Django遷移ProgrammingError：語法錯誤在「」

我正在學習django（1.9.2）在練習網站和postgresql數據庫與psycopg2。我用某個屬性「預覽」定義了一個模型，後來完全刪除了該屬性。儘管刪除了它，django似乎是從緩存或其他東西引用舊的定義。 makemigrations命令似乎工作正常，反映了我對模型定義所做的每一個更改，但是一旦我運行migrate命令，則會彈出此錯誤。Django遷移ProgrammingError：語法錯誤在「」

(env) D:\Web Workspace\Rat Race Website\ratrace>python manage.py migrate 
Operations to perform: 
    Apply all migrations: contenttypes, news, polls, auth, sessions, admin 
Running migrations: 
    Applying news.0003_auto_20160212_1209...Traceback (most recent call last): 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\db\backen 
ds\utils.py", line 64, in execute 
    return self.cursor.execute(sql, params) 
psycopg2.ProgrammingError: syntax error at or near "9999999999999" 
LINE 1: ...ER TABLE "news_news" ADD COLUMN "preview" varchar(9999999999... 
                  ^


The above exception was the direct cause of the following exception: 

Traceback (most recent call last): 
    File "manage.py", line 10, in <module> 
    execute_from_command_line(sys.argv) 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\core\mana 
gement\__init__.py", line 353, in execute_from_command_line 
    utility.execute() 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\core\mana 
gement\__init__.py", line 345, in execute 
    self.fetch_command(subcommand).run_from_argv(self.argv) 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\core\mana 
gement\base.py", line 348, in run_from_argv 
    self.execute(*args, **cmd_options) 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\core\mana 
gement\base.py", line 399, in execute 
    output = self.handle(*args, **options) 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\core\mana 
gement\commands\migrate.py", line 200, in handle 
    executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial) 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\db\migrat 
ions\executor.py", line 92, in migrate 
    self._migrate_all_forwards(plan, full_plan, fake=fake, fake_initial=fake_ini 
tial) 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\db\migrat 
ions\executor.py", line 121, in _migrate_all_forwards 
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_ 
initial) 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\db\migrat 
ions\executor.py", line 198, in apply_migration 
    state = migration.apply(state, schema_editor) 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\db\migrat 
ions\migration.py", line 123, in apply 
    operation.database_forwards(self.app_label, schema_editor, old_state, projec 
t_state) 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\db\migrat 
ions\operations\fields.py", line 62, in database_forwards 
    field, 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\db\backen 
ds\base\schema.py", line 396, in add_field 
    self.execute(sql, params) 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\db\backen 
ds\base\schema.py", line 110, in execute 
    cursor.execute(sql, params) 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\db\backen 
ds\utils.py", line 79, in execute 
    return super(CursorDebugWrapper, self).execute(sql, params) 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\db\backen 
ds\utils.py", line 64, in execute 
    return self.cursor.execute(sql, params) 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\db\utils. 
py", line 95, in __exit__ 
    six.reraise(dj_exc_type, dj_exc_value, traceback) 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\utils\six 
.py", line 685, in reraise 
    raise value.with_traceback(tb) 
    File "D:\Web Workspace\Rat Race Website\env\lib\site-packages\django\db\backen 
ds\utils.py", line 64, in execute 
    return self.cursor.execute(sql, params) 
django.db.utils.ProgrammingError: syntax error at or near "9999999999999" 
LINE 1: ...ER TABLE "news_news" ADD COLUMN "preview" varchar(9999999999...

數據庫表是空的，所以我懷疑，刪除數據庫，使一個新的可能解決這個問題，現在，但我想如果它在未來，再次發生了更具體的解決方案刪除數據庫不是一個選項。

以下是模型定義的外觀。

from django.db import models 

# Create your models here. 
class News(models.Model): 
    headline = models.CharField(max_length=100) 
    content = models.CharField(max_length=100) 
    pub_date = models.DateTimeField('date published') 
    content_preview = models.CharField(max_length=100, blank=True) 
    thumbnail = models.ImageField(upload_to='thumbnails/%Y/%m/%d/', blank=True) 
    def __str__(self): 
     return self.headline

沒有「預覽」屬性了，但Django似乎沒有得到。

編輯：下面是預覽場

preview = CharField(max_length=9999999999999)

定義它產生一個錯誤，說這不可能是空的，所以我進入了一個時間默認值爲"news preview"。我假設默認值是針對現有條目的。當時有大約5個測試條目。只需閱讀另一篇文章，即在輸入一次默認值時使用的引號是導致問題的可能原因。關於psycopg2不喜歡引用值的東西？...這是一個字符串值，所以我認爲我需要引號。

不管怎樣，現在我已經清除了預覽字段，我該如何讓django忘記它曾經存在？

來源

2016-02-12 Khalifa Abbas Lame

嘗試添加列時似乎失敗，這可能是您之前沒有運行的遷移。預覽字段的定義是什麼？ – cdvv7788

剛剛添加到這個問題。這有幫助嗎？ –

您需要修改您的遷移（編輯它們或刪除/重新創建）。不過，我認爲場地的長度可能是原因。我可以檢查一下。 – cdvv7788

去掉其他評論和我自己的經驗。。。當出現此錯誤時，請進入您的遷移文件夾並刪除除__init__.py之外的所有內容。您甚至可以刪除__pycache__文件夾。然後再次運行makemigrations和migrate。我認爲應該解決這個問題。

來源

2016-02-12 17:42:46 laurenll

Django遷移ProgrammingError：語法錯誤在「」

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