DataclassMixin

An extension to Python's dataclasses that provides type validation and common data conversion functions.

from dataclasses import dataclass

from dataclass_mixins import DataclassMixin


@dataclass(frozen=True)
class A(DataclassMixin):
    a_a: int
    b_b: str


a = A.create()
a = A.create_strictly(a=1, b='b')

a.serialize()
# {'a_a': 1, 'b_b': 'b'}

a.to_camel_case_json()
# {'aA': 1, 'bB': 'b'}

Coverage

File	Stmts	Miss	Cover(%)	Missing
dataclass_mixin.py	256	1	99.61	28
rule.py	73	0	100
TOTAL	329	1	99.7

Creation

Default Values

When a field is not assigned a value, the default value will be determined based on the following conditions:

1. Use the default or default_factory defined in the field
2. If the field has multiple types and includes None, the default value will be None
3. If the first type of the field is list, set, or dict, create the corresponding container
4. If the first type of the field is a dataclass, create an empty dataclass
5. If none of the above conditions are met, the default value will be None

Data Validation

• During creation, the type of provided parameters will be checked against the types defined in the dataclass
• DataclassMixin.create_strictly() will check if parameter names match the dataclass fields

Conversion Functions

JSON/object to dataclass

Convert data to dataclass as much as possible

• value to value
• dict or custom class to dataclass
• value to Enum
• int, float, Decimal, or date str to datetime
• str to UUID

Special handling for the following cases:

• Enum to value: Check if the value matches the type
• datetime to int: Convert to int(timestamp())
• datetime to float or Decimal: Convert to timestamp()
• UUID to str: Convert to str(uuid)

DataclassMixin.create()

Standard kwargs format

DataclassMixin.create_strictly()

Works the same as DataclassMixin.create(), but checks if parameter names match dataclass fields

DataclassMixin.create_from_camel_case_json()

Convert camel case JSON to dataclass, for example, converting frontend payload to dataclass

DataclassMixin.create_from_object()

• Convert object to dataclass, for example, converting entity to API response dataclass
• Will raise error if object type is dict, suggesting to use create() or create_from_camel_case_json()
• Will raise error if object type is in str, int, float, bool, datetime, Enum, list, tuple, set

Dataclass to JSON

Use dataclasses.asdict() for conversion, with special handling for:

• Enum: Convert to value
• datetime: Convert to timestamp()
• UUID: Convert to str(uuid)

DataclassMixin.serialize()

Basic conversion

DataclassMixin.to_camel_case_json()

Convert all field names to camel case

DataclassMixin.to_snake_case_json()

Convert all field names to snake case

Development

pip install -r tests/requirements.txt
PYTHONPATH=./ pytest --cov=src/ --cov-report=term-missing tests -vv -s