Python:
Working with TOML

How to:

Before diving in, install the toml package with pip install toml. Let’s parse a TOML file:

import toml

# Example TOML content as a string
toml_string = """
[owner]
name = "Tom Preston-Werner"
dob = 1979-05-27T07:32:00Z # First class dates

[database]
server = "192.168.1.1"
ports = [ 8001, 8001, 8002 ]
"""

# Parse the TOML string
parsed_toml = toml.loads(toml_string)

# Accessing data
print(parsed_toml['owner']['name'])  # Output: Tom Preston-Werner
print(parsed_toml['database']['ports'])  # Output: [8001, 8001, 8002]

Deep Dive

TOML was created by Tom Preston-Werner, one of the founders of GitHub, as a more user-friendly configuration file format. It’s designed to unambiguously map to a hash table and be easily parsable by machines.

Compared to JSON, TOML is more readable for config files and supports comments. YAML, another alternative, can be more compact, but its reliance on indentation and subtle issues, like how tabs aren’t allowed, can trip people up.

As for implementation details, TOML values are typed, which includes strings, integers, floats, booleans, datetimes, arrays, and tables. Everything is case-sensitive. Also, TOML supports multi-line strings and, as of the latest version, even allows for heterogeneously typed arrays.

Python uses the toml library, which mirrors the JSON and YAML libraries in terms of API. You have toml.load and toml.loads for reading TOML from a file or a string, respectively, and toml.dump and toml.dumps for writing it out.

See Also

• The official TOML GitHub repository for specs: github.com/toml-lang/toml
• The toml Python library documentation: pypi.org/project/toml/
• Real-world examples of TOML: Config files for Rust’s package manager cargo or the Python packaging tool poetry.