Unable to create database when running flask app
Question:
I’m new to flask and I got stuck into one thing. So I have run.py file inside it
from market import app
from market.models import db
if __name__ == "__main__":
with app.app_context():
db.create_all()
app.run(debug=True)
so when I call python run.py the db.create_all() function works. But when I call flask --app market run or flask --app run.py run the db.create_all() doesn’t get executed.
Please explain why this happens ?
Answers:
flask --app run.py run does not execute the contents of your ifmain block, including the db.create_all().
You can/should move the with app.app_context(): db.create_all() out of the ifmain.
When you run python run.py, then the value of __name__ inside your run.py is __main__. That’s why if __name__ == "__main__" condition satisfies and db.create_all() executed.
When you don’t execute your main script directly but with flask cli, the value of the __name__ in run.py file is equal to your file name. So your if condition is false and db.create_all() is not executed.
In addition, __name__ is a special built-in variable in python that provides the name of the current module. Check this answer to learn more about it What does if __name__ == "__main__": do?
I have figured out the answer. Do export FLASK_APP=run.py , then running flask --app run.py run runs perfectly.
I’m new to flask and I got stuck into one thing. So I have run.py file inside it
from market import app
from market.models import db
if __name__ == "__main__":
with app.app_context():
db.create_all()
app.run(debug=True)
so when I call python run.py the db.create_all() function works. But when I call flask --app market run or flask --app run.py run the db.create_all() doesn’t get executed.
Please explain why this happens ?
flask --app run.py run does not execute the contents of your ifmain block, including the db.create_all().
You can/should move the with app.app_context(): db.create_all() out of the ifmain.
When you run python run.py, then the value of __name__ inside your run.py is __main__. That’s why if __name__ == "__main__" condition satisfies and db.create_all() executed.
When you don’t execute your main script directly but with flask cli, the value of the __name__ in run.py file is equal to your file name. So your if condition is false and db.create_all() is not executed.
In addition, __name__ is a special built-in variable in python that provides the name of the current module. Check this answer to learn more about it What does if __name__ == "__main__": do?
I have figured out the answer. Do export FLASK_APP=run.py , then running flask --app run.py run runs perfectly.