StarModel

Entity-Centric Reactive Development for FastHTML

StarModel enables you to define your application's data structure and behavior in one place, minimizing configuration overhead and maximizing development speed. Build reactive web applications entirely in Python by encapsulating both backend logic and frontend interactivity around your entities.

Core Philosophy

Stop separating your data from your behavior. StarModel brings entity-driven development to web applications:

• State Models - Define your data structure and business logic in unified Python classes
• Event Decorators - Turn methods into interactive SSE endpoints in a same way you use route @rt decorators
• Datastar Integration - Automatic frontend reactivity without writing JavaScript

Technology Stack

• FastHTML - Server-side HTML generation and routing
• Datastar - Lightweight (~15KB) frontend reactivity via SSE
• Pydantic - Type-safe data models with validation

Quick Start

git clone https://github.com/ndendic/StarModel.git
cd StarModel
uv sync
python app/main.py  # Visit http://localhost:5001

or install package like

pip install git+https://github.com/ndendic/StarModel.git

Entity-Centric Development

Below is full example you can run (uses MonsterUI for styling)

from fasthtml.common import *
from monsterui.all import *
from starmodel import *

app, rt = fast_app(
    htmx=False,
    hdrs=(
        Theme.zinc.headers(),
        datastar_script, # <-- Load datastar cdn script
    ),
)

class Counter(State):
    count: int = 0
    update_count: int = 0
    
    @event
    def increment(self, amount: int = 1):
        self.count += amount
        self.update_count += 1

    @event
    def decrement(self, amount: int = 1):
        self.count -= amount
        self.update_count += 1

    @event
    def reset(self):
        self.count = 0
        self.update_count += 1

@rt
def index(req: Request):
    counter = Counter.get(req) # <-- Get your model/state from request or overide `get` for custom logic
    return Main(
        counter, # <-- auto add signals, sync and persistance
        H1("🔢 Counter Demo"),
        # Counter display
        Card(
            Div(
                Span(data_text=Counter.count_signal, cls=TextT.primary + "text-7xl font-bold"),
                cls="text-center mb-2"
            ),
            Div("Total updates: ", Span(data_text=Counter.update_count_signal), cls=TextT.primary),
            cls=CardT.default + "text-center my-6",
        ),            
        # Counter controls
        Div(
            Div(
                Button("-10", data_on_click=Counter.decrement(10), cls=ButtonT.secondary),
                Button("-1", data_on_click=Counter.decrement(1), cls=ButtonT.secondary),
                Button("Reset", data_on_click=Counter.reset(), cls=ButtonT.secondary),
                Button("+1", data_on_click=Counter.increment(1), cls=ButtonT.secondary),
                Button("+10", data_on_click=Counter.increment(10), cls=ButtonT.secondary),
                cls="text-center mb-6 flex gap-2 justify-center"
            ),
            cls="mb-6"
        ),
        # Custom increment
        Div(
            Form(
                Input(name="amount", type="number", value="1", data_bind="$amount",cls="w-24"),
                Button("+", type="submit", cls=ButtonT.secondary),
                data_on_submit=Counter.increment(),
                cls="mb-6"
            ),
            cls="text-center mb-6"
        ),
        cls="container mx-auto p-8 max-w-3xl"
    )

states_rt.to_app(app) # <-- Import and add state routes

if __name__ == "__main__":
    serve(reload=True, port=8080)

Why This Matters

🎯 Entity-Driven Architecture

Your User, Product, Order entities contain both data schema and business logic. No more scattering behavior across controllers, services, and frontend code.

⚡ Zero Configuration Reactivity

The @event decorator automatically creates HTTP endpoints and generates Datastar-compatible URLs. Your methods csn become interactive without routing setup. You can still add all parameters you tipically add to your @route decorators and expect extraction of standard Starlette request, session, and other entities + new datastar object that can be extracted from the request automatically with other signlas sent.

