DASH app producing error, but python function works outside of the app

Dash Python
1

Hi I’m trying to create a DASH app to pull financial data from yahoo finance.

The code is below. If you take the code in between “ticker = args” (and replace this with either an input function ,or just specify a stock symbol as a string), and is_df = is_df.astype(float), the code works fine and you can create graphs of the data using seaborn or matplotlib. However when I place the code within the callback, it tells me that it’s getting this error: TypeError: can only concatenate str (not “tuple”) to str

import dash
import dash_core_components as dcc
import dash_html_components as html
import plotly.express as px
from dash.dependencies import Input, Output
import pandas as pd  
import numpy as np
from bs4 import BeautifulSoup
import requests
import json

app = dash.Dash(__name__)
app.layout = html.Div([
    # Input the stock ticker
    html.Div([
        dcc.Input(id="input",
                  placeholder='Please insert stock', type="text"),
        dcc.Graph(id = 'revenue')
    ])
])

@app.callback(Output("input", "value"),
              [Input("input", "n_submit")])   
def enter_key(n_sub):
    return n_sub
    
@app.callback(Output('revenue', 'figure'),
             Input('input', 'value'))
def update_figs(*args):
    ticker = args
    url_stem = 'https://finance.yahoo.com/quote/'
    url_full = url_stem + ticker+'/financials'
    response = requests.get(url_full)
    soup = BeautifulSoup(response.content, 'lxml')
    income_statement_data = soup.find_all('div', {'class':'D(tbr)'})
    columns = []
    for x in income_statement_data[0]:
        temp = x.text
        columns.append(temp)
    rows = []
    for x in income_statement_data:
        temp = x.find_all('div', class_= 'D(tbc)')
        rows.append(temp)
    rows = rows[1:] #Get rid of the first row since it's just None
    r = []
    for x in rows:
        s = []
        for i in x:
            temp = i.text
            s.append(temp)
        r.append(s)
    is_df = pd.DataFrame(r)
    is_df.columns = columns
    is_df = is_df.set_index('Breakdown')
    columns = list(is_df.columns)
    for x in columns:
        is_df[x] = is_df[x].str.replace(',','')
        is_df[x] = is_df[x].str.replace('-','')
        is_df[x] = is_df[x].replace(r'^\s*$', np.nan, regex=True)
        is_df[x] = is_df[x].fillna(0)
        is_df[x] = is_df[x].astype(float)
    dash_is_df = is_df.T.reset_index()
    figure = px.bar(dash_is_df, x = 'index', y = 'Total Revenue')`
    return figure

if __name__ == '__main__':
    app.run_server(debug=True, use_reloader=False)
2

Hi @jwang25 and welcome to the Dash community! :grinning:

I’m just guessing here — since I didn’t test this…

but try removing the errant ` from the very end of this statement:

figure = px.bar(dash_is_df, x = 'index', y = 'Total Revenue')`
3

Haha no, that was just a typo when I copy pasted for my post, the script runs, the problem is that it’s not taking inputs correctly

4

Hi @jwang25,

Why you are using a callback to overwrite the Input value?

The problem is solved if you change the def argument directy for ticker:

def update_figs(ticker):

Also include the debounce=True property in the Input to avoid sending incompleate or None Ticker value to the callback.

5

Sorry I’m a bit slow to this. I had tried update_figs(ticker, input, etc) but it said that the value was not found