[Python] Export Plotly Dash datatable output to a CSV by clicking download link

Hi Anyone able to help advise? I have an issue trying to export the data being populated from data table filtered from drop down selection upon clicking on download link to a CSV file.

Error gotten after clicking on the Download Link

csv_string = dff.to_csv(index=False, encoding='utf-8')
AttributeError: 'str' object has no attribute 'to_csv'


And the file that was downloaded is a file containing html code.



Code snippets below

import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output,State
import plotly.graph_objs as go
import dash_table
import dash_table_experiments as dt

from urllib.parse import quote

import flask

import pandas as pd

import numpy as np
import pyodbc

app.layout = html.Div([

html.H3("Sales Summary Report"),
dcc.Graph(
figure={
"data": [
{
"x": df["Sales_RANGE"],
"y": df['count'],
"name":'No of Cust',
"type": "bar",
"marker":{'color':'rgba(26, 118, 255, 0.5)',
#'line':{
# 'color':'rgb(8,48,107)',
# 'width':1.5,
# }
}

}
],
"layout": {
"xaxis": {"automargin": True},
"yaxis": {
"automargin": True,
# "title": {"text": column}
},
"height": 250,
"margin": {"t": 10, "l": 10, "r": 10},
},
},
)
,
html.Label(["Select Sales range to view",
dcc.Dropdown(
id="SalesRange",
style={'height': '30px', 'width': '55%'},
options=[{'label': i,
'value': i
} for i in Sales_Range_Options],
value='All'
)
]),


#TABLE
html.H5("Details"),

html.Div(id='detailsresults') ,
html.A('Download Data',
id='download-link',
download="rawdata.csv",
href="",
target="_blank"
)

])


def generate_table(dataframe):
'''Given dataframe, return template generated using Dash components
'''
return html.Div( [dash_table.DataTable(
#id='match-results',

data=dataframe.to_dict('records'),
columns=[{"name": i, "id": i} for i in dataframe.columns],
editable=False
),
html.Hr()
])


@app.callback(
Output('detailsresults', 'children'),
[
Input('SalesRange', 'value'),
]
)


def load_results(SalesRange):
if SalesRange== 'All':
return generate_table(df)
else:
results = df[df['SALES_RANGE'] == SalesRange]
return generate_table(results)


@app.callback(
dash.dependencies.Output('download-link', 'href'),
[dash.dependencies.Input('SalesRange', 'value')])
def update_download_link(SalesRange):
dff = load_results(SalesRange)
csv_string = dff.to_csv(index=False, encoding='utf-8')
csv_string = "data:text/csv;charset=utf-8,%EF%BB%BF" + quote(csv_string)

return csv_string

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