Preview variable in callback function (in Colab / Jupyter Notebook)

Dash Python
1

This is a question regarding developing process rather than the outcome.

I am familiar with the jupyter notebook / google colab environment and develop a habit of fragmenting code execution so I can review the output constantly.
However, I am quite confused on how to do that when developing with dash, especially with callback function. Here’s an example:

Blockquote
@callback(
Output(“a_dcc_download”, “data”),
Input(“a_button”, “n_clicks”),
State(“a_datatable”, ‘data’),
State(“a_datatable”, ‘columns’),
)

When I use callback similar to above code, is it possible for me to know what exactly the variable are storing and their corresponding data type? Since I am new to dash and not so familiar with the component property yet, I would like to preview these variable to know what I am inputting, like is it a dict or list?

I have tried ways below:

I try to assign global variable and store the input, but it is not successful

Blockquote
def function(n_clicks, data, column):
global x
x = data

Outcome in colab / jupyter notebook:
image


Another way I have tried is to print output, but when I execute the code, it only output the local link for my site, without executing the print method

image

Lastly I have tried to create a temporary div and output the variable as string to preview it.

Blockquote
html.Div(id=“temp_div”)

@callback(
Output(“temp_div”, “data”),
Input(“a_button”, “n_clicks”),
State(“a_datatable”, ‘data’),
State(“a_datatable”, ‘columns’),
)
def function(n_clicks, data, column):
x = str(data)
return x

This time I succeed and get a string of the variable printed in my site. But it is slow since I need to copy and paste it back to colab / jupyter notebook, store them in a variable and continue my development, especially when the vairable is a very long dictionary / dataframe

My question:
Is there an easier way to let me assign / preview input or output variable in callback when using Colab / Jupyter Notebook?
In the best scenario, I want to store them as a independent or temporary variable which I can use in another code block in Colab / Jupyter Notebook.
Sorry that the question is a bit long, thanks for reading.
2

hi @munchkit

:wave: welcome to the community.

Unfortunately, with jupyter notebook it’s not possible to review your variables inside the callback function. I would have done it the same way you did with a temporary div.