lazyfast

LazyFast is a lightweight Python library for building modern, component-based web interfaces using FastAPI. It handles server-side logic in Python, with interactive elements like inputs and buttons triggering server-side component reloads for dynamic state updates.

Documentation / Examples

Ideal for Python developers who:

• Have basic HTML and CSS knowledge and want to build web interfaces without learning complex frontend frameworks like React, Angular, or Vue.

Suitable for projects that:

• Have low to medium traffic and can benefit from server-side rendering to offload work from the client's machine. (Note: High traffic may increase server costs due to backend load.)
• Require quick prototyping and demos without involving frontend developers. LazyFast offers more flexibility than tools like Streamlit, which can be limiting and produce similar-looking applications.

Key Features

• Component-Based Server Rendering
  • Build interfaces with lazy-loaded components that encapsulate logic, state, and presentation.
• Server-Side Logic
  • Manage interactions and state on the server, reducing client-side complexity.
• FastAPI Integration
  • Components and pages are FastAPI endpoints, supporting dependency injection and other features.
• Lightweight
  • Dependencies: FastAPI for Python and HTMX for JavaScript (included via CDN).
• State Management
  • Use a state manager to trigger component reloads for a reactive user experience.

Installation

To install LazyFast, use pip:

pip install lazyfast

or

poetry add lazyfast

Quick Start

Here's an example application to demonstrate how LazyFast works:

from fastapi import FastAPI, Request
from lazyfast import LazyFastRouter, Component, tags


# LazyFastRouter inherits from FastAPI's APIRouter
router = LazyFastRouter()

# Define a lazy-loaded HTML component powered by HTMX
@router.component()
class MyComponent(Component):
    title: str

    async def view(self, request: Request) -> None:
        tags.h1(self.title, class_="my-class")

        with tags.div(style="border: 1px solid black"):
            tags.span(request.headers)

# Initialize the page dependencies for component rendering
# The page endpoint is also a FastAPI endpoint
@router.page("/{name}")
def root(name: str):
    with tags.div(class_="container mt-6"):
        MyComponent(title=f"Hello, World from {name}")

# Embed the router in a FastAPI app
app = FastAPI()
app.include_router(router)

If you use uvicorn instead as a server and want to reload on changes, use the following command:

uvicorn app:app --reload --timeout-graceful-shutdown 1

License

LazyFast is licensed under the MIT License.

Roadmap

• Cache system for HTML tags
• Component templates with popular CSS frameworks (Bootstrap, Bulma, etc.)
• Advanced state management
• Closer integration with HTMX
• ...