django数据库错误相关问题

秒速五厘米 2022-08-08 11:45 151阅读 0赞

http://[blog.csdn.net/pipisorry/article/details/45727309][blog.csdn.net_pipisorry_article_details_45727309]

**django数据库错误相关问题**

**问题：字段修改属性发生错误**

>python manage.py makemigrations You are trying to add a non-nullable field 'price_monthly' to product without a default; we can't do that (the database needs something to populate existing rows). Please select a fix: 1) Provide a one-off default now (will be set on all existing rows) 2) Quit, and let me add a default in models.py Select an option:

\{这个可能是之前已创建了表中的一条记录，之后模型中增加了一个非空的字段，但是原来已经存在的记录没有这个值\}

>python manage.py migrate ... ... raise errorclass(errno, errorvalue)django.db.utils.ProgrammingError: (1146, "Table 'lab_data.bigdata_postgraduate_research_directions' doesn't exist")

\{这个是因为在字段中添加了blank=True或者 null=True引起的\}

>python manage.py makemigrationsYou are trying to change the nullable field 'job_title' on professor to non-nullable without a default; we can't do that (the database needs something to populate existing rows).
    Please select a fix:
     1) Provide a one-off default now (will be set on all existing rows)
     2) Ignore for now, and let me handle existing rows with NULL myself (e.g. adding a RunPython or RunSQL operation in the new migration file before the AlterField operation)
     3) Quit, and let me add a default in models.py
    Select an option:

\{这个是将模型中的null=True删除了之后产生的错误\}

**1>原因解释：**

1. The migrations system is designed so that a single migration can be applied to more than one database. For example, you could have a development version, a staging version, and one or more production versions. That's why*making* the migration is a distinct step from *applying* the migration, and why`makemgirations` can't just look at the currently active database to see that it doesn't have any rows. What if you then try to apply the migration to a database that does?

The solution in your case is simple: since there are no rows, option 1 (setting a default on all existing rows) won't do anything at all. So choose option 1, and any value you like.

\[ [Django 1.7.1 requires a Default value for field - but no entry is in database. Why?][Django 1.7.1 requires a Default value for field - but no entry is in database. Why]\]

2. Django adds a default "id" field to every model, you don't need an extra "twitbot\_id" in your model. If a surrogate primary key is all you need, forget about "twitbot\_id" because it will be a duplicate of the auto-generated "id". See[https://docs.djangoproject.com/en/dev/topics/db/models/\#automatic-primary-key-fields][https_docs.djangoproject.com_en_dev_topics_db_models_automatic-primary-key-fields]

If you add this and you already have TwitterBot objects in your database you must provide a default value to populate this column for existing rows in the database.

\[ [Can't seem to lose this error: “You are trying to add a non-nullable field”][Can_t seem to lose this error_ _You are trying to add a non-nullable field]\]

3. 如果你跟我一样是因为之前建好表a后，又创建一个表b作为a的父类，a中只有pass，那么因为表a已经创建，其中有数据，当a迁移时就会出现新表不能为null且没有指定默认值时就会出现这种错误。

**解决方案：**

1>在基类b中添加允许为空或者添加默认值，并设置b不建表（meta中的abstract = true）

class Base(models.Model):
        '''
        基类
        '''
        title = models.CharField(max_length=150, null=True)
        content = models.TextField(null=True)
        time_stamp = models.DateTimeField(auto_now_add=True, default=timezone.now())
        link = models.URLField(blank=True, verbose_name='url_link')
    
        class Meta:
            abstract = True

**Note**:DataTimeField好像与其它的不一样，不好改！

1>2>3>

删除所有migrate文件(不用移除整个文件夹)，然后重来

**问题：manytomanyfeild没有默认值**

# [django admin gives warning “Field 'X' doesn't have a default value”][django admin gives warning _Field _X_ doesn_t have a default value] #

**问题：添加元属性发生错误**

raise InternalError(errno, errorvalue)
    django.db.utils.InternalError: (1017, "Can't find file: '.\\lab_data\\people_patent_prizes.frm' (errno: 2 -No such file or directory)")

\{模型类中增加 *class*  Meta :db\_table='People'使数据库中对应的表名修改成了People，原来的表间联系可能破坏了\}  
**解决方案：**

删除所有migrate文件(不用移除整个文件夹)，然后重来

[http://blog.csdn.net/pipisorry/article/details/45727309][blog.csdn.net_pipisorry_article_details_45727309]

**问题：表中字段不存在**

"Unknown column 'name' in 'field list'"

django中创建了表professor继承了表people的字段，并且在后台可以看到，但实际在数据库中不存在（数据库中查询可看到）

**出现问题原因：**

1. model中编辑的字段没有在数据库对应的表里创建（原因可能是字段是继承自父类，出现的什么问题？）

数据库中查看表中的字段：

![Center][]

2. migration文件出了什么问题？导致没有同步到数据库（表都没创建）

**解决方案1：**

在数据库中手动添加没有创建的字段

alter table bigdata\_professor add column name varchar(6);

再次查看表中字段：

![Center 1][]

再次运行django服务器，后台添加name字段时就不会出错了。

**解决方案2：**

先删除整个migrations文件夹，再python manage.py makemigrations,再python manage.py migrate

![Center 2][]  
这样表就可以重新建立成功了！（可以查询到django中新建的表bigdata\_professor....）

![Center 3][]  
**Note**:

1. 成功后最好把之前删除的文件夹migrations重新建一个（app中的）

2. 只删除migration文件可能不会出现这个问题：

No migrations to apply.   Your models have changes that are not yet reflected in a migration, and so won't be applied. Run 'manage.py makemigrations' to make new migrations, and then re-run 'manage.py migrate' to apply them.

