validobj 0.1

A simple validation library.

Validobj

Validobj is library that takes semistructured data (for example JSON and YAML configuration files) and converts it to more structured Python objects. It places the emphasis on good error messages and simplicity of implementation and usage rather than full generality, extensibility or runtime performance. This makes it particularly suitable for processing configuration files and giving good user feedback. It is best viewed as a tool to deal with the heavy lifting of validation, to be complemented by purpose specific checks.

Validobj has no schema and instead relies on newer Python functionality (such as dataclasses) and enums of the data as well as a small subset of the typing module to specify the expected shape.

It requires Python 3.7 and has no other dependencies.

Example

import dataclasses
import enum
from typing import Mapping, Set, Tuple, List

from validobj import parse_input

inp = {
    'global_environment': {'CI_ACTIVE': '1'},
    'stages': [
        {
            'name': 'compile',
            'os': ['linux', 'mac'],
            'script_path': 'build.sh',
            'disk_permissions': ['READ', 'WRITE', 'EXECUTE'],
        },
        {
            'name': 'test',
            'os': ['linux', 'mac'],
            'script_path': 'test.sh',
            'framework_version': [4, 0],
        },
    ],
}


class DiskPermissions(enum.Flag):
    READ = enum.auto()
    WRITE = enum.auto()
    EXECUTE = enum.auto()


class OS(enum.Enum):
    mac = enum.auto()
    windows = enum.auto()
    linux = enum.auto()


@dataclasses.dataclass
class Job:
    name: str
    os: Set[OS]
    script_path: str
    framework_version: Tuple[int, int] = (1, 0)
    disk_permissions: DiskPermissions = DiskPermissions.READ


@dataclasses.dataclass
class CIConf:
    stages: List[Job]
    global_environment: Mapping[str, str] = dataclasses.field(default_factory=dict)



print(parse_input(inp, CIConf))
# This results in a dataclass instance with the correct types:
#
#CIConf(
#    stages=[
#        Job(
#            name='compile',
#            os={<OS.linux: 3>, <OS.mac:1>},
#            script_path='build.sh',
#            framework_version=(1, 0),
#            disk_permissions=<DiskPermissions.EXECUTE|WRITE|READ: 7>,
#        ),
#        Job(
#            name='test',
#            os={<OS.linux: 3>, <OS.mac: 1>},
#            script_path='test.sh',
#            framework_version=(4, 0),
#            disk_permissions='<DiskPermissions.READ: 1>',
#        ),
#    ],
#    global_environment={'CI_ACTIVE': '1'},
#)
#