pip install streamlithelpers

Helper functions like set_state(key, value), get_state(key) and init_state(key, value) avoid repetitive if-statement and None checking patterns.

The SessionObject decorator makes it easier to work with Python identifiers as containers of session state instead of passing around String keys to get_state() or set_state().

E.g. the simplest usage might be:

@SessionObject("result")
def result(val):
    return val

Then:

1. Calling result(2) would put 2 in the session state under the key result.
2. You could get the current value by calling result.get(), or
3. Set it to something else like result(3). Or,
4. Set the state value to None with result.clear().
5. Or result.init(2) which calls result(2) only if there isn't a value in the session state already.

But the SessionObject provides other utilities like cleanup functions and history if configured. And the body of the function can do any processing on the inputs before returning the final session state value.

@SessionObject("result", history_size=10, cleanup_func=cleanup)
def result(val):
    # any amount of processing before final val
    return val

Here the last 10 results of calls to result() are stored, and can be acquired via result.history(). And cleanup(result.get()) is run first when result.clear() is called if result.get() is not None.

Some functions are provided which display one or more streamlit widgets to support common workflows. They all start with st_.

Currently, if you make a download button with Streamlit, the contents must already be in memory, so below are some helpers for dealing with that.

st_dataframe_with_download() : displays a st.dataframe() widget with an accompanying download button which downloads a CSV of the dataframe - the button is primed with the full contents of the CSV for you. The dataframe to string conversion is cached for an hour.

st_download_button_via_file() : displays a button which on click performs a save function you specify to a temporary file, then makes a download button that is primed with the contents of that temp file. Useful for big files you only want to generate when the user asks for it, especially if the save function relies on a library function that writes to file.

st_status(message, type) : displays a status message in a colour appropriate to a specified type (error/warn/info/success) with an appropriate icon.

st_source_code(obj) : the streamlit widget st.code() will display only a String literal representing some code. This function takes any Python object, finds its source code via Python's inspect.getsource() and displays that code.

st_code_editor : display a code editor backed by st_ace library, but doing some annoying defaults, like making sure initial state is empty string not None, and that state is initialised.