https://github.com/droserasprout/cattrs-extras
Advanced converters for cattrs
https://github.com/droserasprout/cattrs-extras
Last synced: 17 days ago
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Advanced converters for cattrs
- Host: GitHub
- URL: https://github.com/droserasprout/cattrs-extras
- Owner: droserasprout
- License: mit
- Created: 2020-11-10T08:48:23.000Z (over 4 years ago)
- Default Branch: master
- Last Pushed: 2023-10-09T20:05:43.000Z (over 1 year ago)
- Last Synced: 2025-04-10T09:57:59.343Z (21 days ago)
- Language: Python
- Size: 167 KB
- Stars: 4
- Watchers: 1
- Forks: 0
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG
- License: LICENSE
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README
# cattrs-extras
This package contains advanced converter classes for [cattrs](https://github.com/Tinche/cattrs), a great serialization library built around [attrs](https://github.com/python-attrs/attrs).
## Key features
* Support for additional types: Decimal, bool, datetime, date, timedelta
* Alternative structuring algorithm capable of handling complex Unions without registering additional hooks
* Human-readable exceptions on structuring failure
* Support for Tortoise ORM models serialization (including relations)
* Additional class and Tortoise field for reversed enumerations (serialized to member name instead of value)
## Installation
```text
➜ cattrs-extras git:(master) ✗ make
🚧 cattrs-extras developer tools
DEV=1 Whether to install dev dependencies
TAG=latest Tag for the `image` command
help: Show this help (default)
all: Run a whole CI pipeline: lint, run tests, build docs
install: Install project dependencies
lint: Lint with all tools
test: Run test suite
isort: Format with isort
black: Format with black
flake: Lint with flake8
mypy: Lint with mypy
cover: Print coverage for the current branch
build: Build Python wheel package
release-patch: Release patch version
release-minor: Release minor version
release-major: Release major version
clean: Remove all files from .gitignore except for `.venv`
```
## Usage
```python
from enum import Enum
from decimal import Decimal
from datetime import datetime
from attr import dataclass
from cattrs_extras.converter import Converter
class Color(Enum):
RED = 'RED'
GREEN = 'GREEN'
@dataclass(kw_only=True)
class Apple:
weight: Decimal
color: Color
best_before: datetime
sweet: bool
converter = Converter()
raw_apple = {
'weight': '200.5',
'color': 'RED',
'best_before': '2020-04-02T12:00:00',
'sweet': 'true'
}
apple = converter.structure(raw_apple, Apple)
assert apple == Apple(weight=Decimal('200.5'), color=Color.RED, best_before=datetime(2020, 4, 2, 12, 0), sweet=True)
raw_apple = converter.unstructure(apple)
assert raw_apple == {'weight': '200.5', 'color': 'RED', 'best_before': 1585818000.0, 'sweet': True}
```
## Tortoise ORM
Important note: Tortoise ORM has chosen [Pydantic](https://github.com/samuelcolvin/pydantic) as a serialization library, so better to stick with it. However, Pydantic support is still WIP; you can check the current status [here](https://tortoise-orm.readthedocs.io/en/latest/contrib/pydantic.html).
```python
from cattrs_extras.tortoise.converter import TortoiseConverter
from cattrs_extras.tortoise.model import Model
from tortoise import fields
# TODO: ReversedCharEnumField example
class AppleModel(Model):
id = fields.IntField(pk=True)
weight = fields.DecimalField(20, 10)
color = fields.CharEnumField(Color)
best_before = fields.DateField()
sweet = fields.BooleanField()
# NOTE: Replace with module name of your models
tortoise_converter = TortoiseConverter('cattrs_extras.tortoise.model')
apple_model = tortoise_converter.structure(raw_apple, AppleModel)
assert apple_model == AppleModel(weight=Decimal('200.5'), color=Color.RED, best_before=datetime(2020, 4, 2, 12, 0), sweet=True)
raw_apple = tortoise_converter.unstructure(apple_model)
assert raw_apple == {'id': None, 'weight': '200.5', 'color': 'RED', 'best_before': 1585774800.0, 'sweet': True}
```
## Limitations
* [PEP 563 – Postponed Evaluation of Annotations](https://www.python.org/dev/peps/pep-0563/) is not supported. Attempt to import `__future__.annotations` in module containing models will lead to exception. However, you can still use strings as typehints.
* Backward relations in Tortoise models are ignored during structuring even if fetched. Not sure if we should fix it.