django - UNIQUE CONSTRAINED FAILED Fehler

Question

Dies ist, was mein models.py wie folgt aussieht:

from django.db import models 
    from django.core.validators import RegexValidator 

    # Create your models here. 
    class Customer(models.Model): 
     customer_id = models.AutoField(primary_key=True,unique=True) 
     full_name = models.CharField(max_length=50) 
     user_email = models.EmailField(max_length=50) 
     user_pass = models.CharField(max_length=30) 

     def __str__(self): 
      return "%s" % self.full_name 

    class CustomerDetail(models.Model): 
     phone_regex = RegexValidator(regex = r'^\d{10}$', message = "Invalid format! E.g. 4088385778") 
     date_regex = RegexValidator(regex = r'\d{2}[-/]\d{2}[-/]\d{2}', message = "Invalid format! E.g. 05/16/91") 

     address = models.CharField(max_length=100) 
     date_of_birth = models.CharField(validators = [date_regex], max_length = 10, blank = True) 
     company = models.CharField(max_length=30) 
     home_phone = models.CharField(validators = [phone_regex], max_length = 10, blank = True) 
     work_phone = models.CharField(validators = [phone_regex], max_length = 10, blank = True) 
     customer_id = models.ForeignKey(Customer, on_delete=models.CASCADE) 

I customer_id zu Customer hinzugefügt, nachdem ich das gleiche in CustomerDetail als Fremdschlüssel hinzugefügt. Warum bekomme ich diesen Fehler nach dem Ausführen der Migration noch, auch nachdem ich unique=True zu customer_id hinzugefügt habe?

Error: 
     Rendering model states... DONE 
     Applying newuser.0003_auto_20160823_0128...Traceback (most recent call last): 
      File "/home/krag91/Documents/djangodev/virtualenv /lib/python3.5/site-packages/django/db/backends/utils.py", line 64, in  execute 
    return self.cursor.execute(sql, params) 
      File "/home/krag91/Documents/djangodev/virtualenv /lib/python3.5/site-packages/django/db/backends/sqlite3/base.py", line 337, in execute 
    return Database.Cursor.execute(self, query, params) 
     sqlite3.IntegrityError: UNIQUE constraint failed:  newuser_customer.customer_id 
The above exception was the direct cause of the following exception: 

Traceback (most recent call last): 
    File "manage.py", line 22, in <module> 
    execute_from_command_line(sys.argv) 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/core/management/__init__.py", line 367, in execute_from_command_line utility.execute() 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/core/management/__init__.py", line 359, in execute 
    self.fetch_command(subcommand).run_from_argv(self.argv) 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/core/management/base.py", line 305, in run_from_argv 
    self.execute(*args, **cmd_options) 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/core/management/base.py", line 356, in execute 
    output = self.handle(*args, **options) 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/core/management/commands/migrate.py", line 202, in handle 
    targets, plan, fake=fake, fake_initial=fake_initial 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/migrations/executor.py", line 97, in migrate 
    state = self._migrate_all_forwards(plan, full_plan, fake=fake, fake_initial=fake_initial) 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/migrations/executor.py", line 132, in _migrate_all_forwards 
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial) 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/migrations/executor.py", line 237, in apply_migration 
    state = migration.apply(state, schema_editor) 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/migrations/migration.py", line 129, in apply 
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state) 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/migrations/operations/fields.py", line 84, in database_forwards 
    field, 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/backends/sqlite3/schema.py", line 231, in add_field 
    self._remake_table(model, create_fields=[field]) 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/backends/sqlite3/schema.py", line 199, in _remake_table 
    self.quote_name(model._meta.db_table), 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/backends/base/schema.py", line 112, in execute 
    cursor.execute(sql, params) 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/backends/utils.py", line 79, in execute 
    return super(CursorDebugWrapper, self).execute(sql, params) 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/backends/utils.py", line 64, in execute 
    return self.cursor.execute(sql, params) 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/utils.py", line 94, in __exit__ 
    six.reraise(dj_exc_type, dj_exc_value, traceback) 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/utils/six.py", line 685, in reraise 
    raise value.with_traceback(tb) 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/backends/utils.py", line 64, in execute 
    return self.cursor.execute(sql, params) 
    File "/home/krag91/Documents/djangodev/virtualenv/lib/python3.5/site-packages/django/db/backends/sqlite3/base.py", line 337, in execute 
    return Database.Cursor.execute(self, query, params) 
django.db.utils.IntegrityError: UNIQUE constraint failed: newuser_customer.customer_id 

Answer 1

Es scheint, als ob Sie already having some objects as per old model definitions sind. By default django creates a field named as id to every model in database. Zugriffe können über modelName.id erfolgen.

In Ihrem Fall, was passiert ist, ist, dass Sie einige Objekte in der Datenbank mit customer.id so primary wie Primärschlüssel haben. Wenn Sie also die Modelle und angewandten Migrationen geändert haben, existing objects are checked and another unique field is tried to added as a primary key. Hier besteht die Problemumgehung darin, alle vorhandenen Objekte zu löschen, nachdem das Feld customer_id entfernt wurde. Anschließend versuchen Sie, das Feld neu zu erstellen und Migrationen auszuführen.

HTH