{\"additional_info\":null,\"age\":30,".to_string() + +/// "\"email\":\"al...@example.com\",\"is_active\":true,\"name\":\"Alice\",\"score\":95.7}"); +/// assert_eq!(json_result, buffer_result); +/// assert_eq!(json_result, serde_json::to_string(&json_value)?); +/// # Ok::<(), Box<dyn std::error::Error>>(()) +/// ``` +pub fn json_to_variant(json: &str, builder: &mut VariantBuilder) -> Result<(), ArrowError> { + let json: Value = serde_json::from_str(json) + .map_err(|e| ArrowError::InvalidArgumentError(format!("JSON format error: {e}")))?; + + build_json(&json, builder)?; + Ok(()) +} + +fn build_json(json: &Value, builder: &mut VariantBuilder) -> Result<(), ArrowError> { + append_json(json, builder)?; + Ok(()) +} + +fn variant_from_number<'a, 'b>(n: &Number) -> Result<Variant<'a, 'b>, ArrowError> { + if let Some(i) = n.as_i64() { + // Find minimum Integer width to fit + if i as i8 as i64 == i { + Ok((i as i8).into()) + } else if i as i16 as i64 == i { + Ok((i as i16).into()) + } else if i as i32 as i64 == i { + Ok((i as i32).into()) + } else { + Ok(i.into()) + } + } else { + // Todo: Try decimal once we implement custom JSON parsing where we have access to strings + // Try double - currently json_to_variant does not produce decimal + match n.as_f64() { + Some(f) => return Ok(f.into()), + None => Err(ArrowError::InvalidArgumentError(format!( + "Failed to parse {} as number", + n.to_string() + ))), + }? + } +} + +fn append_json(json: &Value, builder: &mut impl VariantBuilderExt) -> Result<(), ArrowError> { + match json { + Value::Null => builder.append_value(Variant::Null), + Value::Bool(b) => builder.append_value(*b), + Value::Number(n) => { + builder.append_value(variant_from_number(n)?); + } + Value::String(s) => builder.append_value(s.as_str()), + Value::Array(arr) => { + let mut list_builder = builder.new_list(); + for val in arr { + append_json(val, &mut list_builder)?; + } + list_builder.finish(); + } + Value::Object(obj) => { + let mut obj_builder = builder.new_object(); + for (key, value) in obj.iter() { + let mut field_builder = ObjectFieldBuilder { + key, + builder: &mut obj_builder, + }; + append_json(value, &mut field_builder)?; + } + obj_builder.finish().unwrap(); + } + }; + Ok(()) +} + +struct ObjectFieldBuilder<'a, 'b, 'c> { + key: &'a str, + builder: &'b mut ObjectBuilder<'c, 'a>, Review Comment: I've changed it to 's, 'o and 'v where 's is the lifetime of the 's is the lifetime of the string, 'o is the lifetime of [`ObjectBuilder`] and `v` is the lifetime of the variant buffers. -- This is an automated message from the Apache Git Service. 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