Read values from a TOML file

Goal: Read a single value, or a whole table, out of a TOML file such as Cargo.toml or pyproject.toml.

Prerequisites: The built-in toml module. Read the file with -I raw to get its text as a single string.

Query

The dependencies as a Markdown table:

$ mq -I raw 'import "toml" | toml::toml_parse | get("dependencies") | toml::toml_to_markdown_table' Cargo.toml

Input (Cargo.toml)

[package]
name = "demo"
version = "0.3.1"
edition = "2021"

[dependencies]
serde = "1.0"
clap = { version = "4.5", features = ["derive"] }
miette = "7"

Output

| Key | Value |
| --- | --- |
| clap | {"features": ["derive"], "version": "4.5"} |
| miette | 7 |
| serde | 1.0 |

Notes

• One value: mq -I raw 'import "toml" | toml::toml_parse | get("package") | get("version")' Cargo.toml prints 0.3.1.
• The crate names only, as JSON: mq -I raw -F json 'import "toml" | toml::toml_parse | get("dependencies") | keys' Cargo.toml returns ["clap", "miette", "serde"].
• toml_to_json(data) serializes a parsed file as compact JSON.
• toml_stringify writes TOML back, but it sorts keys and drops comments. To change one value in place and keep the rest of the file as it is, see Bump a version string across a file.