我了个去，都不知道为啥migration文件会出问题，删除后再操作就没事了，可能是（在makemigrations）之前先进行了migrate操作？

\[[Django Models (1054, “Unknown column in 'field list'”)][Django Models _1054_ _Unknown column in _field list]\]

**问题：表不存在或者No migrations to apply**

"Table 'lab_data.bigdata_resdir' doesn't exist"

模型中建立新表后，makemigrations成功，但是migrate出现错误:

python manage.py migrate Operations to ...: Apply all migrations: ...
    No migrations to apply.(即使实际上明明makemigrations成功，并且有许多migrations可以应用)
      Your models have changes that are not yet reflected in a migration, and so won't be applied.  Run 'manage.py makemigrations' to make new migrations, and then re-run 'manage.py migrate' to apply them.

按照提示重新makemigration后migration文件就不会创建新表了，在数据库中表也的确没有新建。

**原因：**

1. Sounds like your initial migration was faked because the table already existed (probably with an outdated schema):

[https://docs.djangoproject.com/en/1.7/topics/migrations/\#adding-migrations-to-apps][https_docs.djangoproject.com_en_1.7_topics_migrations_adding-migrations-to-apps]

"This will make a new initial migration for your app. Now, when you run migrate,**Django will detect that you have an initial migration and that the tables it wants to create already exist, and will mark the migration as already applied**."

Otherwise you would get an no-such-table error.

\[[No migrations to apply, even though there are migrations to apply][No migrations to apply_ even though there are migrations to apply]\]

2. 也可能是之前按照某个说明执行了一次`python manage.py migrate --fake`导致的。`--fake` 的含义是不执行该迁移脚本但是标记该脚本已经被执行过。导致之后无法正常进行迁移。

\[[Django 1.7 中 migrate 无法执行而且表不存在的解决方案][Django 1.7 _ migrate]\]

**解决方案：**

方法1.

1> In MySQL Database delete row `'app_name'` from the table `'django_migrations'`.

打开mysql command line client, 进入创建好的数据库use databasename; 查看表select \* from django\_migration; 发现将要执行的迁移脚本的 id 已经添加在表中了，将其删除即可，即删除最新一次app\_name对就的id行。

![Center 4][]

2> Delete all migration files in migrations folder.

3> Try again `python manage.py makemigrations` and `python manage.py migrate` command.

\[[Django 1.7 - “No migrations to apply” when run migrate after makemigrations][Django 1.7 - _No migrations to apply_ when run migrate after makemigrations]\]

方法2：

移除整个migrations文件夹，重新makemigrations和migrate。之后就会自动创建了：

![Center 5][]

方法3：

实在不行，只能drop database，再重新建立了。

[http://blog.csdn.net/pipisorry/article/details/45727309][blog.csdn.net_pipisorry_article_details_45727309]

**问题：外键修改成多对多错误**

ValueError: Cannot alter field bigdata.Postgraduate.publisher into bigdata.Postgraduate.publisher - they are not compatible types (you cannot alter to or from M2M fields
    , or add or remove through= on M2M fields)

\{这个错误是由将模型Postgraduate中的publisher字段从ForeignKey修改成ManyToManyField引起的\}

**解决方案：**

删除所有migrations文件，重新makemigrations和migrate

\[foreignkey error: [ Django migration error :you cannot alter to or from M2M fields, or add or remove through= on M2M fields][Django migration error _you cannot alter to or from M2M fields_ or add or remove through_ on M2M fields]\]

**数据库注册到site管理错误**

TypeError: \_\_init\_\_() missing 2 required positional arguments : 'model' and 'admin\_site'

class DirectionsInline(inlineBase, admin.ModelAdmin):
        model = Directions
        inlines = [ImagesInline, ]
    admin.site.register(Directions, DirectionsInline)

**解决**：原因可能是继承admin.ModelAdmin的类中不能有model = \*\*\*

**数据库权限错误**

**django.db.utils.operationalerror:<1045,"access denied for user root@localhost using password yes>**

**解决方案**1：django setting.py文件中设置的database用户名或者密码错了，修改一下就可以了

或者是django运行项目时用的不是settings.py文件，这个在os.environ.setdefault("DJANGO\_SETTINGS\_MODULE", "labsite.settings")中设置

**其它方案**：[  
][Link 1]

[Access denied for user 'root'@'localhost' (using password: YES)][Access_denied_for_user_root_localhost_using_password_YES]

