How to create a `add filter` button which creates a new set of fields everytime it is clicked

🎈 Using Streamlit
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1

Hello All,

I am new to streamlit. I want to create a form where user can provide multiple filters on the table columns and download data from table based on these filters. Here the table is static.

I want to create a add_filter button which creates a new set of fields everytime it is clicked.
fields set:
filer: selectbox, options=[‘col1’,‘col2’,‘col3’]
operator: selecbox, options= [‘=’,‘!=’,‘>’,‘>=’,‘<’,‘<=’]
value: textbox
connector: selectbox, options=[‘And’,‘Or’]

I wrote function to create dynamic field set but it is not working. Provided code below.

Code snippet:

## function for dynamic filter
def addFilterSet():
    col1 = st.session_state.col1
    col2 = st.session_state.col2
    col3 = st.session_state.col3
    col4 = st.session_state.col4
    counter = st.session_state.counter

    filter_val = col1.selectbox('Field', ['Select','Col1','Col2','Col3'], index=0, key='filter'+str(counter))
    operator_val = col2.selectbox('Operator', ['Select','>','>=','<','<=','=','!='], index=0, key='operator'+str(counter))
    value_val = col3.text_input('Value',placeholder='Enter', key='value'+str(counter))
    connector_val = col4.selectbox('Connector', ['Select','And','Or'], index=0, key='connector'+str(counter))
    st.session_state.counter += 1

## form creation
with st.container():
    st.header('Filter Section')

    col1, col2, col3, col4 = st.columns([2,1,2,1])
    if 'col1' not in st.session_state:
        st.session_state.col1 = col1
        st.session_state.col2 = col2
        st.session_state.col3 = col3
        st.session_state.col4 = col4
        st.session_state.counter = 0

    st.button(label='Add Filter', key='add_filter', on_click=addFilterSet())

Expected behavior:
Initially, only Add filter button should be present on the form
A new field set to be created everytime the Add filter button is clicked

Actual behavior:

Initially, one field set is appearing along with Add filter button. Once I clicked the button, getting error pop
Screenshot from 2023-05-27 19-05-43

Please let me know how to acheive the desired function.

Thank you,
Sownik Turaga.