json2xml-rs 0.4.2

Fast native JSON to XML conversion - Rust extension for json2xml

json2xml_rs - Rust Extension for json2xml

A high-performance Rust implementation of the dicttoxml module using PyO3.

Building

Prerequisites

• Rust (1.96+)
• Python (3.9+)
• maturin (pip install maturin)

Development Build

cd rust
maturin develop --release

This builds the extension and installs it in your current Python environment.

Production Build

cd rust
maturin build --release

The wheel will be in target/wheels/.

Usage

# Direct usage
from json2xml_rs import dicttoxml

data = {"name": "John", "age": 30, "active": True}
xml_bytes = dicttoxml(data)
print(xml_bytes.decode())

# Or use the hybrid module that auto-selects the fastest backend
from json2xml import dicttoxml_fast
xml_bytes = dicttoxml_fast.dicttoxml(data)

API

dicttoxml(obj, root=True, custom_root="root", attr_type=True, item_wrap=True, cdata=False, list_headers=False) -> bytes

Convert a Python dict or list to XML.

Parameters:

• obj: The Python object to convert (dict or list)
• root: Include XML declaration and root element (default: True)
• custom_root: Name of the root element (default: "root")
• attr_type: Include type attributes on elements (default: True)
• item_wrap: Wrap list items in <item> tags (default: True)
• cdata: Wrap string values in CDATA sections (default: False)
• list_headers: Repeat parent tag for each list item (default: False)

Returns: UTF-8 encoded XML as bytes

escape_xml_py(s: str) -> str

Escape special XML characters (&, ", ', <, >) in a string.

wrap_cdata_py(s: str) -> str

Wrap a string in a CDATA section.

Performance

The Rust implementation is expected to be 5-15x faster than pure Python for:

• String escaping (single-pass vs. multiple .replace() calls)
• Type dispatch (compiled match statements vs. isinstance() chains)
• String building (pre-allocated buffers vs. f-string concatenation)

Version 0.4.2 uses word/SIMD-optimized searches for XML escape bytes while retaining the direct Python bytes writer and its bounded 16 KiB buffer. On the 5,000-record release workload, this reduced median conversion time from 6.007 ms to 5.632 ms (6.23%) with byte-for-byte identical output. The previous 0.4.1 release introduced the bounded writer, building on the roughly 49% lower serializer RSS delta delivered in 0.3.0.

Limitations

The Rust implementation currently does not support:

• ids parameter (unique IDs for elements)
• item_func parameter (custom item naming function)
• xml_namespaces parameter
• xpath_format parameter
• @attrs, @val, @flat special dict keys

For these features, fall back to the pure Python implementation.

Development

Running Tests

cd rust
maturin develop
python -m pytest ../tests/

Benchmarking

cd ..
python benchmark_rust.py