format-json

format-json is a JSON formatter that ships both a standalone CLI and a pre-commit hook. It is adapted from the pretty-format-json pre-commit hook, with only one difference, as seen below.

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Table of Contents

• 1. format-json vs pretty-format-json
• 2. Usage
  • 2.1. As a command-line tool
  • 2.2. As a pre-commit hook
  • 2.3. Configuration options
• 3. Instructions for Maintainers

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1. format-json vs pretty-format-json

Feature	format-json	pretty-format-json
Config option for trailing newline	✅	❌ (Won't implement ever)
Preserves all digits of floats	✅	❌ (Unresolved since 2022)

2. Usage

2.1. As a command-line tool

First, install it:

pip install format-json

Then, in the terminal, you can do something like:

format-json --autofix --no-eof-newline path/to/file.json

All command-line options from pretty-format-json are preserved, with the new --no-eof-newline flag layered on top. See Section 2.3 for the complete set of config options.

2.2. As a pre-commit hook

Add the hook to your .pre-commit-config.yaml:

- repo: https://github.com/jsh9/format-json
  rev: <LATEST_VERSION>
  hooks:
    - id: format-json
      args: [--autofix, --no-eof-newline]

(You can choose your own args.)

2.3. Configuration options

format-json accepts the same options whether invoked via the CLI or pre-commit. Combine them as needed for your workflow:

• --autofix - automatically format json files
• --indent ... - Control the indentation (either a number for a number of spaces or a string of whitespace). Defaults to 2 spaces.
• --no-ensure-ascii preserve unicode characters instead of converting to escape sequences
• --no-sort-keys - when autofixing, retain the original key ordering (instead of sorting the keys)
• --top-keys comma,separated,keys - Keys to keep at the top of mappings.
• --no-eof-newline: omit the trailing newline (format-json only).

3. Instructions for Maintainers

• Run pip install -e . to install this project in the "editable" mode.
• Run pip install -r requirements.dev to install developer dependencies.
• Run pytest to execute the automated tests replicated from the upstream project.
• Use tox to exercise the full test matrix, linting, and formatting targets.