How to populate a streamlit selectbox with vlaues from a SQL query-CodePudding

The goal is to have a streamlit selectbox show a list of pairs coming from the symbol column from the database.

cursor.execute("""
SELECT symbol FROM pair LIMIT 3
""")

pairs = cursor.fetchall()

st.write(pairs)

The output is

[
  0:[
   0:"ETHBTC"
  ]
  1:[
   0:"LTCBTC"
  ]
  2:[
   0:"BNBBTC"
  ]
]

I have a nested for loop to retrieve the symbol of each pair

for list in pairs:
    for pair in list:
        st.write(pair)

The output is:

ETHBTC
LTCBTC
BNBBTC

So far so good. But when I load it into the selectbox the behavior gets weird. This is just one example but I have many variants of unwanted result.

st.sidebar.selectbox('Select symbol', pair)

B
N
B
B
T
C

I'm stuck for a few hours now. Would be great if someone could help me out. Thank you.

CodePudding user response：

You have to pass a sequence to a selectbox and each element of that sequence will be shown as a possible element to select. I assume what you are passing is pair = 'BNBBTC'. This means every character becomes one value you could choose. However, what you have to pass to your select box would be choices = ['ETHBTC', 'LTCBTC', 'BNBBTC'].

As fetchall returns a list of tuples, you can get that as options = [row[0] for row in cursor.fetchall()] and finally do st.sidebar.selectbox('Select symbol', options)

CodePudding user response：

Assuming you are adding the selectbox inside of the for loop, what is happening is that Python treats a string as an iterable set of characters. st.sidebar.selectbox expects an iterable (something list-like), and thus takes each character and makes it an option in the selectbox.

I'm not quite sure I'm understanding the data structure you show as JSON (?), but I would use a list-comprehension to just pull the values out you want. Something to the effect of

pairs = [x[0][0] for x in cursor.fetchall()]