Trying to store multiple structure from st_ketcher, but keep getting resets

[jeawallace]

I have a very simple streamlit ketcher implementation that draws a molecule, which I then want to have a button to store the content. This is the section of code that’s relevant, I’ve removed references to other elements not in play.

    scaffold_list = []
    scaffold = ""
    col1, col2, col3 = st.columns([50, 30, 20])

    with col1:
        scaffold = st_ketcher(height=650, molecule_format="MOLFILE", key="ketcher")

        if st.button(
            "Store Core",
        ):
            if len(scaffold) > 0 and scaffold not in scaffold_list:
                scaffold_list.append(scaffold)

        st.write("Cores to Run")

        for scaffold in scaffold_list:
            # DO STUFF

So far, so good, but what I’ve found is that, despite scaffold_list being global, every time I update the ‘scaffold’ ketcher object with apply, the list is cleared and I can’t store anything. What am I missing to keep that list of strings alive? I don’t normally have to put non Streamlit elements in session storage, but I’m wondering if that’s what’s needed

[Goyo]

When you press the button, the script reruns and all the variables in the script are lost. scaffold_list seems to be session-scoped, so having it in session state looks like the right thing to do if you want to keep it across reruns.