Issue
To set up a simple HTML frontend and a Python flask back-
Test Background Task
- Create a Python script and save D:\Projects\test_backgroundtask:
Code
Import pandas as pd
from Flask import Flask, render_template, request
app = Flask(__name__)
@app.route('/', methods=['GET'])
Def index():
return render_template('views/index.html')
@app.route('/post', methods=['POST'])
Differential post ():
return "received: {}".format(request.form)
if __name__ == "__main__":
app.run( port = '5004')
To create background tasks, flask has a package called flask_executor.
Updated Python script to create background using Excutor
from Flask import Flask, render_template, request
import pandas as pd
fromflask_executor import executor
global input_val
app = Flask(__name__)
def background_task_func(input_val):
If input_val==1:
data = {'Name': ['Tom', 'Joseph', 'Krish', 'John'], 'Age': [20, 21, 19, 18]}
test_val = pd.DataFrame(data)
Print (test_val)
@app.route('/', methods=['GET'])
Def index():
global input_val
input value=1
executor.submit(background_task_func,input_val)
return render_template('views/index.html')
@app.route('/post', methods=['POST'])
Differential post ():
return "received: {}".format(request.form)
if __name__ == "__main__":
executor = executor (app)
app.run( port = '5004')
desired output:
Once the results are complete, you will see a table containing the test_val.
Note: The html page index.html is currently being viewed by the user, and other tables have already been viewed. The user is also interacting with other buttons on this page.
Additional Information
Note: I am using Django inside in my HTML script.
Example used to toggle between tables or buttons:
Solution
Python script
from flask import Flask, render_template, request
import pandas as pd
from flask_executor import Executor
global input_val
global test_val
app = Flask(__name__)
def background_task_func(input_val):
global test_val
data = {'Name': ['Tom', 'Joseph', 'Krish', 'John'], 'Age': [20, 21, 19, 18]}
test_val= pd.DataFrame(data)
if test_val.shape[0]>1:
print(test_val)
return render_template('views/index.html',tables=[test_val.to_html(classes='data')])
@app.route('/', methods=['GET'])
def index():
executor.submit(background_task_func,input_val)
return render_template('views/index.html',tables=[test_val.to_html(classes='data')])
@app.route('/post', methods=['POST'])
def post():
return "recived: {}".format(request.form)
if __name__ == "__main__":
data ={'Name': [], 'Age': []}
test_val= pd.DataFrame(data)
input_val=1
executor = Executor(app)
app.run( port = '5004')
Html code
<html>
<section>
<div>
<h>Test background task</h>
</div>
<div id="demofeatDIV" class="w3-container">
<table class="w3-table-all w3-tiny">
<tbody>
<tr><th>Results</th></tr>
{% for table in tables %}
{{ table|safe }}
{% endfor %}
</tbody>
</table>
<br>
</div>
</section>
</html>
For a simple test example , this method will be fine. However, if there are other data being displayed, the disadvantage of using this method is that I need to refresh the entire page, this results in reloading the previous tables. The alternative solution is to use sockets. My solution in Flask socketio | Emitting a pandas dataframe from a background task using Flask executor to an Html script resolve this issue.
Answered By – Sade
Answer Checked By – Mildred Charles (Easybugfix Admin)