pitbull

pitbull lets ordinary, JavaScript-free HTML talk to Python while rendered in PyQt5 WebEngine (Chromium). It maps normal relative links and GET form submissions to Python functions in-process: no localhost server, browser automation driver, JavaScript, or custom URL syntax in your HTML.

Install

pip install pitbull

PyQt5 WebEngine is installed automatically as a package dependency.

Example

from pathlib import Path
from pitbull import App

app = App(Path("web"), title="Hello")

@app.event("greet")
def greet(request):
    name = request.form.get("name", "friend")
    return app.render("index.html", message=f"Hello, {name}!")

app.run()

JavaScript toggle

JavaScript is disabled by default. Opt in at startup with App(Path("web"), javascript_enabled=True), or change it at runtime:

app.set_javascript_enabled(True)  # Reloads the current page by default.

To preserve the JavaScript-free model, only enable it for pages you trust.

web/index.html needs no JavaScript:

<!doctype html>
<title>Hello</title>
<form action="/greet" method="get">
  <label>Name <input name="name" required></label>
  <button>Greet</button>
</form>
<p>{{ message }}</p>

Security model

Pitbull has no listening socket. It creates an internal renderer-only URL scheme and restricts static files to web_root. Templates escape values supplied to app.render; do not put untrusted input directly into raw HTML strings returned from a handler.

Plain HTML constraint

Use ordinary relative links and GET forms. For example, action="/greet" calls @app.event("greet"), and href="/settings.html" opens a file in web_root. PyQt5 does not reliably expose POST form bodies through its navigation callback, so use method="get" for Python events. No pitbull:// URL needs to appear in authored HTML.

Scope

JavaScript is disabled through Chromium's managed content setting. This does not produce a custom Chromium binary with V8 physically removed. Building and maintaining such a browser is a separate Chromium-fork project, not something a normal PyPI wheel can safely distribute.