Difficulties using button with session_state

Using Streamlit
, ,
1

Hi, I am creating a support web app to help the support team at my company, at the moment is running locally.
Is a simple application, will receive a number and execute a ‘select’ on database and show to user. After this, I want a second button be enabled when the query is shown on the screen.
So is a button to consult and other (to delete a line in db). But I can’t make it work, any help is welcome I’m open to advice.

Python 3.12.3
Streamlit, version 1.34.0

2

Hi @bentohiago, welcome to the forum!

Can you give a simplified example showing what you’ve tried, and what has gone wrong?

Here’s a very simple example that might be helpful using st.session_state as a fake database.

import streamlit as st

if "fake_db" not in st.session_state:
    st.session_state["fake_db"] = [
        {"id": 1, "name": "John Doe", "email": "john@doe.com"},
        {"id": 2, "name": "Jane Doe", "email": "jane@doe.com"},
    ]


def get_all_usernames():
    return [user["name"] for user in st.session_state["fake_db"]]


def get_user_by_name(name):
    return next(
        (user for user in st.session_state["fake_db"] if user["name"] == name), None
    )


def delete_user(user_id):
    st.session_state["fake_db"] = [
        user for user in st.session_state["fake_db"] if user["id"] != user_id
    ]


@st.experimental_dialog("Add user")
def add_user():
    name = st.text_input("Name")
    email = st.text_input("Email")
    if st.button("Add"):
        st.session_state["fake_db"].append(
            {"id": len(st.session_state["fake_db"]) + 1, "name": name, "email": email}
        )
        st.rerun()


selected_user = st.selectbox("Select a user", [None] + get_all_usernames())

selected_user_data = get_user_by_name(selected_user)

if selected_user_data:
    st.write(f"Name: {selected_user_data['name']}")
    st.write(f"Email: {selected_user_data['email']}")

    st.button("Delete user", on_click=delete_user, args=(selected_user_data["id"],))
else:
    if st.button("Add user"):
        add_user()
3

Hi, thanks man!

In below a simple example, a part of the full code.

I realize that the delete button ( btns[1] ) only activates when I click Two times on the first button.

[up there is the conection with database]

# start state
if 'botao_ativo' not in st.session_state:
    st.session_state.botao_ativo = False    

# if 'resultados_exibidos' not in st.session_state:
#     st.session_state.resultados_exibidos = False


# Title
st.title('Consulta Imagem GED')

# Caixa de texto para o campo EMPRESA DO CTE
emp = st.text_input('Digite a EMPRESA DO CTE:', placeholder= "Qualquer empresa do Sistema Senior")

# Caixa de texto para o campo NUM
num = st.text_input('Digite o NUMERO DO CTE:', placeholder="EX: '4665656' ou '4665656, 4665657'")


# Botoes para Consultar e deletar
btns = st.columns((3,3,7))

with btns[0]:
    consultar_bt = st.button('Consultar')

with btns[1]:
    deletar_bt = st.button("Deletar", key="del", type="primary", disabled=not st.session_state.botao_ativo)

# Botão para iniciar a consulta
if consultar_bt:
   
    # verifica se o campo empresa está preenchido
    if emp == "" and num != "":

        # Separa itens por vírgula
        lista_num = num.split(",")
        resultados = []

        # Verifica se possui apenas 1 número e executa a consulta se sim
        if len(lista_num) == 1:
            resultado = consult_ged_emp(lista_num[0])
            resultados.extend(resultado)
        else:
            # Se tiver mais de 1 número
            for num_cte in lista_num:
                resultado = consult_ged_emp(num_cte)
                resultados.extend(resultado)

        # Show Results to user
        if resultados:
            st.markdown('<h2>Resultado da consulta:</h2>', unsafe_allow_html=True)
            for resultado in resultados:
                #st.write(resultado)
                st.markdown(f"""
                <div style="background-color: #708090; padding: 10px; margin: 10px 0; border-radius: 5px; color: #000;">
                    <strong>Empresa:</strong> {resultado["empresa"]}<br>
                    <strong>Usuário:</strong> {resultado["usuario"]}<br>
                    <strong>Data e Arquivo:</strong> {resultado["data_arq"]}
                </div>
                """, unsafe_allow_html=True)     
            st.session_state.botao_ativo = True  # Atualiza o estado para indicar que os resultados foram exibidos   
        elif resultado:
            st.markdown('<h2>Resultado da consulta:</h2>', unsafe_allow_html=True)
            st.write(resultado)
            st.session_state.botao_ativo = True  # Atualiza o estado para indicar que os resultados foram exibidos
        else:
            st.error('Nenhum resultado encontrado para os valores fornecidos.')
            st.session_state.botao_ativo = False # atualiza o estado para indicar que os resultados nao foram exibidos
4

That’s because the streamlit script runs from top to bottom on any input, so in this case what happens is, if I’m reading your code correctly:

  1. You push btns[0]
  2. You check to see if butao_ativo is true, it’s not, so btns[1] stays disabled
  3. You check btns[0] and do a bunch of stuff if it’s clicked, including changing butao_ativo.

Note that 3 happens after 2, so it won’t be until the next time the script runs that btns[1] is active.

There are two ways around this:

  1. Move the code that should run if btns[0] is clicked into a function, and do on_click=that_function. on_click functions like that always run as if they were at the top of the script, so if you change butao_ativo inside of that function, it will be changed by the time the script gets to btns[1].
  2. After you change butao_ativo in your current script, call st.rerun() to rerun the script from top to bottom.
5

Ok, I will try.
I hope to do this in the best way.

6

I think its solved.

In addition to create a function to if btns, I turn the list resultados in a st.session_state.resultados = [...] , help me a use better the list.

Now I have problems to use @st.experimental_dialog conditionaly, but I that is problem to annother topic.

Thanks a lot for the help.

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