pymutantic 0.2.0

No project description provided

User-friendly tool for combining pycrdt and pydantic.

Overview

• pymutantic.MutantModel - A type safe pycrdt.Doc ⟷ pydantic pydantic.BaseModel mapping with granular editing.
• pymutantic.JsonPathMutator - Make edits using json path.

Installation

pip install pymutantic

Usage

MutantModel

Given a pydantic schema...

from pydantic import BaseModel, Field
from typing import List

class Author(BaseModel):
    id: str
    name: str

class Comment(BaseModel):
    id: str
    author: Author
    content: str

class Post(BaseModel):
    id: str
    title: str
    content: str
    author: Author
    comments: List[Comment] = Field(default_factory=list)

class BlogPageConfig(BaseModel):
    collection: str
    posts: List[Post] = Field(default_factory=list)

Create pycrdt documents from instances of that schema using the state constructor parameter:

from pycrdt_utils import MutantModel

# Define the initial state
initial_state = BlogPageConfig(
    collection="tech",
    posts=[
        Post(
            id="post1",
            title="First Post",
            content="This is the first post.",
            author=Author(id="author1", name="Author One"),
            comments=[],
        )
    ]
)

# Create a CRDT document with the initial state
doc = MutantModel[BlogPageConfig](state=initial_state)

Get a binary update blob from the CRDT, for example for sending over the wire to other peers:

uri = "ws://example.com/websocket"
async with websockets.connect(uri) as websocket:
    await websocket.send(doc.update)

Instantiate documents from a binary update blob (or multiple using the updates parameter which accepts a list of update blobs):

uri = "ws://example.com/websocket"
async with websockets.connect(uri) as websocket:
    doc = MutantModel[BlogPageConfig](update=websocket.recv())

Make granular edits with the mutate function (applied within a transaction):

# Mutate the document
with doc.mutate() as state:
    state.posts[0].comments.append(Comment(
        id="comment1",
        author=Author(id="author2", name="Author Two"),
        content="Nice post!",
    ))
    state.posts[0].title = "First Post (Edited)"

There is also a JsonPathMutator class which can be used to make edits to the document using json path:

# Mutate the document
from pycrdt_utils import JsonPathMutator
with doc.mutate() as state:
    mutator = JsonPathMutator(state=state)
    mutator.set("$.posts[0].title", "Updated First Post")