Here is one example - note that it's smaller bit taken examples and cannot be used "as-is"

class Sale(BaseModel):
    name: str
    email: str
    amount: int

class DashboardState(State):
    
    sales: int = 0
    subscriptions: int = 0
    active_now: int = 0
    total_revenue: int = 0
    recent_sales: List[Sale] = []
    
    @event
    async def add_sales(self, amount: int = 0, name: str = "Unknown", email: str = "Unknown"):
        self.sales += 1
        self.total_revenue += amount
        sale = Sale(name=name, email=email, amount=amount)
        self.recent_sales.append(sale)
        yield self.recent_sales_card()
        yield self.sales_chart()

    def recent_sales_card(self):
        return Card(cls="col-span-3", id="recent-sales-card")(
            Div(cls="space-y-8 px-4")(
                *[
                    AvatarItem(n, e, d)
                    for (n, e, d) in (
                        *[(sale.name, sale.email, f"+${sale.amount}") for sale in self.recent_sales],
                    )
                ]
            ),
            header=Div(
                H3("Recent Sales"), P("You made 265 sales this month.", cls=TextPresets.muted_sm)
            ),
        )
    
    def sales_chart(self):
        return Div(id="sales-chart")(
                Apex_Chart(
                    chart_type=ChartT.area,
                    series=[
                        {"name": "2024", "data": [sale.amount for sale in self.recent_sales]},
                    ],
                    categories=[sale.name for sale in self.recent_sales],
                    fill={"type": "gradient", "gradient": {"shadeIntensity": 1, "opacityFrom": 0.4, "opacityTo": 0.1}},
                    cls='max-w-md max-h-md',
                )
            ),

@rt("/dashboard")
def dashboard(request):
    state = DashboardState.get(request)
    return Div(cls="space-y-4")(
        ...
        Form(
            Input(type="text", name="name", data_bind="$name", placeholder="Name"),
            Input(type="email", name="email", data_bind="$email", placeholder="Email"),
            Input(type="number", name="amount", data_bind="$amount", placeholder="Amount"),
            Button("Add Sales", type="submit"),
            data_on_submit=DashboardState.add_sales(),
            
        )
        ...
    )

🔄 Seamless State Synchronization

Changes to your Python objects instantly update the frontend via Server-Sent Events. Two-way data binding works automatically. State class comes with some automatic Datastar helpers that can be used in the front-end:

• MyModel.myArg_signal class atribute will return $myArg or $MyModel.myArg Datastar formated string based on the configured usage of namaspace
• MyModel.myEvent(maybe, some, args) will be converted to @get('/path/to/MyModel/endpoint') also @post, @put and other will be used if specified in @event methods args.
• myModelInstance has opinionated __ft__ function that deturns an empty Div with all the Model signals, persistance options, and sync calls. Overide this method to set how your instance is shown in your FT elements.
• There is much more, so please feel free to explore source code to get max out of it.

📦 Minimal Peripheral Setup

No Redux stores, no API layer design, no frontend state management. Just define your entities and interact with them.

Storage Options

StarModel comes with 3 model storage options, 2 enabled by Datastar persistance in client session and cliend local storage, and one for backend server memory, but it's built to allow user to hook up any custom persistence options like Redis or Database. Just overide standard methods for get, save, delete or extend with your custom logic.

from starmodel import StateStore

class UserProfile(State):
    name: str = ""
    preferences: dict = {}
    
    # Choose your persistence layer
    model_config = {
        "store": StateStore.SERVER_MEMORY,    # Server memory (default)  
        # "store": StateStore.CLIENT_SESSION, # Browser sessionStorage
        # "store": StateStore.CLIENT_LOCAL,   # Browser localStorage
        # "store": StateStore.CUSTOM,         # Custom logic
        "persistence_backend": memory_persistence, # <-- Instance of your persistance manager class
    }

Other Helpful Resources

You can try to combine this library with other FastHTML/Datastar/Pydantic helper libraries for even better dev experience. Here are some of them:

• ft-datastar
• datastar_py attribute helpers
• fh-pydantic-form
• FastSQLModel

Demo Application

Run python app/main.py to see examples of:

• Session-based counters
• Real-time chat
• Form handling with client storage
• Multi-user collaboration

Contributing

This project focuses on eliminating the complexity of modern web development by returning to entity-centric design patterns. Contributions welcome!

License

MIT License