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🖌️ Code Formatting

Generated code is automatically formatted using code formatters. By default, black and isort are used to produce consistent, well-formatted output.

🎯 Default Behavior

datamodel-codegen --input schema.yaml --output model.py

This runs the following formatters in order:

  1. isort - Sorts and organizes imports
  2. black - Formats code style

🛠️ Available Formatters

Formatter Description
black Code formatting (PEP 8 style)
isort Import sorting
ruff-check Linting with auto-fix
ruff-format Fast code formatting (black alternative)

⚡ Using ruff instead of black

Ruff is a fast Python linter and formatter. To use it:

# Use ruff for both linting and formatting
datamodel-codegen --formatters ruff-check ruff-format --input schema.yaml --output model.py

# Use ruff-format as a black replacement
datamodel-codegen --formatters isort ruff-format --input schema.yaml --output model.py

🚫 Disable formatting

datamodel-codegen requires at least one formatter when using the CLI --formatters option.

To disable built-in formatting entirely, configure it via pyproject.toml:

pyproject.toml
[tool.datamodel-codegen]
formatters = []

⚙️ Configuration via pyproject.toml

Formatters read their configuration from pyproject.toml. The tool searches for pyproject.toml in:

  1. The output file's directory
  2. Parent directories (up to the git repository root)

📝 Example Configuration

pyproject.toml
[tool.black]
line-length = 100
skip-string-normalization = true

[tool.isort]
profile = "black"
line_length = 100

[tool.ruff]
line-length = 100

[tool.ruff.format]
quote-style = "single"

💬 String Quotes

By default, string quote style is determined by your formatter configuration. To force double quotes regardless of configuration:

datamodel-codegen --use-double-quotes --input schema.yaml --output model.py

This overrides skip_string_normalization in black config.

🎨 Custom Formatters

You can create custom formatters for specialized formatting needs. See Custom Formatters for details.

📖 See Also