better-dash-callback

A library that enables running clientside callback functions in Dash applications using Python syntax, eliminating the need for inline JavaScript.

Problem

When building Dash applications, you often need to write clientside callback functions using inline JavaScript. This can be cumbersome and error-prone, especially for complex logic. Moreover, inline JavaScript code lacks syntax highlighting and debugging capabilities.

Solution

better-dash-callback provides a solution to this problem by allowing you to write clientside callback functions using Python syntax. This makes your code more readable, maintainable, and efficient.

Dependencies

better-dash-callback depends on metapensiero.pj, a Python-to-JavaScript compiler that allows you to write Python code that can be executed in a JavaScript environment.

Supported Python-to-JavaScript Syntax

The supported Python-to-JavaScript syntax is listed in the metapensiero.pj documentation. This includes support for many Python features, such as functions, classes, loops, and conditional statements.

Example

Let's consider a simple example where we want to update the text of a component based on the value of an input component.

Using Dash's clientside_callback

from dash import clientside_callback

clientside_callback(
    """
    function(value) {
        return 'You entered: ' + value;
    }
    """,
    Output("output", "children"),
    Input("input", "value")
)

Using better-dash-callback

from better-dash-callback import callback

@callback(
    Output("output", "children"),
    Input("input", "value"),
    clientside=True
)
def update_output(value):
    return f"You entered: {value}"

As you can see, the better-dash-callback example is more elegant and easier to read. You can write your callback function using Python syntax, without having to worry about inline JavaScript code, and the code you write also includes all the python syntax highlighting rather than being javascript code inside of a python string.

The callback function takes the following additional arguments:

• clientside: A boolean indicating whether the callback should be executed on the client-side (default is False).
• disable_es6: A boolean indicating whether to disable ES6 syntax in the generated JavaScript code and revert back to ES5 support (default is False).
• enable_stage3: A boolean indicating whether to enable Stage 3 syntax in the generated JavaScript code (default is False).
• Any arguments and keyword-arguments supported by dash.callback are also supported by better-dash-callback.callback

Installation

To install better-dash-callback, you can use pip:

pip3 install better-dash-callback

License

better-dash-callback is licensed under the MIT License.