Kivy/Flask data streaming example

README.md

Kivy/Flask data streaming example

The idea here is to send push notifications from server at anytime, by keeping a connection open.

client.py

import os
import socket
import queue
import threading

from kivy.app import App
from kivy.clock import Clock
from kivy.lang import Builder
import requests


KV = r'''
ScrollView:
    Label:
        id: label
        text: 'You are example_name\n'
        size_hint_y: None
        height: self.texture_size[1]
'''


class Stream(App):
    def build(self):
        self.queue = queue.Queue()
        Clock.schedule_interval(self.update_stream, 0)
        threading.Thread(
            target=self.stream_worker,
            daemon=True,
        ).start()

        root = Builder.load_string(KV)
        self.label = root.ids.label

        return root

    def update_stream(self, *args):
        try:
            data = self.queue.get(block=False)
        except queue.Empty:
            return

        self.label.text += f'You won {data} points!\n'

    def stream_worker(self):
        self.response = requests.get(
            'http://localhost:5000/example_name',
            stream=True
        )

        while True:
            for data in self.response.iter_lines(
                chunk_size=1,
                decode_unicode=True
            ):
                self.queue.put(data)


Stream().run()

server.py

import time
import queue

from flask import Flask, Response, request

app = Flask(__name__)

queues = {}


def stream(name):
    queues[name] = stream_queue = queue.Queue()

    while True:
        try:
            yield f'{stream_queue.get()}\n'
        except GeneratorExit:
            break

    del queues[name]


@app.route('/<name>')
def index(name):
    return Response(stream(name), mimetype='text/event-stream')


@app.route('/give', methods=('GET', 'POST'))
def give():
    if request.method == 'POST' and request.form['name'] in queues:
        queues[request.form['name']].put(request.form['points'])

    return (
        '<form method="post">'
        '   Name to give to: <input name="name"><br>'
        '   Points to give: <input name="points"><br>'
        '   <input type="submit">'
        '</form>'
    )

Hello Cheaterman, thanks for your code. It looks exactly what i need for my project but i don't know why this example not works in my case.
I started kivy part with python client.py and flask part with export FLASK_APP=server.py & flask run.
When i open in broswer url http://127.0.0.1:5000/give i see your form, but when i fill fields and submit it, nothing happend. Kivy client is still in state "You are example_name" (in attachment).
Problem is probably on my side, but i don't know what i am doing wrong :/
Please, can you help me how to start your gist?
Thank you.