default datetime.now value on entries doesnt change unless flask server restarted

Question

Ive noticed that when I submit an entry in my forms page, the date_input will repeat on consequent submissions unless restarted. Why is this happening? I swear that the duplicate times were minutes apart but it seems that the submitted time is only from the server restart. Im also using flask-sqlalchemy.

models.py

class Entry(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(200), unique=True, nullable=False)
    date_input = db.Column(db.DateTime, nullable=False, default=datetime.now(tz=pytz.timezone('Asia/Manila')))

Entry.date_input timestamp results (copy-pasted from cli)

 1. 2020-05-09 00:59:07.269489
 2. 2020-05-09 01:08:56.676228
 3. 2020-05-09 01:10:44.032547
 4. 2020-05-09 01:10:44.032547
 5. 2020-05-09 01:10:44.032547
 6. 2020-05-09 01:10:44.032547
 7. 2020-05-09 01:23:28.636399
 8. 2020-05-09 01:23:28.636399
 9. 2020-05-09 01:23:28.636399

Actual POST logs (copy-pasted from cli)

 1. 127.0.0.1 - - [09/May/2020 01:00:55]
 2. 127.0.0.1 - - [09/May/2020 01:09:25]
 3. 127.0.0.1 - - [09/May/2020 01:14:49]
 4. 127.0.0.1 - - [09/May/2020 01:18:07]
 5. 127.0.0.1 - - [09/May/2020 01:21:39]
 6. 127.0.0.1 - - [09/May/2020 01:23:46]
 7. 127.0.0.1 - - [09/May/2020 01:25:14]
 8. 127.0.0.1 - - [09/May/2020 01:25:14]
 9. 127.0.0.1 - - [09/May/2020 01:25:56]

Server restarts
-I took the timestamps from the first GET result after running the server. 
 The initial running itself doesnt have time indicated

 1. 127.0.0.1 - - [09/May/2020 00:59:11]
 2. 127.0.0.1 - - [09/May/2020 01:09:25]
 3. 127.0.0.1 - - [09/May/2020 01:10:50]
 4. 127.0.0.1 - - [09/May/2020 01:23:31]

Answer 1

Note the difference between a fixed default value and a default function (which provides a value when needed). The documentation shows an example with datetime.now.

Your current code could be rewritten as:

dt = datetime.now(tz=pytz.timezone('Asia/Manila')) # evaluated once
date_input = db.Column(db.DateTime, nullable=False, default=dt)

To fix the code, replace the expression by a function, e.g. default=lambda: datetime.now(tz=...)