Share state between parent and embedded apps

[MaWeffm]

Dear developers and contributors, fantastic work!

Edit: I guess what it comes down to is whether it is possible to share state between parent and embedded apps. Looking forward to any feedback on this!

I am in the progress of implementing a tool that enables scientists to analyze tabular data. The parent app serves as an entry into the analysis pipeline where you load a pandas data frame as a master table and configure the data set. I was planning to implement wrappers for some external tools, each into their own app, to set tool-specific parameters.

My question is: is it possible to load a data frame in the parent app and communicate it to the embedded apps while interactivity is still maintained? Am I missing something from the documentation? Is there at all a way to achieve this? I'll add a minimal example below that hopefully illustrates my use case. Obviously this is not working. Thanks for reading and please keep up the brilliant work!

# index.py
# cell 1
import marimo as mo
import pandas as pd

# cell 2
from external.gui import app as external_app

# cell 3
external_app_out = await external_app.embed()

# cell 4
b = mo.ui.button(label="Click", on_click=lambda v: load_df())  # button to control the process of loading a data frame
b

# cell 5
def load_df():  # load data frame and update state of external app
    df = pd.read_csv("some.csv", sep="\t")
    external_app_out.defs["set_master"](df)

# cell 6
external_app_out.output  # does not change at all upon calling load_df(), even after rerunning the cell

# cell 7
external_app_out.defs["get_master"]()  # shows data frame only after rerunning the cell

# external/gui.py
# cell 1
import marimo as mo
import pandas as pd

# cell 2
get_master, set_master = mo.state(None)

# cell 3
df_cols = get_master().columns if isinstance(get_master(), pd.DataFrame) else mo.md("empty")
df_cols

[MaWeffm]

Responding to this thread to reactivate it. Is it actually possible to implement a state that is shared between the parent app and an embedded app, and where the embedded app reacts to a changed state in the parent app? Is there a workaround to achieve this? Keep up the great work, developers :)

[dmadisetti]

Sorry for the long response. We're better on discord and issues, but discussions sometimes fall through the cracks.

So you can directly call and import cell defs if you give them a name. Example

nb 1

@app.cell
def makes_output(a, b, c, mo):
   mo.hstack([a,b,c])
   return
   

nb 2

@app.cell
def uses_output(a, b, c, mo):
    from nb1 import makes_output
    makes_output(1, 2, 3, mo) # must provide all args
    makes_output.run(a=2) # provide some args, will run notebook for other args
    return

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Let me know if this helps?