Files
mizan/backends/mizan-django
Ryth Azhur 7fb0c4a400 Mutation→context merge primitive across the stack
The @client(merge=[context, ...]) decorator lets a mutation patch its
return value directly into the cached context bundle by matching the
mutation's Output type against each context-function's Output type
to identify the slot, then splicing server-side. Kernel runs
splice_slot on the response to apply locally — no refetch, no
invalidate-cascade.

Lands H14, H15, H16, M19, M20 from ISSUES.md.

Backends (Django + FastAPI):
  _resolve_merges() in both executors walks @client(merge=...) targets,
  resolves the per-context slot via types_match_for_merge, and emits
  {context, slot, value, params?} entries on the response. Param
  auto-scoping mirrors _resolve_invalidation's tier-1 logic.

Frontend kernel (mizan-base):
  Response handler reads the merge[] array and applies splice_slot
  for each entry — locates the cached context bundle by name+params,
  overwrites the named slot with the new value, notifies subscribers.

Core (mizan-python):
  @client decorator extended with merge= parameter. Schema export
  threads merge metadata onto the OpenAPI x-mizan-functions entries.

Examples / fixtures:
  fastapi-react-site harness exercises merge + Playwright spec covers
  the end-to-end happy path (mutation → instant UI update without
  network refetch). AFI fixture's rename_user function is the
  canonical merge target.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-17 18:29:06 -04:00
..

mizan-django

Django backend adapter for the Mizan protocol. One decorator on a server function. Typed React client generated. Invalidation automatic.

Install

uv add "mizan[channels]"
# or with allauth integration:
uv add "mizan[channels,allauth]"

Setup

# settings.py
INSTALLED_APPS = ["mizan", "myapp", ...]

MIZAN_CACHE_SECRET   = "..."   # 32-byte HMAC signing key
MIZAN_CACHE_REDIS_URL = "redis://localhost:6379/0"
MIZAN_MWT_SECRET     = "..."   # MWT signing key (separate from cache + JWT)
# urls.py
from django.urls import include, path

urlpatterns = [
    path("api/mizan/", include("mizan.urls")),
]
# asgi.py — for WebSocket / Channels support
from django.core.asgi import get_asgi_application
from mizan import wrap_asgi

application = wrap_asgi(get_asgi_application())

Define server functions

# myapp/clients.py
from mizan.client import client
from mizan.setup import register
from pydantic import BaseModel


class EchoOutput(BaseModel):
    message: str


@client
def echo(request, text: str) -> EchoOutput:
    return EchoOutput(message=text)


register(echo, "echo")

Auto-discover clients.py modules from each Django app:

# myapp/apps.py
from django.apps import AppConfig


class MyAppConfig(AppConfig):
    name = "myapp"

    def ready(self) -> None:
        from mizan.setup import mizan_clients
        mizan_clients("myapp")  # imports myapp/clients.py — triggers @client side effects

@client parameters

@client                              # plain RPC function
@client(context="global")            # singleton context — fetched once, SSR-hydrated
@client(context="user")              # named context — fetched per provider mount
@client(affects="user")              # mutation — invalidates the user context
@client(affects=user_profile)        # mutation — invalidates a specific function
@client(websocket=True)              # WebSocket transport (requires channels)
@client(auth=True)                   # requires authentication
@client(auth="staff")                # requires is_staff
@client(auth="superuser")            # requires is_superuser
@client(auth=lambda req: ...)        # custom predicate
@client(route="/profile/<id>/")      # view-path function (returns HttpResponse)
@client(rev=2)                       # cache revision (busts on bump)

Forms

Django Forms become server functions + typed React hooks with Zod validation:

from django import forms
from mizan.forms import mizanFormMixin, mizanFormMeta


class ContactForm(mizanFormMixin, forms.Form):
    mizan = mizanFormMeta(name="contact", title="Contact Us", submit_label="Send")

    name    = forms.CharField()
    email   = forms.EmailField()
    message = forms.CharField(widget=forms.Textarea)

    def on_submit_success(self, request):
        send_email(self.cleaned_data)
        return {"sent": True}

Auto-registers contact.schema, contact.validate, contact.submit. Frontend gets useContactForm().

Channels

WebSocket-native RPC via a flag flip:

from pydantic import BaseModel
from mizan.channels import ReactChannel


class ChatChannel(ReactChannel):
    class Params(BaseModel):
        room: str

    class DjangoMessage(BaseModel):
        text: str
        user: str

    def authorize(self, params):
        return self.user.is_authenticated

    def group(self, params):
        return f"chat_{params.room}"

Frontend gets useChatChannel({ room }).

Generate the frontend

The codegen is mizan-generate (in protocol/mizan-generate/). From your frontend project, point a config at the Django backend and run the CLI:

// frontend/django.config.mjs
import path from "path"
import { fileURLToPath } from "url"

const __dirname = path.dirname(fileURLToPath(import.meta.url))
const root = path.resolve(__dirname, "..")

export default {
    source: {
        django: {
            managePath: path.join(root, "backend/manage.py"),
            command: ["uv", "run", "python"],
            env: {
                PYTHONPATH: path.join(root, "backend"),
                DJANGO_SETTINGS_MODULE: "myproject.settings",
            },
        },
    },
    output: "src/api",
}
npx mizan-generate --config django.config.mjs

The codegen drives Django's management command (export_mizan_schema) under the hood, then emits Stage 1 (typed callXxx/fetchXxx over the runtime kernel) + Stage 2 (<MizanContext> provider, per-context providers, use{Hook}() hooks) into src/api/.

// app.tsx
import { MizanContext } from "./api"

export default function App({ children }) {
    return <MizanContext baseUrl="/api/mizan">{children}</MizanContext>
}
// any component
import { useEcho, useCurrentUser } from "./api"

const echo = useEcho()
echo.mutate({ text: "hi" }).then(r => console.log(r.message))

const user = useCurrentUser()  // global context — auto-fetched, auto-refreshed on mutation

Running tests

uv sync --extra dev --extra channels
uv run pytest

Architecture

mizan-django is one of two reference backend adapters (the other is backends/mizan-fastapi). Both implement the same Mizan protocol on top of the shared cores/mizan-python core (@client, registry, MWT, HMAC cache keys). See docs/AFI_ARCHITECTURE.md.