Flask session didn't save changes - flask

Question

I'm writing a document search website on flask. So I have a page where users form query. When a query is posted I save it into the session and create a session variable to keep liked documents.
#app.route('/', methods=['GET', 'POST']) def main():
search_form = SearchForm()
if search_form.is_submitted():
query = FormMainSearchQuery(search_form)
body = {"query": query}
session["body"] = body <<<<<
session["doc_relevance"] = [1, 2, 3] <<<<
resp = es.search(index="test", body=body, size=24) # 7.x
data = resp['hits']['hits']
return jsonify({'html': render_template('doc_cards.html', data=data)})
else:
return render_template('home.html', form=search_form)
I have document cads on the page that users can like or dislike. On click I send XMLHttpRequest
function LikeDislikeDoc (id,relevance) {
const url = '/relevance';
const xhr = new XMLHttpRequest();
sender = JSON.stringify({"id": id, 'doc_relevance': relevance});
xhr.open('POST', url);
xhr.send(sender);
}
Here /relevance page code. I get data and save it into session.
#app.route('/relevance', methods=['POST'])
def relevance():
if request.method == 'POST':
information = request.data
doc_id = json.loads(information)["id"]
doc_relevance = json.loads(information)["doc_relevance"]
print(session['doc_relevance'])
session['doc_relevance'].append((doc_id, doc_relevance))
print(session['doc_relevance'])
return 'ok'
When I liked one document, it works (data is added to the session), but when I liked the next document, it turns out that the first document wasn't saved.
Here prints
* Running on http://127.0.0.1:5000 (Press CTRL+C to quit)
127.0.0.1 - - [12/Aug/2022 20:00:28] "GET / HTTP/1.1" 200 -
127.0.0.1 - - [12/Aug/2022 20:00:28] "GET /static/CSS/main.css HTTP/1.1" 304 -
127.0.0.1 - - [12/Aug/2022 20:00:30] "POST / HTTP/1.1" 200 -
[1, 2, 3]
[1, 2, 3, (86743520, 1)]
127.0.0.1 - - [12/Aug/2022 20:00:31] "POST /relevance HTTP/1.1" 200 -
127.0.0.1 - - [12/Aug/2022 20:00:32] "POST /relevance HTTP/1.1" 200 -
[1, 2, 3]
[1, 2, 3, (86740324, 1)]
What happened?

Answer 1

I found out the problem. You need to explicitly equate the value as here
if request.method == 'POST':
doc_id = request.form["id"]
doc_relevance = request.form["relevance"]
data = session['doc_relevance']
data[str(doc_id)] = doc_relevance
session['doc_relevance'] = data
print(session['doc_relevance'])
return 'ok'
I changed the code a little, but the idea should be understood.