multiapp.py

"""Frameworks for running multiple Streamlit applications as a single app."""

import streamlit as st

# app_state = st.query_params
# app_state = {k: v[0] if isinstance(v, list) else v for k, v in app_state.items()} # fetch the first item in each query string as we don't have multiple values for each query string key in this example


class MultiApp:
    """Framework for combining multiple streamlit applications.
    Usage:
        def foo():
            st.title("Hello Foo")
        def bar():
            st.title("Hello Bar")
        app = MultiApp()
        app.add_app("Foo", foo)
        app.add_app("Bar", bar)
        app.run()
    It is also possible keep each application in a separate file.
        import foo
        import bar
        app = MultiApp()
        app.add_app("Foo", foo.app)
        app.add_app("Bar", bar.app)
        app.run()
    """

    def __init__(self):
        self.apps = []

    def add_app(self, title, func):
        """Adds a new application.
        Parameters
        ----------
        func:
            the python function to render this app.
        title:
            title of the app. Appears in the dropdown in the sidebar.
        """
        self.apps.append({"title": title, "function": func})

    def run(self):
        app_state = st.query_params
        app_state = {
            k: v[0] if isinstance(v, list) else v for k, v in app_state.items()
        }  # fetch the first item in each query string as we don't have multiple values for each query string key in this example

        # st.write('before', app_state)

        titles = [a["title"] for a in self.apps]
        functions = [a["function"] for a in self.apps]
        default_radio = titles.index(app_state["page"]) if "page" in app_state else 0

        st.sidebar.title("Navigation")

        title = st.sidebar.radio("Go To", titles, index=default_radio, key="radio")

        app_state["page"] = st.session_state.radio
        # st.write('after', app_state)

        st.experimental_set_query_params(**app_state)
        # st.experimental_set_query_params(**st.session_state.to_dict())
        functions[titles.index(title)]()

        st.sidebar.title("About")
        st.sidebar.info(
            """
            The web app URL: <https://scholar.gishub.org>. If you have any questions regarding this web app, please contact [Qiusheng Wu](https://wetlands.io) (qwu18@utk.edu).
        """
        )