Caching and state
Optimize performance and add statefulness to your app!
Caching
Streamlit provides powerful cache primitives for data and global resources. They allow your app to stay performant even when loading data from the web, manipulating large datasets, or performing expensive computations.
Cache data
Function decorator to cache functions that return data (e.g. dataframe transforms, database queries, ML inference).
@st.cache_data
def long_function(param1, param2):
# Perform expensive computation here or
# fetch data from the web here
return data
Cache resource
Function decorator to cache functions that return global resources (e.g. database connections, ML models).
@st.cache_resource
def init_model():
# Return a global resource here
return pipeline(
"sentiment-analysis",
model="distilbert-base-uncased-finetuned-sst-2-english"
)
Browser and server state
Streamlit re-executes your script with each user interaction. Widgets have built-in statefulness between reruns, but Session State lets you do more!
Context
st.context provides a read-only interface to access cookies and headers.
st.context.cookies
st.context.headers
Session State
Save data between reruns and across pages.
st.session_state["foo"] = "bar"
Query parameters
Get, set, or clear the query parameters that are shown in the browser's URL bar.
st.query_params[key] = value
st.query_params.clear()
Deprecated commands
Get query parameters
Get query parameters that are shown in the browser's URL bar.
param_dict = st.experimental_get_query_params()
Set query parameters
Set query parameters that are shown in the browser's URL bar.
st.experimental_set_query_params(
{"show_all"=True, "selected"=["asia", "america"]}
)
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