Download dataframe as csv from Flask
Question
I am trying to download the dataframe as csv using button click but unable to figure it out how - Please help me as I am new to flask
here is the code -
df is the pandas dataframe that i want to download as csv
Flask code
@app.route('/submit',methods=['POST'])
def submit():
** So here is some code for manipulation **
df = calc.get_data(prdrop,fr_value,sumprfit,fitids)
return render_template('plot.html',url=plot_url)
Plot.html - it gives some graph and a button to download the datasheet as csv
<body>
<img src="data:image/png;base64,{{url}}" alt="Chart" height="auto" width="80%">
<form action="/download" method="POST">
<input type="Submit" value="Download excel" >
</form>
</body>
Now I understand that I need a new url route to get that df into that and then allow user to download it, could you please help me out regarding how will I access the dataframe in new url and allow user to download it as csv
2 answers
solution1
1 2020-07-09 21:03:12
Flask:
html: <a href="{{url_for('get_csv', filename= 'some_csv')}}" id="download" class="btn btn-outline-info">Download</a>
@app.route('/submit',methods=['POST'])
def submit():
** So here is some code for manipulation **
df = calc.get_data(prdrop,fr_value,sumprfit,fitids)
session["some_csv"] = df.to_csv(index=False)
return render_template('plot.html',url=plot_url)
@app.route("/get_csv/<filename>", methods=['GET', 'POST'])
def get_csv(filename):
df = session["some_csv"]
try:
return send_file(df,
mimetype='"text/csv"',
as_attachment=True,
attachment_filename=filename
)
except FileNotFoundError:
abort(404)
solution2
1
You could use sessions. For example:
Python file
First part:
import io
from flask import Flask, render_template, session, send_file
import pandas as pd
app = Flask(__name__)
# Set the secret key to some random bytes and keep it secret.
# A secret key is needed in order to use sessions.
app.secret_key = b"_j'yXdW7.63}}b7"
Submit function:
@app.route("/submit", methods=["GET", "POST"])
def submit():
# Example dataframe
df = pd.DataFrame(
data={
"city": ["Seville", "London", "Berlin"],
"country": ["Spain", "United Kingdom", "Germany"]
}
)
# Store the CSV data as a string in the session
session["df"] = df.to_csv(index=False, header=True, sep=";")
return render_template("plot.html")
Download function:
@app.route("/download", methods=["POST"])
def download():
# Get the CSV data as a string from the session
csv = session["df"] if "df" in session else ""
# Create a string buffer
buf_str = io.StringIO(csv)
# Create a bytes buffer from the string buffer
buf_byt = io.BytesIO(buf_str.read().encode("utf-8"))
# Return the CSV data as an attachment
return send_file(buf_byt,
mimetype="text/csv",
as_attachment=True,
attachment_filename="data.csv")
Last part:
if __name__ == "__main__":
app.run()
HTML file ( templates/plot.html )
<body>
<form action="/download" method="POST">
<input type="Submit" value="Download CSV" >
</form>
</body>
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