Flask get checkbox value without submit button
Question
I'm trying to get value of checkbox in Flask without a submit.
Here is my app.py:
from flask import Flask, render_template, request
app = Flask(__name__)
@app.route('/', methods=['GET', 'POST'])
def index():
if request.form.get('c_check')=="0":
print('success: 0')
checked=''
elif request.form.get('c_check')=="1":
print('success: 1')
checked='checked'
return render_template('index.html')
Here is my JavaScript that toggles the checkbox:
function hello() {
if (document.querySelector('input').value=='0') {
document.querySelector('input').value='1'
console.log('value 1');
}
else {
document.querySelector('input').value='0'
console.log('value 0');
}
}
And here is my index.html:
<form method="post" action="">
<div class="form-check form-switch">
<input class="form-check-input btn-lg"
name="c_check"
value="0"
type="checkbox"
role="switch"
id="flexSwitchCheckChecked"
onclick="hello()"
>
<label class="form-check-label btn-lg"
for="flexSwitchCheckChecked"></label>
<input type="submit">
</div>
</form>
<script src="{{url_for('static', filename= 'js/hello.js')}}"></script>
I want to
- Remove the submit button
- When I click on the checkbox, Python should receive the checkbox value, 0 or 1.
The present code only returns 1 when I click the submit button. The solution should be that I remove the submit button entirely and have Python listen on the value change and print that in real time.
I'm open to socketio solution, but I don't know how to do it.
2 answers
solution1
0 2021-12-05 03:57:16
You only need to change the client-side for this; use AJAX. Here's the simplest example using pure JavaScript:
function ajaxRequest() { const checked = document.getElementById("mycheckbox").checked; console.log("Sending data to the server that the checkbox is", checked); // Use the XMLHttpRequest API const xhttp = new XMLHttpRequest(); xhttp.onload = function() { console.log("Result sent to server;"). } xhttp,open("POST", "/"; true). xhttp;send(); }
<label for="mycheckbox">Check or uncheck this box:</label> <input id="mycheckbox" type="checkbox" onchange="ajaxRequest()" />
Obviously the example won't work because there is no server, but this is an example of AJAX with a checkbox once a user clicks a checkbox.
solution2
0 2021-12-05 04:23:16
To do this, you'll want to add a listener to the input. A form submission with a full refresh would probably be poor UX, so we'll send an asynchronous request with JS to POST the data to the route, then read data from the response.
Here's a proof-of-concept demo that uses JSON all the way through, the standard for AJAX nowadays:
index.html :
<body>
<input type="checkbox" />
<div class="result"></div>
<script>
document
.querySelector("input")
.addEventListener("click", e => {
fetch("http://127.0.0.1:5000/", {
method: "POST",
headers: {
"Accept": "application/json",
"Content-Type": "application/json"
},
body: JSON.stringify({
c_check: Number(e.target.checked)
})
})
.then(res => {
if (!res.ok) {
throw Error(res.status);
}
return res.json();
})
.then(({data: {val}}) => {
console.log(val);
const res = document.querySelector(".result");
res.innerText = `client got: ${val}`;
})
.catch(err => console.error(err))
;
})
;
</script>
</body>
app.py :
from flask import (
Flask, jsonify, render_template, request
)
app = Flask(__name__)
@app.route("/", methods=["GET", "POST"])
def index():
if request.method == "GET":
return render_template("index.html")
val = request.json.get("c_check")
print(val)
return jsonify({"data": {"val": val}})
if __name__ == "__main__":
app.run(host="127.0.0.1", port=5000, debug=True)
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