Multi-page app with session state

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62

When you use an IDE debugger with this code, it can’t get a Session ID from the IDE itself, so you get this message:
" session_id = get_report_ctx().session_id
AttributeError: ‘NoneType’ object has no attribute ‘session_id’
"

I understand why we get this error, but what is the solution? How do we debug our code using the debugger when our local IDE can’t generate a sesion_id?

63

Hello @euler, if you have some data that must be cleared every run, the best way to do it is to keep them out of the session state I guess. Could you describe more precisely your usecase?

64

Hello @ksxx, unfortunately it’s not possible to change widget values programmatically for now. This session state doesn’t support it, and I don’t know any that does.

65

Hello @an_pas, I don’t know that object.

If you’re still encountering this issue,you could maybe use @thiago’s SessionState which does not use any hashing mechanism. My implementation is mostly useful if you want to bind widget values to session state variables.

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66

Hello @OlliePage, your IDE tries to run your app as a regular python script, but in that case it won’t load a ReportContext object.

In your case, try to use this _get_state() function. When run as a script, using a module like sys to keep your session state should work fine.

import sys

# ...

def _get_state(hash_funcs=None):
    try:
        session = _get_session()
    except (AttributeError, RuntimeError):
        session = sys

    if not hasattr(session, "_custom_session_state"):
        session._custom_session_state = _SessionState(session, hash_funcs)

    return session._custom_session_state
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Session state initialization error
67

That did the trick. Thanks very much. That’s made the world of difference.

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68

I tried to set the page config but an error came out stated that I can only call it once. I suspect it’s probably due to how multiple app structure calling it. Is there any hack around this? @okld

StreamlitAPIException : set_page_config() can only be called once per app, and must be called as the first Streamlit command in your script.

How to set page config default layout to wide without calling set_page_config?
69

HI! I have the same problem, i tried your solution but it gives me this error:

NameError: name ‘_get_session’ is not defined

70

I get the same error as well, did you manage to fix this?

71

Hello @Paco_Luna, @apol96,

I guess the script you tried to use was just a reply to another post. I was just a subset of the whole session state implementation.

Streamlit introduced a new session state API that I suggest you use instead. I’ve already uploaded my script to use this new implementation:

72

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