CODEWITHSUNDEEP
pythonrestflask
user159941
user159941

Reputation: 401

Update webpage with cURL and flask

I have started learning flask for web development and experimenting with it since I have a website in mind I would like to create.

My thought has been to create a homepage showing some data that will be updated using cURL or the requests python library. I have some other python code that generates the data to be displayed and I would like to use the POST request for sending a dictionary with the generated information to the server and update the homepage with that new info.

A rather simplistic but comprehensive version of what I have tried so far: 

from flask import Flask, redirect, url_for, render_template, request

app = Flask(__name__)

@app.route("/", methods=["POST", "GET"])
def home():
    if request.method == "POST":
        data = request.form["data"]
        return render_template("index.html", content=data)
    else:
        return render_template("index.html", content="initial_data")


if __name__ == "__main__":
app.run(debug=True)

The code for index.html 

<!doctype html>
<html>
<head>
    <title>Home Page</title>
    </head>
    <body>
        {{content}}
    </body>
</html>

So I would like to send a POST request with some new data to the server and update the webpage with that new data.

import requests
payload = {'data': 'new_data'}
r = requests.post("http://localhost:5000/", data=payload)

All of the above doesn't succeed in updating the data in the webpage when I send a request, it just stays the same. Am I totally off course? Is this even possible in the way I have thought of?

Any comment is much appreciated, thank you.

Upvotes: 0

Views: 310

Answers (1)

Ken Kinder
Ken Kinder

Reputation: 13170

data is staying the same because it's being reassigned each time as a local variable. When a POST request happens, the variable is created, passed to the template, then destroyed as it goes out of scope.

Try this as an experiment in showing how a variable might persist between page loads, though only until the server restarts:

from flask import Flask, redirect, url_for, render_template, request

app = Flask(__name__)

app_state = {
    'data': 'Initial Data'
}


@app.route("/", methods=["POST", "GET"])
def home():
    if request.method == "POST":
        app_state['data'] = request.form['data']
    return render_template("index.html", content=app_state['data'])


if __name__ == "__main__":
app.run(debug=True)

In that example, you're creating a global dictionary, app_date, and updating a key on it every time the user sends a POST request to / with a form payload of data.

Then, we return the template with the content of the dictionary item.

A Few Notes

  • The implementation I provided would still be vulnerable to race conditions if two people make simultaneous changes.
  • For this kind of thing, you'll usually want a more persistent solution, like a database.

Upvotes: 1

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