将Django项目从sqlite3后端切换到postgresql时加载datadump失败

问题描述

我目前正在使用sqlite3作为我的一个Django项目的DB。我想改变这个来使用postgresql，我想保持所有的数据不变。

I am currently using sqlite3 as the DB for one of my Django projects. I want to change this to use postgresql, and I would like to keep all the data intact.

我使用了 ./ manage.py dumpdata> ; dump.json 创建数据转储，并将我的设置更改为使用postgresql。尝试使用空数据库来执行 ./ manage.py loaddata dump.json 导致关于表不存在的错误，因此我运行 ./管理.py syncdb ，并再次尝试。这导致了这个错误：

I used ./manage.py dumpdata > dump.json to create a dump of the data, and changed my settings to use postgresql. Trying first with an empty database to do ./manage.py loaddata dump.json resulted in errors about tables not existing, so I ran ./manage.py syncdb, and tried again. That results in this error:

Problem installing fixture 'dump.json': Traceback (most recent call last):
  File "/usr/lib/python2.6/site-packages/django/core/management/commands/loaddata.py", line 163, in handle
    obj.save()
  File "/usr/lib/python2.6/site-packages/django/core/serializers/base.py", line 163, in save
    models.Model.save_base(self.object, raw=True)
  File "/usr/lib/python2.6/site-packages/django/db/models/base.py", line 495, in save_base
    rows = manager.filter(pk=pk_val)._update(values)
  File "/usr/lib/python2.6/site-packages/django/db/models/query.py", line 448, in _update
    return query.execute_sql(None)
  File "/usr/lib/python2.6/site-packages/django/db/models/sql/subqueries.py", line 124, in execute_sql
    cursor = super(UpdateQuery, self).execute_sql(result_type)
  File "/usr/lib/python2.6/site-packages/django/db/models/sql/query.py", line 2347, in execute_sql
    cursor.execute(sql, params)
  File "/usr/lib/python2.6/site-packages/django/db/backends/util.py", line 19, in execute
    return self.cursor.execute(sql, params)
IntegrityError: duplicate key value violates unique constraint "django_content_type_app_label_key"

• 这不是将数据从一个数据库移动到另一个数据库的正确方法？


• 为了安全切换DB后端，我该怎么做？ li>
  
  • Is this not the correct way to move data from one database to another?
  • What should I be doing in order to switch DB backend safely?

  推荐答案

  问题只在于你得到的内容类型定义了两次 - 一旦你做 syncdb ，然后从导出的数据中导入一次。由于您的数据库中可能还有其他项目依赖于原始内容类型定义，所以建议您保留这些内容。

  The problem is simply that you're getting the content types defined twice - once when you do syncdb, and once from the exported data you're trying to import. Since you may well have other items in your database that depend on the original content type definitions, I would recommend keeping those.

  所以运行 syncdb ，do manage.py dbshel​​l 并在您的数据库中执行 TRUNCATE django_content_type; 以删除所有新定义的内容类型。那么你不应该有任何冲突 - 在这个过程中，无论如何。

  So, after running syncdb, do manage.py dbshell and in your database do TRUNCATE django_content_type; to remove all the newly-defined content types. Then you shouldn't get any conflicts - on that part of the process, in any case.

  这篇关于将Django项目从sqlite3后端切换到postgresql时加载datadump失败的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！