pydbantic 0.0.5

'db' within pydantic - A single model for shaping, creating, accessing, storing data within a Database

'db' within pydantic - A single model for shaping, creating, accessing, storing data within a Database

Key Features

• Integrated Redis Caching Support
• Automatic Migration on Schema Changes
• Flexible Data Types
• One Model to Manage

Setup

$ pip install pydbantic
$ pip install pydbantic[sqlite]
$ pip install pydbantic[mysql]
$ pip install pydbantic[postgres]

Basic Usage - Model

from typing import List, Optional
from pydantic import BaseModel, Field
from pydbantic import DataBaseModel

class Department(DataBaseModel):
    id: str 
    name: str
    company: str
    is_sensitive: bool = False

class Positions(DataBaseModel):
    id: str
    name: str
    department: Department

class EmployeeInfo(DataBaseModel):
    ssn: str
    first_name: str
    last_name: str
    address: str
    address2: Optional[str]
    city: Optional[str]
    zip: Optional[int]

class Employee(DataBaseModel):
    id: str
    employee_info: EmployeeInfo
    position: Positions
    salary: float
    is_employed: bool
    date_employed: Optional[str]

Basic Usage - Connecting a Database to Models

import asyncio
from pydbantic import Database
from models import Employee

async def main():
    db = await Database.create(
        'sqlite:///test.db',
        tables=[Employee]
    )

if __name__ == '__main__':
    asyncio.run(main())

Model Usage

from models import (
    Employee, 
    EmployeeInfo, 
    Position, 
    Department
)

async def main():
    # db creation is above

    # create department 
    hr_department = Department(
        id='d1234',
        name='hr'
        company='abc-company',
        is_sensitive=True,
    )

    # create a Position in Hr Department
    hr_manager = Position(
        id='p1234',
        name='manager',
        department=hr_department
    )

    # create information on an hr employee
    hr_emp_info = EmployeeInfo(
        ssn='123-456-789',
        first_name='john',
        last_name='doe',
        address='123 lane',
        city='snake city',
        zip=12345
    )

    # create an hr employee 
    hr_employee = Employee(
        id='e1234',
        employee_info=hr_emp_info,
        position=hr_manager,
        is_employed=True,
        date_employed='1970-01-01'
    )

Note: At this point only the models have been created, but nothing is saved in the database yet.

    # save to database
    await hr_employee.save()

Filtering

    # get all hr managers currently employed
    managers = await Employee.filter(
        position=hr_manager,
        is_employed=True
    )

Deleting

    # remove all managers not employed anymore
    for manager in await Employee.filter(
        position=hr_manager,
        is_employed=False
    ):
        await manager.delete()

Updating

    # raise salary of all managers
    for manager in await Employee.filter(
        position=hr_manager,
        is_employed=False
    ):
        manager.salary = manager.salary + 1000.0
        await manager.update() # or manager.save()

Save results in a new row created in Employee table as well as the related EmployeeInfo, Position, Department tables if non-existing.

What is pydbantic

pydbantic was built to solve some of the most common pain developers may face working with databases.

• migrations
• model creation / managment
• caching

pydbantic believes that related data should be stored together, in the shape the developer plans to use

pydbantic knows data is rarely flat or follows a set schema

pydbantic understand migrations are not fun, and does them for you

pydbantic speaks many types

Pillars

• pydantic - Models, Type validation
• databases - Database Connection Abstractions
• sqlalchemy - Core Database Query and Database Model

Models

pydbantic most basic object is a DataBaseModel. This object may be comprised of almost any pickle-able python object, though you are encouraged to stay within the type-validation land by using pydantic's BaseModels and validators.

Primary Keys

DataBaseModel 's also have a priamry key, which is the first item defined in a model.

class NotesBm(DataBaseModel):
    id: str              # required - primary key
    text: Optional[str]  # optional
    data: DataModel      # required 
    coridinates: tuple   # required
    items: list          # required
    nested: dict = {'nested': True} # Optional - w/ Default

Model Types & Typing

DataBaseModel items are capable of being multiple layers deep following pydantic model validation

• Primary Key - First Item, must be unique
• Required - items without default values are assumed required
• Optional - marked explicitly with typing.Optional or with a default value
• Union - Accepts Either specified input type Union[str|int]
• List[item] - Lists of specified items

Input datatypes without a natural / built in serialization path are serialized using pickle and stored as bytes. More on this later.

Migrations

pydbantic handles migrations automatically in response to detected model changes: New Field, Removed Field, Modified Field, Renamed Field

Renaming an exiting column

Speical consideration is needed when renaming a field in a DataBaseModel, extra metadata __renamed__ is needed to ensure existing data is migrated:

# field `first_name` is renamed to `first_names`

class EmployeeInfo(DataBaseModel):
    __renamed__= [{'old_name': 'first_name', 'new_name': 'first_names'}]
    ssn: str
    first_names: str
    last_name: str
    address: str
    address2: Optional[str]
    city: Optional[str]
    zip: Optional[int]

Cache

Adding cache with Redis is easy with pydbantic, and is complete with built in cache invalidation.

    db = await Database.create(
        'sqlite:///test.db',
        tables=[Employee],
        cache_enabled=True,
        redis_url="redis://localhost"
    )