[Django的] django.db.utils.IntegrityError

Question

my app named mainsite

I have the table class named Weather in models.py

class Weather(models.Model):
    tpr = models.CharField(max_length=5)
    wet = models.CharField(max_length=5)
    ur = models.CharField(max_length=5)
    li = models.CharField(max_length=5)
    observe_time = models.DateTimeField(default=None)

I don't want my observe_time set any deafult value

So I set to None .

I have made migrations.

when I made migrate

Then the traceback happen:

File "manage.py", line 22, in execute_from_command_line(sys.argv)

File "C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\core\\management__init__.py",

line 354, in execute_from_command_line

 utility.execute() File "C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\core\\management\\__init__.py", 

line 346, in execute

 self.fetch_command(subcommand).run_from_argv(self.argv) File "C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\core\\management\\base.py", 

line 394, in run_from_argv

 self.execute(*args, **cmd_options) File "C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\core\\management\\base.py", 

line 445, in execute

 output = self.handle(*args, **options) File "C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\core\\management\\commands\\migrate.py", 

line 222, in handle

 executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial) File 

"C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\db\\migrations\\executor.py",

line 110, in migrate

 self.apply_migration(states[migration], migration, fake=fake, fake_initial=fake_initial) File 

"C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\db\\migrations\\executor.py",

line 148, in apply_migration

 state = migration.apply(state, schema_editor) File "C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\db\\migrations\\migration.py", 

line 115, in apply

 operation.database_forwards(self.app_label, schema_editor, old_state, project_state) File 

"C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\db\\migrations\\operations\\fields.py",

line 62, in database_forwards

 field, File "C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\db\\backends\\sqlite3\\schema.py", 

line 179, in add_field

 self._remake_table(model, create_fields=[field]) File "C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\db\\backends\\sqlite3\\schema.py", 

line 147, in _remake_table

 self.quote_name(model._meta.db_table), File "C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\db\\backends\\base\\schema.py", 

line 111, in execute

 cursor.execute(sql, params) File "C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\db\\backends\\utils.py", 

line 79, in execute

 return super(CursorDebugWrapper, self).execute(sql, params) File "C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\db\\backends\\utils.py", 

line 64, in execute

 return self.cursor.execute(sql, params) File "C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\db\\utils.py", line 

98, in exit

 six.reraise(dj_exc_type, dj_exc_value, traceback) File "C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\utils\\six.py", line 

685, in reraise

 raise value.with_traceback(tb) File "C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\db\\backends\\utils.py", 

line 64, in execute

 return self.cursor.execute(sql, params) File "C:\\Users\\User\\Anaconda3\\lib\\site-packages\\django\\db\\backends\\sqlite3\\base.py", 

line 318, in execute

 return Database.Cursor.execute(self, query, params) django.db.utils.IntegrityError: NOT NULL constraint failed: 

mainsite_weather__new.observe_time

I don't know what caused this error.

thx.

Answer 1

In order for this to work you should also make this field nullable and blankable, like this:

observe_time = models.DateTimeField(default=None, blank=True, null=True)

or omit default=None completely, like this:

observe_time = models.DateTimeField(blank=True, null=True)

Also, after that, don't forget to delete the previous migration file and run makemigrations and migrate again.