我尝试在这个 Django 模型上进行迁移/迁移:

from django.db import models 
from myapp.models import Site 
 
class GscElement(models.Model): 
    ctr = models.FloatField('Taux de clic', default=0.0) 
    impressions = models.IntegerField('Nombre d\'impressions', default=0) 
    position = models.FloatField('Position moyenne', default=0.0) 
    clicks = models.IntegerField('Nombre de clics', default=0) 
    site = models.ForeignKey( 
        Site, 
        models.SET_NULL, 
        blank=True, 
        null=True 
    ) 
 
class Page(GscElement): 
    page_field = models.TextField('Url de la page', default='') 
    startdate = models.DateField('Date du debut', null=True) 
    enddate = models.DateField('Date de fin', null=True) 
 
    class Meta: 
        unique_together = (('startdate', 'enddate', 'page_field',)) 
 
class Query(GscElement): 
    query_field = models.TextField('Requête', default='') 
    startdate = models.DateField('Date du debut', null=True) 
    enddate = models.DateField('Date de fin', null=True) 
 
    class Meta: 
        unique_together = (('startdate', 'enddate', 'query_field'),) 

我得到这个错误:

 Applying gsc.0004_auto_20171024_1916...Traceback (most recent call last): 
  File "manage.py", line 22, in <module> 
    execute_from_command_line(sys.argv) 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/core/management/__init__.py", line 364, in execute_from_command_line 
    utility.execute() 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/core/management/__init__.py", line 356, in execute 
    self.fetch_command(subcommand).run_from_argv(self.argv) 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/core/management/base.py", line 283, in run_from_argv 
    self.execute(*args, **cmd_options) 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/core/management/base.py", line 330, in execute 
    output = self.handle(*args, **options) 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/core/management/commands/migrate.py", line 204, in handle 
    fake_initial=fake_initial, 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/db/migrations/executor.py", line 115, in migrate 
    state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial) 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/db/migrations/executor.py", line 145, in _migrate_all_forwards 
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial) 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/db/migrations/executor.py", line 244, in apply_migration 
    state = migration.apply(state, schema_editor) 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/db/migrations/migration.py", line 129, in apply 
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state) 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/db/migrations/operations/fields.py", line 87, in database_forwards 
    field, 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/db/backends/sqlite3/schema.py", line 238, in add_field 
    self._remake_table(model, create_field=field) 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/db/backends/sqlite3/schema.py", line 113, in _remake_table 
    self.effective_default(create_field) 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/db/backends/base/schema.py", line 229, in effective_default 
    default = field.get_db_prep_save(default, self.connection) 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/db/models/fields/__init__.py", line 770, in get_db_prep_save 
    prepared=False) 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/db/models/fields/__init__.py", line 762, in get_db_prep_value 
    value = self.get_prep_value(value) 
  File "/Users/Quentin/git/myapp/myapp_env/lib/python3.6/site-packages/django/db/models/fields/__init__.py", line 1781, in get_prep_value 
    return float(value) 
ValueError: could not convert string to float:  

你知道为什么吗？

仅供引用，我尝试恢复我在模型更改之前拥有的数据库，并尝试压缩迁移，但同样的错误总是发生。

谢谢!

编辑:我粘贴了所有回溯

请您参考如下方法:

如果没有看到迁移文件，我不能肯定地说。发布这些会有所帮助。也就是说，您似乎试图将 ctr 或 position 从字符串字段重命名为浮点字段。

这可能发生在您运行 makemigrations 时，它询问您是否重命名了一个字段。如果您不关心那些字段中的数据，您可以执行以下操作:

1. 删除最新的迁移
2. 再次恢复数据库
3. 再次运行 python manage.py makemigrations
4. 当它询问您是否重命名字段时，请回答“否”。

Django 无法将字符串隐式转换为 float ，因此如果您确实需要保留当前存储在模型中的数据，我建议如下:

1. 创建一个新的 float 字段2
2. 运行管理命令从一个字段中获取数据，将其转换为 float ，并将其保存到另一个字段
3. 删除第一个(字符串)字段
4. 将第二个字段( float 字段)重命名为您需要的任何名称。