ReactPy in the Browser #1096

rmorshea · 2023-07-11T07:10:51Z

rmorshea
Jul 11, 2023
Maintainer

It's not pretty, but the fact that I was able to hack together a prototype of ReactPy running in the browser using PyScript in just a few hours is kind of amazing. https://guileless-monstera-ca2caa.netlify.app/

For posterity, here's the source:

<html>
  <head>
    <!-- HTML Meta Tags -->
    <title>ReactPy + PyScript</title>
    <meta name="description" content="A demo of ReactPy running in the browser with PyScript">

    <!-- Facebook Meta Tags -->
    <meta property="og:url" content="https://guileless-monstera-ca2caa.netlify.app/">
    <meta property="og:type" content="website">
    <meta property="og:title" content="ReactPy + PyScript">
    <meta property="og:description" content="A demo of ReactPy running in the browser with PyScript">
    <meta property="og:image" content="https://raw.githubusercontent.com/reactive-python/reactpy/main/branding/png/reactpy-logo-landscape-padded.png">

    <!-- Twitter Meta Tags -->
    <meta name="twitter:card" content="summary_large_image">
    <meta property="twitter:domain" content="guileless-monstera-ca2caa.netlify.app">
    <meta property="twitter:url" content="https://guileless-monstera-ca2caa.netlify.app/">
    <meta name="twitter:title" content="ReactPy + PyScript">
    <meta name="twitter:description" content="A demo of ReactPy running in the browser with PyScript">
    <meta name="twitter:image" content="https://raw.githubusercontent.com/reactive-python/reactpy/main/branding/png/reactpy-logo-landscape-padded.png">

    <!-- Actual Header -->
    <link rel="stylesheet" href="https://pyscript.net/latest/pyscript.css" />
    <script defer src="https://pyscript.net/latest/pyscript.js"></script>
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@picocss/pico@1/css/pico.min.css">
  </head>
  <body>
    <main class="container">
        <h1>Simple Counter App</h1>
        <div id="root">
            <article aria-busy="true"></article>
        </div>
        <h1>Source Code</h1>
        <a href="https://github.com/reactive-python/reactpy"><img src="https://github-link-card.s3.ap-northeast-1.amazonaws.com/reactive-python/reactpy.png" width="460px"></a>
        <pre id="source-code-view"></pre>
    </main>
    <py-config>
      packages = ["reactpy", "ssl", "jsonpointer"]
      
      [splashscreen]
      enabled = false
    </py-config>
    <py-script id="source-code-content">
        import js
        import asyncio
        from reactpy import html, component, use_state
        from reactpy.core.layout import Layout
        from jsonpointer import set_pointer
        from pyodide.ffi.wrappers import add_event_listener

        # --- Application Code ---------------------------------------------------------

        @component
        def app():
            value, set_value = use_state(0)
            return html.article(
                html.div(
                    {"class": "grid"},
                    html.button({"on_click": lambda event: set_value(value + 1)}, "+"),
                    html.button({"on_click": lambda event: set_value(value - 1)}, "-"),
                ),
                "Current value",
                html.pre({"style": {"font-style": "bold"}}, str(value)),
            )

        # --- Framework Code ---------------------------------------------------------

        model = {}

        def apply_update(update):
            if update["path"]:
                set_pointer(model, update["path"], update["model"])
            else:
                model.update(update["model"])

        def render_model(layout, model):
            root = js.document.getElementById("root")
            root.innerHTML = ""
            _render_model(layout, root, model)

        def _render_model(layout, parent, model):
            if isinstance(model, str):
                parent.appendChild(js.document.createTextNode(model))
            elif isinstance(model, dict):
                if not model["tagName"]:
                    for child in model.get("children", []):
                        _render_model(layout, parent, child)
                    return
                tag = model["tagName"]
                attributes = model.get("attributes", {})
                children = model.get("children", [])
                element = js.document.createElement(tag)
                for key, value in attributes.items():
                    if key == "style":
                        for style_key, style_value in value.items():
                            setattr(element.style, style_key, style_value)
                    else:
                        element.setAttribute(key, value)
                for event_name, event_handler_model in model.get("eventHandlers", {}).items():
                    _create_event_handler(layout, element, event_name, event_handler_model)
                for child in children:
                    _render_model(layout, element, child)
                parent.appendChild(element)
            else:
                raise ValueError(f"Unknown model type: {type(model)}")

        def _create_event_handler(layout, element, event_name, event_handler_model):
            target = event_handler_model["target"]

            def event_handler(*args):
                asyncio.create_task(layout.deliver({
                    "type": "layout-event",
                    "target": target,
                    "data": args,
                }))

            event_name = event_name.lstrip("on_").lower().replace("_", "")
            add_event_listener(element, event_name, event_handler)

        async def main():
            async with Layout(app()) as layout:
                while True:
                    update = await layout.render()
                    apply_update(update)
                    render_model(layout, model)

        asyncio.create_task(main())
    </py-script>
    <script>
        const sourceCodeView = document.getElementById("source-code-view");
        const sourceCodeContent = document.getElementById("source-code-content");
        sourceCodeView.innerText = sourceCodeContent.innerText;
    </script>
  </body>
</html>

yessycedeno84 · 2024-04-23T23:13:30Z

yessycedeno84
Apr 23, 2024

I tested this code running locally in pyscript 2024.4.1 configured with pyodide-0.26.0a4 as the interpreter and everything OK, but I got the following error when I tried to use reactpy_router to create routes RuntimeError: No backend established a connection. Are there plans to fully support pyscript? Or how can I workaorund this to make routing work when using pyscript?

6 replies

bitnom Oct 18, 2024

This would make a lot of sense to put on the roadmap, don't you think? Suggestion though: pyodide is probably much better supported and into the future. Cloudflare are using it for their Workers. I think wasmer are using it for their edge solution as well.

https://wasmer.io/posts/py2wasm-a-python-to-wasm-compiler
https://developers.cloudflare.com/workers/languages/python/

ReactPy Router currently doesn't take pyscript into account. We'd need to make a few compatibility changes to get this working.

If you make a comprehensive explanation of what needs to be done to make it work, geared towards someone who has not yet contributed to reactpy, I wouldn't mind taking a crack at a PR.

Archmonger Oct 18, 2024
Maintainer

I just finished rewriting ReactPy-Router today, which resolves all major issues.

In all likelihood, I will create another minor release to ReactPy-Router in the next two weeks which includes pyscript support and scroll_restoration.

As a reminder, right now the only officially support PyScript environment is contained within ReactPy-Django.

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ReactPy in the Browser #1096

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rmorshea Jul 11, 2023 Maintainer

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yessycedeno84 Apr 23, 2024

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Archmonger Oct 18, 2024 Maintainer

rmorshea
Jul 11, 2023
Maintainer

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yessycedeno84
Apr 23, 2024

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