I want to remove null=True from a TextField:
- footer=models.TextField(null=True, blank=True)
+ footer=models.TextField(blank=True, default="")
I created a schema migration:
manage.py schemamigration fooapp --auto
Since some footer columns contain NULL
I get this error
if I run the migration:
django.db.utils.IntegrityError: column "footer" contains null values
I added this to the schema migration:
for sender in orm["fooapp.EmailSender"].objects.filter(footer=None):
sender.footer=""
sender.save()
Now I get:
django.db.utils.DatabaseError: cannot ALTER TABLE "fooapp_emailsender" because it has pending trigger events
What is wrong?
Django-DB-Migrations: cannot ALTER TABLE because it has pending trigger events __del__: Questions
How can I make a time delay in Python?
5 answers
I would like to know how to put a time delay in a Python script.
Answer #1
import time
time.sleep(5) # Delays for 5 seconds. You can also use a float value.
Here is another example where something is run approximately once a minute:
import time
while True:
print("This prints once a minute.")
time.sleep(60) # Delay for 1 minute (60 seconds).
Answer #2
You can use the sleep()
function in the time
module. It can take a float argument for sub-second resolution.
from time import sleep
sleep(0.1) # Time in seconds
Django-DB-Migrations: cannot ALTER TABLE because it has pending trigger events __del__: Questions
How to delete a file or folder in Python?
5 answers
How do I delete a file or folder in Python?
Answer #1
os.remove()
removes a file.os.rmdir()
removes an empty directory.shutil.rmtree()
deletes a directory and all its contents.
Path
objects from the Python 3.4+ pathlib
module also expose these instance methods:
pathlib.Path.unlink()
removes a file or symbolic link.pathlib.Path.rmdir()
removes an empty directory.