# pytypehintstore

Rows of one validated dataclass, in memory, shadowed by a JSON file you can open and edit. The class is the database.

The file is named for the class and the fingerprint of its compiled schema, so if the file opens, every row in it is valid against this exact schema. Change the contract and it is a new database; the old file stays beside it, whole and readable.

from dataclasses import dataclass
from typing import Annotated
from pytypehint import Max, Min
from pytypehintstore import store_of

@dataclass
class Task:
    title: Annotated[str, Min(1), Max(80)]
    done: bool = False

tasks = store_of(Task, "data")              # data/Task.<fingerprint>.json
row_id = tasks.add(Task(title="Buy milk"))  # 1
tasks.get(row_id)                           # Task(title='Buy milk', done=False)
tasks.close()

The rows live in a dict and every read answers from there; a writer thread carries them to a file named for the class and the fingerprint of its compiled schema, such as Task.ef8e8a47.json. Change one character of the contract, a type, a limit, a default, a Label, and it is a different database: a new file, with the old one left beside it, whole and readable. See The identity.

That is the whole of it, and it is what buys the guarantee: if the file opens, every row in it is valid against this exact schema.

# Quick start

from dataclasses import dataclass
from enum import Enum
from typing import Annotated

from pytypehint import Max, Min
from pytypehintstore import store_of


class Priority(Enum):
    LOW = "low"
    HIGH = "high"


@dataclass
class Task:
    title: Annotated[str, Min(1), Max(80)]
    priority: Priority = Priority.LOW
    done: bool = False


tasks = store_of(Task, "data")
tasks.path.name                        # 'Task.ef8e8a47.json'

first = tasks.add(Task(title="Buy milk", priority=Priority.HIGH))   # 1
second = tasks.add(Task(title="Write the store"))                   # 2

tasks.get(first)                       # Task(title='Buy milk', priority=<Priority.HIGH: 'high'>, done=False)
tasks.put(second, Task(title="Write the store", done=True))
tasks.remove(first)

len(tasks)                             # 1
second in tasks                        # True
tasks.all()                            # [(2, Task(title='Write the store', ...))]

tasks.close()

Reopen it and the rows are there with the same ids; the next add gives 3. The same walk-through, runnable and printing each step, is example.py.

# Alongside

The store defers every validation to pytypehint and fingerprints its compiled schema. The file carries the transport form, the shape pytypehintweb forms speak, which makes a store the small persistence a func-to-web app usually wants, without adding a database to it.