Slightly better example using a dataclass and not passing kwargs:
import streamlit as st
from session_state import get_state
@dataclass
class MyState:
a: int
b: str
def setup() -> MyState:
print('Running setup')
return MyState(a=3, b='bbb')
state = get_state(setup)
st.title('Test state')
if st.button('Increment'):
state.a = state.a + 1
print(f'Incremented to {state.a}')
st.text(state.a)
Iāve been using this setup for the past few days with great success. It really makes buttons more useful when state can be stored.
Is it possible to do an additional simplification of the api?
I imagine you could actual āhideā the setup function in you session_state.py file and change the public api from state = get_state(setup) to state=get_state(a=3, b='bbb').
Hi @Marc, thanks for the feedback. What youāre proposing is basically what was implemented in the original gist if I understood correctly. Let me try to explain why I think my way is an improvement over that for two reasons:
Arguments get evaluated every time thereās a re-run, so if you want to open a database connection and you do state=get_state(db=psycopg2.connect("dbname=test user=postgres password=secret")) youāll be opening it lots of times.
The reason I added a setup function is that this way we can guarantee that the code inside it runs exactly once, which is what a setup should do.
Ideally weād have that in a closure/multi-line lambda but python doesnāt allow those (and regular lambdas are untyped) so I had to make it a function.
You lose typing information. The original get_state is an object that gets added instance variables dynamically, whereas in mine I created a class/dataclass. Since that class/dataclass is the return of my setup function, get_state can infer that itās returning that class/dataclass and then type checking/code complete works in the editor.
AttributeError: āReportSessionā object has no attribute ā_main_dgā
Traceback:
File "e:\anaconda3\envs\myenv\lib\site-packages\streamlit\ScriptRunner.py", line 314, in _run_script
exec(code, module.__dict__)
File "CompareModels_img.py", line 139, in <module>
session_state = SessionState.get(question=1)
File "streamlit_utils.py", line 61, in get
if session_info.session._main_dg == ctx.main_dg:
Hey there! There is a gist for the session state. From streamlit changelog:
If youāre using the SessionState hack Gist, you should re-download it! Depending on which hack youāre using, here are some links to save you some time:
I am having difficulty with a text_area and I am not sure if it is a bug or I just am not putting it together correctly.
I put in a bug report, but maybe I should have started here.
I want to be able to update a text area and maintain the state, but when the text area only seems to update every other change.
import streamlit as st
import SessionState
session_state = SessionState.get(template_string="None")
st.write(session_state.template_string)
template_string = st.text_area("Test", session_state.template_string, height=200)
session_state.template_string = template_string
Can someone use the above example and update the text area a few times and tell me if that is the expected behavior? It seems to only update every other text_area change and revert back to the old state when it doesnāt update.
I solved the issue by doing a rerun each time a value is set in the session state. Feel free to use it as is, or adapt OPās version. Mine doesnāt feature python typing.
Thanks @okld, I am going to try this first thing in the morning! Your demo looks awesome, it makes me more excited to use Streamlit now that I see the possibilities.
@okld I couldnāt wait and fired up my app again and just dropped in your implementation and it seems like everything just worked. I havenāt done any extensive testing, but this looks like it did the trick. THanks again.
Have been jiggling around the session for the past few days now.
a button selection will change the state and idea here is to get multiple inputs from UI and session should be retained until all fields are entered
import streamlit as st
import SessionState
session_state = SessionState.SessionState(id='abc', country='xyz', currency= 'Rupees')
def main () :
rerun = st.button('Rerun')
if rerun :
st.write('Select from the following to add/edit :')
name_dict = {'id': '' , 'country': '', 'currency' : ''}
state = SessionState.get(id='abc', country='xyz', currency= 'Rupees')
for k, v in name_dict.items():
name_dict[k] = st.text_input(k, v)
state.k = name_dict[k]
st.write(name_dict[k])
main()
This does not seem to work.
After 1st input, app gets refreshed and data is lost
Each time you interact with a widget, the whole script reruns. In your example:
I click on Rerun --> the script reruns and the button returns True. I enter the conditional block.
st.text_inputs are created. I input some text in one of them --> As I validate my first input, the whole script reruns, but the Rerun button returns False this time as it doesnāt maintain any state. Widgets disappear and values are lost.
The solution would be to preserve the buttonās state to enter the conditional block as long as inputs are not all filled.
If youāre open to other suggestions, Iād say you should display text_inputs from the beginning, and when you press the button, it does the processing. This way, you donāt need session states anymore, and even for the end-user, it may be better to present things this way.
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