[mysql Access denied for user root@localhost错误解决方法总结(转)][Link 1]

[ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)][ERROR 1045 _28000_ Access denied for user _root_localhost_ _using password_ NO]

[MySQL Forums][] ::[Install & Repo][Install _ Repo] ::[ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)][ERROR 1045 _28000_ Access denied for user _root_localhost_ _using password_ NO 1]

**django.db.utils.operationalerror:<2003, "can't connect to mysql server on '127.0.0.1'(winerror 10061\] No connection could be made because the target machine actively refused it)")**

settings.py中设置的host和port如下

'HOST': '127.0.0.1','PORT': '3306'

如改动port为其它，可能导致该问题

**其它问题：**

1.[Error: Tablespace for table xxx exists. Please DISCARD the tablespace before IMPORT][Error_ Tablespace for table xxx exists. Please DISCARD the tablespace before IMPORT]

2. django.db.utils.ProgrammingError: (1146, "Table 'lab\_data.django\_migrations' doesn't exist")

3.django.db.utils.InternalError: (1050, "Table '\`l ab\_data\`.\`django\_migrations\`'already exists")

1>两个模型的数据库表名设置成一样的了

class Meta:
        db_table = 'WorkExp1'

2>python manage.py migrate --fake

from: [http://blog.csdn.net/pipisorry/article/details/45727309][blog.csdn.net_pipisorry_article_details_45727309]

ref:\[[Django 问题收集][Django]\]

[blog.csdn.net_pipisorry_article_details_45727309]: http://blog.csdn.net/pipisorry/article/details/45727309
[Django 1.7.1 requires a Default value for field - but no entry is in database. Why]: http://stackoverflow.com/questions/26988552/django-1-7-1-requires-a-default-value-for-field-but-no-entry-is-in-database-w
[https_docs.djangoproject.com_en_dev_topics_db_models_automatic-primary-key-fields]: https://docs.djangoproject.com/en/dev/topics/db/models/#automatic-primary-key-fields
[Can_t seem to lose this error_ _You are trying to add a non-nullable field]: http://stackoverflow.com/questions/26558261/cant-seem-to-lose-this-error-you-are-trying-to-add-a-non-nullable-field
[django admin gives warning _Field _X_ doesn_t have a default value]: http://stackoverflow.com/questions/4577832/django-admin-gives-warning-field-x-doesnt-have-a-default-value
[Center]: /images/20220805/cb11a373e72946cc85aec8b93925a19a.png
[Center 1]: /images/20220805/7598e9938f3d40b09a3abaf3afb007db.png
[Center 2]: /images/20220805/bb511b1dfabc4970ae07ef06760b08cd.png
[Center 3]: /images/20220805/14e1843fb652416abc4cbc73c0f019cc.png
[Django Models _1054_ _Unknown column in _field list]: http://stackoverflow.com/questions/3787237/django-models-1054-unknown-column-in-field-list
[https_docs.djangoproject.com_en_1.7_topics_migrations_adding-migrations-to-apps]: https://docs.djangoproject.com/en/1.7/topics/migrations/#adding-migrations-to-apps
[No migrations to apply_ even though there are migrations to apply]: http://stackoverflow.com/questions/26405939/no-migrations-to-apply-even-though-there-are-migrations-to-apply
[Django 1.7 _ migrate]: http://gerhut.me/django-1-7-zhong-migrate-wu-fa-zhi-xing-er-qie-biao-bu-cun-zai-de-jie-jue-fang-an/
[Center 4]: /images/20220805/dfe7aa01cb3a4c05baf197d4e24c4b82.png
[Django 1.7 - _No migrations to apply_ when run migrate after makemigrations]: http://stackoverflow.com/questions/25958708/django-1-7-no-migrations-to-apply-when-run-migrate-after-makemigrations
[Center 5]: /images/20220805/ebde39bdcbc74c21936997d75d549485.png
[Django migration error _you cannot alter to or from M2M fields_ or add or remove through_ on M2M fields]: http://stackoverflow.com/questions/26927705/django-migration-error-you-cannot-alter-to-or-from-m2m-fields-or-add-or-remove
[Link 1]: http://www.cnblogs.com/qq78292959/p/3641972.html
[Access_denied_for_user_root_localhost_using_password_YES]: http://blog.sina.com.cn/s/blog_65a268b90100m1mw.html
[ERROR 1045 _28000_ Access denied for user _root_localhost_ _using password_ NO]: http://www.cnblogs.com/khler/archive/2011/02/10/1950819.html
[MySQL Forums]: http://forums.mysql.com/index.php
[Install _ Repo]: http://forums.mysql.com/list.php?11
[ERROR 1045 _28000_ Access denied for user _root_localhost_ _using password_ NO 1]: http://forums.mysql.com/read.php?11,34014,34014#msg-34014
[Error_ Tablespace for table xxx exists. Please DISCARD the tablespace before IMPORT]: http://stackoverflow.com/questions/15694168/error-tablespace-for-table-xxx-exists-please-discard-the-tablespace-before-imp
[Django]: http://blog.csdn.net/dale_dede/article/details/45697879