district42 1.5.0

Data description language for defining data models

district42

Data description language for defining data models

(!) Work in progress, breaking changes are possible until v2.0 is released

Installation

pip3 install district42

Usage

from district42 import schema

UserSchema = schema.dict({
    "id": schema.int.min(1),
    "name": schema.str | schema.none,
    "is_deleted": schema.bool,
})

print(UserSchema)

More powerful with:

• blahblah — Fake data generator
• valera — Validator
• revolt — Value substitutor

And more

Documentation

• Documentation
  • None
    • schema.none
  • Bool
    • schema.bool
    • schema.bool(value)
  • Int
    • schema.int
    • schema.int(value)
    • schema.int.min(value)
    • schema.int.max(value)
  • Float
    • schema.float
    • schema.float(value)
    • schema.float.min(value)
    • schema.float.max(value)
  • Str
    • schema.str
    • schema.str.len(length)
    • schema.str.len(min_length, max_length)
    • schema.str.alphabet(letters)
    • schema.str.contains(substr)
    • schema.str.regex(pattern)
  • List
    • schema.list
    • schema.list(elements)
    • schema.list(type)
    • schema.list(type).len(length)
    • schema.list(type).len(min_length, max_length)
  • Dict
    • schema.dict
    • schema.dict(keys)
  • Any
    • schema.any
    • schema.any(*types)
  • Custom Types
    • 1. Declare Schema
    • 2. Register Representor
    • 3. Use

None

schema.none

sch = schema.none

Bool

schema.bool

sch = schema.bool

schema.bool(value)

sch = schema.bool(True)

Int

schema.int

sch = schema.int

schema.int(value)

sch = schema.int(42)

schema.int.min(value)

sch = schema.int.min(0)

schema.int.max(value)

sch = schema.int.max(0)

Float

schema.float

sch = schema.float

schema.float(value)

sch = schema.float(3.14)

schema.float.min(value)

sch = schema.float.min(0.0)

schema.float.max(value)

sch = schema.float.max(0.0)

Str

schema.str

sch = schema.str

schema.str.len(length)

sch = schema.str.len(10)

schema.str.len(min_length, max_length)

sch = schema.str.len(1, ...)

sch = schema.str.len(..., 32)

sch = schema.str.len(1, 32)

schema.str.alphabet(letters)

digits = "01234567890"
sch = schema.str.alphabet(digits)

schema.str.contains(substr)

sch = schema.str.contains("@")

schema.str.regex(pattern)

import re
sch = schema.str.regex(r"[a-z]+")

List

schema.list

sch = schema.list

schema.list(elements)

sch = schema.list([schema.int(1), schema.int(2)])

schema.list(type)

sch = schema.list(schema.int)

schema.list(type).len(length)

sch = schema.list(schema.int).len(3)

schema.list(type).len(min_length, max_length)

sch = schema.list(schema.int).len(1, ...)

sch = schema.list(schema.int).len(..., 10)

sch = schema.list(schema.int).len(1, 10)

Dict

schema.dict

sch = schema.dict

schema.dict(keys)

sch = schema.dict({
    "id": schema.int,
    "name": schema.str | schema.none,
    optional("platform"): schema.str,
})

Any

schema.any

sch = schema.any

schema.any(*types)

sch = schema.any(schema.str, schema.int)

Custom Types

1. Declare Schema

from typing import Any
from uuid import UUID
from district42 import Props, SchemaVisitor, SchemaVisitorReturnType as ReturnType
from district42.types import Schema
from niltype import Nilable


class UUIDProps(Props):
    @property
    def value(self) -> Nilable[UUID]:
        return self.get("value")


class UUIDSchema(Schema[UUIDProps]):
    def __accept__(self, visitor: SchemaVisitor[ReturnType], **kwargs: Any) -> ReturnType:
        return visitor.visit_uuid(self, **kwargs)

    def __call__(self, /, value: UUID) -> "UUIDSchema":
        return self.__class__(self.props.update(value=value))

2. Register Representor

from typing import Any
from district42.representor import Representor
from niltype import Nil


class UUIDRepresentor(Representor, extend=True):
    def visit_uuid(self, schema: UUIDSchema, *, indent: int = 0, **kwargs: Any) -> str:
        r = f"{self._name}.uuid"

        if schema.props.value is not Nil:
            r += f"({schema.props.value!r})"

        return r

3. Use

from uuid import uuid4
from district42 import register_type, schema

register_type("uuid", UUIDSchema)

print(schema.uuid(uuid4()))
# schema.uuid(UUID('ce80d2b7-cdce-4e24-ab26-00c75471ce78'))

Full code available here: district42_exp_types/uuid