[Python] Python Decorator as Callback in Dash Using Dash Object That is an Instance Variable -...

I'm updating some code to use Dash and plotly. The main code for graphing is defined within a class. I replaced some Bokeh widgets with Dash controls, and ended up with a callback that looks like this:

class MakeStuff:
def __init__(self, ..., **optional):
...
self.app = dash.Dash(...)
...

@self.app.callback(
dash.dependencies.Output('indicator-graphic', 'figure'),
[dash.dependencies.Input('start-time-slider', 'value'),
dash.dependencies.Input('graph-width-slider', 'value')]
)
def update_graphs(self,range_start,graph_width):
print(...)


I am following some examples from the Dash website. I was able to run the examples, including callbacks. In my code, without the decorator, the code runs without error, producing the graphics and controls as I expected it to. (Of course, the code is incomplete, but there is no error.) When I include the decorator, I get this error:

NameError: name 'self' is not defined
​

I tired it this way, first, just mimicking the code examples:

class MakeStuff:
def __init__(self, ..., **optional):
...
app = dash.Dash(...)
...

@app.callback(
dash.dependencies.Output('indicator-graphic', 'figure'),
[dash.dependencies.Input('start-time-slider', 'value'),
dash.dependencies.Input('graph-width-slider', 'value')]
)
def update_graphs(self,range_start,graph_width):
print(...)


Of course, the variable "app" is only know within the scope of the init function, so it's no surprise that that doesn't work, giving the similar error:

NameError: name 'app' is not defined
​

Is there a straightforward way to set up this decorator to work while still keeping my code within a class definition? I am guessing some pre-processing is going on with the decorator, but I don't understand it well enough to come up with a solution.

Continue reading...