django - 類型錯誤：預期的字符串或緩沖區

Question

您好，我向模型添加了一個字段，當我嘗試在終端中進行migrate ，它給了我這個錯誤，有人知道這可能是什么嗎？

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  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/core/management/__init__.py", line 385, in execute_from_command_line
    utility.execute()
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/core/management/__init__.py", line 377, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/core/management/base.py", line 338, in execute
    output = self.handle(*args, **options)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/core/management/commands/migrate.py", line 161, in handle
    executor.migrate(targets, plan, fake=options.get("fake", False))
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/db/migrations/executor.py", line 68, in migrate
    self.apply_migration(migration, fake=fake)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/db/migrations/executor.py", line 102, in apply_migration
    migration.apply(project_state, schema_editor)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/db/migrations/migration.py", line 108, in apply
    operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/db/migrations/operations/fields.py", line 139, in database_forwards
    schema_editor.alter_field(from_model, from_field, to_field)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/db/backends/schema.py", line 454, in alter_field
    self._alter_field(model, old_field, new_field, old_type, new_type, old_db_params, new_db_params, strict)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/db/backends/sqlite3/schema.py", line 199, in _alter_field
    self._remake_table(model, alter_fields=[(old_field, new_field)])
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/db/backends/sqlite3/schema.py", line 137, in _remake_table
    self.create_model(temp_model)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/db/backends/schema.py", line 212, in create_model
    definition, extra_params = self.column_sql(model, field)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/db/backends/schema.py", line 124, in column_sql
    default_value = self.effective_default(field)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/db/backends/schema.py", line 187, in effective_default
    default = field.get_db_prep_save(default, self.connection)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 627, in get_db_prep_save
    prepared=False)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 1290, in get_db_prep_value
    value = self.get_prep_value(value)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 1269, in get_prep_value
    value = super(DateTimeField, self).get_prep_value(value)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 1171, in get_prep_value
    return self.to_python(value)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 1228, in to_python
    parsed = parse_datetime(value)
  File "/Users/Derek/.virtualenvs/tasks/lib/python2.7/site-packages/django/utils/dateparse.py", line 70, in parse_datetime
    match = datetime_re.match(value)
TypeError: expected string or buffer

模型.py

class Lead(models.Model):
    title = models.CharField(choices=TITLE_CHOICES, max_length=20, blank=True, default='')
    first_name = models.CharField(max_length=80, blank=True, default='')
    last_name = models.CharField(max_length=80, blank=True)
    company = models.CharField(max_length=80, blank=True)
    position = models.CharField(max_length=50, blank=True, default='')
    location = models.CharField(max_length=100, blank=True)
    currently_using_sms = models.CharField(choices=CURRENTLY_USING_SMS, default='',  max_length=30)
    services_interested_in = models.ManyToManyField(Services)
    phone_number = models.CharField(blank=True, max_length=20, default='')
    mobile_number = models.CharField(blank=True, max_length=11, default='')
    email = models.EmailField(blank='True', default='')
    best_day_to_contact = models.DateTimeField(blank=False, null=True)
    notes = models.TextField(blank=True)
    assign_to = models.ForeignKey(User, db_index=True, blank=True, null=True, default=None)
    lead_source = models.ForeignKey(LeadSource, db_index=True, blank=True, null=True)
    status = models.CharField(choices=LEAD_STATUS, max_length=100, default='1')

Answer 1

Django 的DateTimeField通常適用於 Python datetime和date對象，但有一個未公開的特性，即能夠自動將字符串解析為datetime對象。 在您的DateTimeField聲明中，您有

default=False

這既不是datetime也不是date 。 因此，Django 會嘗試自動為您解析它。 如果不這樣做，它會發出神秘的消息。

根據您的特定需要，您應該替換或刪除default=False參數。

Answer 2

我相信您在以下行的default=False中有錯誤：

    completion_date = models.DateTimeField(blank=False, null=True, default=False)

False不是default預期的有效日期。 請改用default=datetime.now 。

Answer 3

我以前也有同樣的問題。 我試過 default=False 但它沒有做任何改變。 然后我添加 default=timezone.now，它工作正常。 唯一的問題是日期字段未顯示在管理部分。

更改此字段：

best_day_to_contact = models.DateTimeField(blank=False, null=True)

到這個領域：

from django.utils import timezone
best_day_to_contact = models.DateTimeField(default=timezone.now)

我想也許你的問題會用這個解決方案解決。

Answer 4

/* Example Model */     

class user(models.Model):
    created = models.DateField(auto_now_add=True)
    def __str__(self):
        return str(self.id)

/*When you generate migrations file then it will add (default=1)
*Remove default=1
*field=models.DateField(default=1, auto_now_add=True),
*To 
*field=models.DateField(auto_now_add=True)

*Then do sqlmigrate or migrate.  
*/

Answer 5

只是想權衡一下，因為這個問題讓我很頭疼。 在我添加了一個 models.DateField 之后，Django 陷入了一個糟糕的遷移。 直到我刪除所有遷移並重新運行 makemigrations 后，它才自行修復。

希望這可以幫助！

Answer 6

要解決此問題，您可能需要返回文本編輯器並刪除所有遷移。 它通常發生在 django 進行不良遷移時。 之后重新進行新的遷移。 希望這能解決你的問題