Question

这是我的第一个问题，所以我会感激耐心。

我从CharField将一些属性更改为IntegerField。下面列出的是代码：

rating_choices = (
    (1,"1"),
    (2,"2"),
    (3,"3"),
    (4,"4"),
    (5,"5"),
)

class Rating(models.Model):
    article = models.ForeignKey(Article,null=True)
    organization = models.IntegerField(choices=rating_choices, default=1)
    support = models.IntegerField(choices=rating_choices, default=1)
    readability = models.IntegerField(choices=rating_choices, default=1)
    tags = models.IntegerField(choices=rating_choices, default=1)
    comments = models.TextField()
    def get_overall_rating(self):
        return fsum(self.organization + self.support + self.support + self.readability + self.tags)/5.0
    overall_rating = property(get_overall_rating)
admin.site.register(Rating)

我在Postgres上进行了南迁移迁移，这是我得到的错误：

Error in migration: collect_data:0010_auto__chg_field_rating_tags__chg_field_rating_support__chg_field_ratin
Traceback (most recent call last):
  File "manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/django/core/management/__init__.py", line 443, in execute_from_command_line
    utility.execute()
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/django/core/management/__init__.py", line 382, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/django/core/management/base.py", line 196, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/django/core/management/base.py", line 232, in execute
    output = self.handle(*args, **options)
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/south/management/commands/migrate.py", line 108, in handle
    ignore_ghosts = ignore_ghosts,
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/south/migration/__init__.py", line 213, in migrate_app
    success = migrator.migrate_many(target, workplan, database)
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/south/migration/migrators.py", line 235, in migrate_many
    result = migrator.__class__.migrate_many(migrator, target, migrations, database)
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/south/migration/migrators.py", line 310, in migrate_many
    result = self.migrate(migration, database)
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/south/migration/migrators.py", line 133, in migrate
    result = self.run(migration)
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/south/migration/migrators.py", line 107, in run
    return self.run_migration(migration)
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/south/migration/migrators.py", line 81, in run_migration
    migration_function()
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/south/migration/migrators.py", line 57, in <lambda>
    return (lambda: direction(orm))
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellow/jellow/apps/collect_data/migrations/0010_auto__chg_field_rating_tags__chg_field_rating_support__chg_field_ratin.py", line 13, in forwards
    db.alter_column('collect_data_rating', 'tags', self.gf('django.db.models.fields.IntegerField')())
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/south/db/generic.py", line 44, in _cache_clear
    return func(self, table, *args, **opts)
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/south/db/generic.py", line 522, in alter_column
    flatten(values),
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/south/db/generic.py", line 273, in execute
    cursor.execute(sql, params)
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/django/db/backends/util.py", line 40, in execute
    return self.cursor.execute(sql, params)
  File "/Users/narensathiya/Documents/Documents/Jellow/Jellow/jellowenv/lib/python2.7/site-packages/django/db/backends/postgresql_psycopg2/base.py", line 52, in execute
    return self.cursor.execute(query, args)
django.db.utils.DatabaseError: column "tags" cannot be cast to type integer

任何帮助将不胜感激，并提前感谢您！

Answer 1

如果您乐意丢弃数据，可以删除该列并创建一个新列

如果您想保留数据，则需要

a）为您的新列添加不同的名称，或者 b）创建一个临时列以在转换期间保存数据

然后您需要一系列迁移

用于添加新（或临时）列的架构迁移
显式移动数据的数据迁移，执行任何所需的转换（例如“A” - > 1）
可能是删除临时列的架构迁移

Answer 2

您需要添加“USING（col_name :: integer）”来消除此错误。但在这种情况下，您必须使用直接查询。

migrateEngine.execute（'ALTER TABLE test ALTER COLUMN testScore TYPE INTEGER using testScore :: integer'）

“无法转换为类型整数”错误

2 个答案: