# Django 2.2.9.dev20191202104323 文档

# 系统检查框架

系统检查框架是一组验证Django项目的静态检查。 它检测到常见的问题，并提供了如何解决这些问题的提示。 该框架是可扩展的，所以你可以轻松地添加自己的检查。

有关如何添加自己的检查并将其与 Django 的系统检查集成的详细信息，请参阅：doc：系统检查主题指南</topics/checks>。

## API 参考

### “CheckMessage”

class `CheckMessage`(level, msg, hint=None, obj=None, id=None)

系统检查提出的警告和错误必须是“CheckMessage”的实例。 一个实例封装了一个可报告的错误或警告。 它还提供适用于消息的上下文和提示以及用于过滤目的的唯一标识符。

构造方法的参数：

`level`
  消息的严重性。 使用其中一个预定义的值：DEBUG，INFO，WARNING，ERROR，CRITICAL。 如果级别大于或等于“ERROR”，则Django将阻止执行管理命令。 级别低于“ERROR”的消息（即警告）被报告给控制台，但是可以被静默。
`msg`
  用来描述问题的一个简短字符串(少于80个字符)。这个字符串不应该包含换行符。
`hint`
  提供解决问题的提示的单行字符串。 如果不能提供提示，或者错误消息中的提示是显而易见的，则提示可以省略，或者可以使用“None”的值。
`obj`
  Optional. An object providing context for the message (for example, the model where the problem was discovered). The object should be a model, field, or manager or any other object that defines a `__str__()` method. The method is used while reporting all messages and its result precedes the message.
`id`
  Optional string. A unique identifier for the issue. Identifiers should follow the pattern `applabel.X001`, where `X` is one of the letters `CEWID`, indicating the message severity (`C` for criticals, `E` for errors and so). The number can be allocated by the application, but should be unique within that application.

有一些子类可以使创建通用级别的消息更简单。 当使用它们时，可以省略“level”参数，因为它是由类名所隐含的。

class `Debug`(msg, hint=None, obj=None, id=None)

class `Info`(msg, hint=None, obj=None, id=None)

class `Warning`(msg, hint=None obj=None, id=None)

class `Error`(msg, hint=None, obj=None, id=None)

class `Critical`(msg, hint=None, obj=None, id=None)

## 内置标签

Django 的系统检查按以下标签组织：

- `admin`：检查所有后台站点申明。
- `caches`：检查缓存相关的配置。
- `compatibility`：标记版本升级可能导致的问题。
- `database`: Checks database-related configuration issues. Database checks are not run by default because they do more than static code analysis as regular checks do. They are only run by the `migrate` command or if you specify the `database` tag when calling the `check` command.
- `models`：检查模型，字段和管理器定义。
- `security`：检查安全相关配置。
- `signals`：检查信号申明和处理器注册信息。
- `staticfiles`：检查 `django.contrib.staticfiles` 配置。
- `templates`：检查模板相关配置。
- `translation`：检查翻译相关配置。
- `urls`：检查 URL 配置。

一些可能通过多个标签同时注册的检查项。

## 核心系统检查

### 向后兼容

兼容性检查警告那些升级 Django 后可能出现的问题。

- 2_0.W001: Your URL pattern `<pattern>` has a `route` that contains `(?P<`, begins with a `^`, or ends with a `$`. This was likely an oversight when migrating from `url()` to `path()`.

### 缓存

The following checks verify that your `CACHES` setting is correctly configured:

- caches.E001: You must define a `'default'` cache in your `CACHES` setting.

### 数据库

#### MySQL

如果您使用MySQL，需要执行以下检查：

- mysql.E001: MySQL does not allow unique `CharField`s to have a `max_length` > 255.
- mysql.W002: MySQL Strict Mode is not set for database connection '<alias>'. See also Setting sql_mode.

### 模型字段

- fields.E001: 字段名不能已下划线结尾。
- fields.E002: 字段名不能有 `"__"`.
- fields.E003*: `pk` 是保留关键字，不能作为字段名使用。
- ** fields.E004 **：“choices”必须是可迭代的（例如，列表或元组）。
- ** fields.E005 **：``choices``必须是一个可返回的``（实际值，易读的名称）``构成元组。
- ** fields.E006 **：`db_index``必须是`None`，``True``或`False`。
- ** fields.E007 **：主键不能有“null = True”。
- fields.E008：所有 `validators` 必须都是可调用的。
- fields.E100： `AutoField`` 必须设置 primary_key=True。
- fields.E110: `BooleanField`s do not accept null values. This check appeared before support for null values was added in Django 2.1.
- fields.E120： `CharField` 必须定义一个 `max_length` 属性。
- fields.E121： `max_length` 必须是个正整数。
- fields.W122： `max_length` 在使用 `<integer field type>` 时会被忽略。
- fields.E130： `DecimalField` 必须定义一个 `decimal_places` 属性。
- fields.E131： `decimal_places` 必须是个非负整数。
- fields.E132： `DecimalField` 必须定义一个 `max_digits` 属性。
- fields.E133： `max_digits` 必须是一个非负整数。
- fields.E134： `max_digits` 必须大于或等于 `decimal_places`。
- fields.E140： `FilePathField` 的 `allow_files` 或 `allow_folders` 必须有一个被设为 True。
- fields.E150： 若``GenericIPAddressField`` 不允许 null 值，那么它也不接受空值，因为空值被保存为 null。
- fields.E160: The options `auto_now`, `auto_now_add`, and `default` are mutually exclusive. Only one of these options may be present.
- fields.W161：默认绑定值。
- fields.W162： `<database>` 并不支持在 `<field data type>` 列上创建数据库索引。
- fields.E900: `IPAddressField` has been removed except for support in historical migrations.
- fields.W900: `IPAddressField` has been deprecated. Support for it (except in historical migrations) will be removed in Django 1.9. This check appeared in Django 1.7 and 1.8.
- fields.W901: `CommaSeparatedIntegerField` has been deprecated. Support for it (except in historical migrations) will be removed in Django 2.0. This check appeared in Django 1.10 and 1.11.
- fields.E901: `CommaSeparatedIntegerField` is removed except for support in historical migrations.
- fields.W902: `FloatRangeField` is deprecated and will be removed in Django 3.1.

#### 文件字段

- fields.E200: `unique` is not a valid argument for a `FileField`. This check is removed in Django 1.11.
- fields.E201： `primary_key` 对于 `FileField` 来说不是个有效的参数。
- fields.E202： `FileField` 的 `upload_to` 参数必须是个相对路径，而不是一个相对路径。
- fields.E210： 不能使用 `ImageField`，因为未安装 Pillow。

#### 关联字段

- fields.E300: Field defines a relation with model `<model>`, which is either not installed, or is abstract.
- fields.E301: Field defines a relation with the model `<model>` which has been swapped out.
- fields.E302: Accessor for field `<field name>` clashes with field `<field name>`.
- fields.E303: Reverse query name for field `<field name>` clashes with field `<field name>`.
- fields.E304: Field name `<field name>` clashes with accessor for `<field name>`.
- fields.E305: Field name `<field name>` clashes with reverse query name for `<field name>`.
- fields.E306: Related name must be a valid Python identifier or end with a `'+'`.
- fields.E307: The field `<app label>.<model>.<field name>` was declared with a lazy reference to `<app label>.<model>`, but app `<app label>` isn't installed or doesn't provide model `<model>`.
- fields.E308: Reverse query name `<related query name>` must not end with an underscore.
- fields.E309: Reverse query name `<related query name>` must not contain `'__'`.
- fields.E310: No subset of the fields `<field1>`, `<field2>`, ... on model `<model>` is unique. Add `unique=True` on any of those fields or add at least a subset of them to a unique_together constraint.
- fields.E311: `<model>` must set `unique=True` because it is referenced by a `ForeignKey`.
- fields.E312: The `to_field` `<field name>` doesn't exist on the related model `<app label>.<model>`.
- fields.E320: Field specifies `on_delete=SET_NULL`, but cannot be null.
- fields.E321: The field specifies `on_delete=SET_DEFAULT`, but has no default value.
- fields.E330: `ManyToManyField`s cannot be unique.
- fields.E331: Field specifies a many-to-many relation through model `<model>`, which has not been installed.
- fields.E332: Many-to-many fields with intermediate tables must not be symmetrical.
- fields.E333: The model is used as an intermediate model by `<model>`, but it has more than two foreign keys to `<model>`, which is ambiguous. You must specify which two foreign keys Django should use via the `through_fields` keyword argument.
- fields.E334: The model is used as an intermediate model by `<model>`, but it has more than one foreign key from `<model>`, which is ambiguous. You must specify which foreign key Django should use via the `through_fields` keyword argument.
- fields.E335: The model is used as an intermediate model by `<model>`, but it has more than one foreign key to `<model>`, which is ambiguous. You must specify which foreign key Django should use via the `through_fields` keyword argument.
- fields.E336: The model is used as an intermediary model by `<model>`, but it does not have foreign key to `<model>` or `<model>`.
- fields.E337: Field specifies `through_fields` but does not provide the names of the two link fields that should be used for the relation through `<model>`.
- fields.E338: The intermediary model `<through model>` has no field `<field name>`.
- fields.E339: `<model>.<field name>` is not a foreign key to `<model>`.
- fields.E340: The field's intermediary table `<table name>` clashes with the table name of `<model>`/`<model>.<field name>`.
- fields.W340: `null` has no effect on `ManyToManyField`.
- fields.W341: `ManyToManyField` does not support `validators`.
- fields.W342: Setting `unique=True` on a `ForeignKey` has the same effect as using a `OneToOneField`.
- fields.W343: `limit_choices_to` has no effect on `ManyToManyField` with a `through` model.

### 模型

- models.E001： `<swappable>` 不是表单 `app_label.app_name`。
- models.E002: `<SETTING>` references `<model>`, which has not been installed, or is abstract.
- models.E003: The model has two identical many-to-many relations through the intermediate model `<app_label>.<model>`.
- models.E004: `id` can only be used as a field name if the field also sets `primary_key=True`.
- models.E005: The field `<field name>` from parent model `<model>` clashes with the field `<field name>` from parent model `<model>`.
- models.E006：与另一个模型 `<model>` 的字段 `<field name>` 冲突的字段。
- models.E007： 列名 `<column name>` 被其它字段使用的字段 `<field name>` 。
- models.E008： `index_together` 必须是个列表或元组。
- models.E009： 所有 `index_together` 元素都必须是列表或元组。
- models.E010： `unique_together` 必须是个列表或元组。
- models.E011： 所有 `unique_together` 元素都必须是列表或元组。
- models.E012： `indexes/index_together/unique_together` 指向了不存在的字段 `<field name>`。
- models.E013： `indexes/index_together/unique_together` 指向一个 `ManyToManyField` `<field name>`，但此选项不支持 `ManyToManyField`。
- models.E014： `ordering` 必须是个元组或列表（即便你只想按照一个字段进行排序）。
- models.E015： `ordering` 指向了不存在的字段 `<field name>`。
- models.E016: `indexes/index_together/unique_together` refers to field `<field_name>` which is not local to model `<model>`.
- models.E017: Proxy model `<model>` contains model fields.
- models.E018: Autogenerated column name too long for field `<field>`. Maximum length is `<maximum length>` for database `<alias>`.
- models.E019: Autogenerated column name too long for M2M field `<M2M field>`. Maximum length is `<maximum length>` for database `<alias>`.
- models.E020: The `<model>.check()` class method is currently overridden.
- models.E021: `ordering` and `order_with_respect_to` cannot be used together.
- models.E022: `<function>` contains a lazy reference to `<app label>.<model>`, but app `<app label>` isn't installed or doesn't provide model `<model>`.
- models.E023: The model name `<model>` cannot start or end with an underscore as it collides with the query lookup syntax.
- models.E024: The model name `<model>` cannot contain double underscores as it collides with the query lookup syntax.
- models.E025: The property `<property name>` clashes with a related field accessor.
- models.E026: The model cannot have more than one field with `primary_key=True`.
- models.W027: `<database>` does not support check constraints.
- models.E028: `db_table` `<db_table>` is used by multiple models: `<model list>`.
- models.W035: `db_table` `<db_table>` is used by multiple models: `<model list>`.

### 安全

The security checks do not make your site secure. They do not audit code, do intrusion detection, or do anything particularly complex. Rather, they help perform an automated, low-hanging-fruit checklist. They help you remember the simple things that improve your site's security.

Some of these checks may not be appropriate for your particular deployment configuration. For instance, if you do your HTTP to HTTPS redirection in a load balancer, it'd be irritating to be constantly warned about not having enabled `SECURE_SSL_REDIRECT`. Use `SILENCED_SYSTEM_CHECKS` to silence unneeded checks.

The following checks are run if you use the `check --deploy` option:

- security.W001: You do not have `django.middleware.security.SecurityMiddleware` in your `MIDDLEWARE` so the `SECURE_HSTS_SECONDS`, `SECURE_CONTENT_TYPE_NOSNIFF`, `SECURE_BROWSER_XSS_FILTER`, and `SECURE_SSL_REDIRECT` settings will have no effect.
- security.W002: You do not have `django.middleware.clickjacking.XFrameOptionsMiddleware` in your `MIDDLEWARE`, so your pages will not be served with an `'x-frame-options'` header. Unless there is a good reason for your site to be served in a frame, you should consider enabling this header to help prevent clickjacking attacks.
- security.W003: You don't appear to be using Django's built-in cross-site request forgery protection via the middleware (`django.middleware.csrf.CsrfViewMiddleware` is not in your `MIDDLEWARE`). Enabling the middleware is the safest approach to ensure you don't leave any holes.
- security.W004: You have not set a value for the `SECURE_HSTS_SECONDS` setting. If your entire site is served only over SSL, you may want to consider setting a value and enabling HTTP Strict Transport Security. Be sure to read the documentation first; enabling HSTS carelessly can cause serious, irreversible problems.
- security.W005: You have not set the `SECURE_HSTS_INCLUDE_SUBDOMAINS` setting to `True`. Without this, your site is potentially vulnerable to attack via an insecure connection to a subdomain. Only set this to `True` if you are certain that all subdomains of your domain should be served exclusively via SSL.
- security.W006: Your `SECURE_CONTENT_TYPE_NOSNIFF` setting is not set to `True`, so your pages will not be served with an `'X-Content-Type-Options: nosniff'` header. You should consider enabling this header to prevent the browser from identifying content types incorrectly.
- security.W007: Your `SECURE_BROWSER_XSS_FILTER` setting is not set to `True`, so your pages will not be served with an `'X-XSS-Protection: 1; mode=block'` header. You should consider enabling this header to activate the browser's XSS filtering and help prevent XSS attacks.
- security.W008: Your `SECURE_SSL_REDIRECT` setting is not set to `True`. Unless your site should be available over both SSL and non-SSL connections, you may want to either set this setting to `True` or configure a load balancer or reverse-proxy server to redirect all connections to HTTPS.
- security.W009: Your `SECRET_KEY` has less than 50 characters or less than 5 unique characters. Please generate a long and random `SECRET_KEY`, otherwise many of Django's security-critical features will be vulnerable to attack.
- security.W010: You have `django.contrib.sessions` in your `INSTALLED_APPS` but you have not set `SESSION_COOKIE_SECURE` to `True`. Using a secure-only session cookie makes it more difficult for network traffic sniffers to hijack user sessions.
- security.W011: You have `django.contrib.sessions.middleware.SessionMiddleware` in your `MIDDLEWARE`, but you have not set `SESSION_COOKIE_SECURE` to `True`. Using a secure-only session cookie makes it more difficult for network traffic sniffers to hijack user sessions.
- security.W012: `SESSION_COOKIE_SECURE` is not set to `True`. Using a secure-only session cookie makes it more difficult for network traffic sniffers to hijack user sessions.
- security.W013: You have `django.contrib.sessions` in your `INSTALLED_APPS`, but you have not set `SESSION_COOKIE_HTTPONLY` to `True`. Using an `HttpOnly` session cookie makes it more difficult for cross-site scripting attacks to hijack user sessions.
- security.W014: You have `django.contrib.sessions.middleware.SessionMiddleware` in your `MIDDLEWARE`, but you have not set `SESSION_COOKIE_HTTPONLY` to `True`. Using an `HttpOnly` session cookie makes it more difficult for cross-site scripting attacks to hijack user sessions.
- security.W015: `SESSION_COOKIE_HTTPONLY` is not set to `True`. Using an `HttpOnly` session cookie makes it more difficult for cross-site scripting attacks to hijack user sessions.
- security.W016: `CSRF_COOKIE_SECURE` is not set to `True`. Using a secure-only CSRF cookie makes it more difficult for network traffic sniffers to steal the CSRF token.
- security.W017: `CSRF_COOKIE_HTTPONLY` is not set to `True`. Using an `HttpOnly` CSRF cookie makes it more difficult for cross-site scripting attacks to steal the CSRF token. This check is removed in Django 1.11 as the `CSRF_COOKIE_HTTPONLY` setting offers no pratical benefit.
- security.W018: You should not have `DEBUG` set to `True` in deployment.
- security.W019: You have `django.middleware.clickjacking.XFrameOptionsMiddleware` in your `MIDDLEWARE`, but `X_FRAME_OPTIONS` is not set to `'DENY'`. The default is `'SAMEORIGIN'`, but unless there is a good reason for your site to serve other parts of itself in a frame, you should change it to `'DENY'`.
- security.W020: `ALLOWED_HOSTS` must not be empty in deployment.
- security.W021: You have not set the `SECURE_HSTS_PRELOAD` setting to `True`. Without this, your site cannot be submitted to the browser preload list.

### 信号

- signals.E001: `<handler>` was connected to the `<signal>` signal with a lazy reference to the sender `<app label>.<model>`, but app `<app label>` isn't installed or doesn't provide model `<model>`.

### 模板

The following checks verify that your `TEMPLATES` setting is correctly configured:

- templates.E001: You have `'APP_DIRS': True` in your `TEMPLATES` but also specify `'loaders'` in `OPTIONS`. Either remove `APP_DIRS` or remove the `'loaders'` option.
- templates.E002: `string_if_invalid` in `TEMPLATES` `OPTIONS` must be a string but got: `{value}` (`{type}`).

### 翻译

The following checks are performed on your translation configuration:

- translation.E001: You have provided an invalid value for the `LANGUAGE_CODE` setting.

### URLs

以下检查项针对你的 URL 配置执行：

- urls.W001: Your URL pattern `<pattern>` uses `include()` with a `route` ending with a `$`. Remove the dollar from the `route` to avoid problems including URLs.
- urls.W002: Your URL pattern `<pattern>` has a `route` beginning with a `/`. Remove this slash as it is unnecessary. If this pattern is targeted in an `include()`, ensure the `include()` pattern has a trailing `/`.
- urls.W003: Your URL pattern `<pattern>` has a `name` including a `:`. Remove the colon, to avoid ambiguous namespace references.
- urls.E004: Your URL pattern `<pattern>` is invalid. Ensure that `urlpatterns` is a list of `path()` and/or `re_path()` instances.
- urls.W005: URL namespace `<namespace>` isn't unique. You may not be able to reverse all URLs in this namespace.
- urls.E006: The `MEDIA_URL`/ `STATIC_URL` setting must end with a slash.
- urls.E007: The custom `handlerXXX` view `'path.to.view'` does not take the correct number of arguments (…).
- urls.E008: The custom `handlerXXX` view `'path.to.view'` could not be imported.

## `contrib` 应用检查

### `admin`

后台检查项均作为 `admin` 标签的一部分执行。

以下检查项在每个通过后台站点注册的 `ModelAdmin` （或其子类）上执行。

- admin.E001： `raw_id_fields` 的值必须是个列表或元组。
- admin.E002： `raw_id_fields[n]` 的值指向 `<field name>`，它并不是 `<model>` 的属性。
- admin.E003： `raw_id_fields[n]` 的值必须是个外键或一个多对多字段。
- admin.E004： `fields` 的值必须是列表或元组。
- admin.E005： `fieldsets` 和 `fields` 都是定制的。
- admin.E006： `fields` 的值包含了重复字段。
- admin.E007： `fieldsets` 的值必须是个列表或元组。
- admin.E008： `fieldsets[n]` 的值必须是个列表或元组。
- admin.E009： `fieldsets[n]` 的值的长度必须是 2。
- admin.E010： `fieldsets[n][1]` 的值必须是个字典。
- admin.E011： `fieldsets[n][1]` 的值必须包含键 `fields`。
- admin.E012： `fieldsets[n][1]` 中有重复字段。
- admin.E013: `fields[n]/fieldsets[n][m]` cannot include the `ManyToManyField` `<field name>`, because that field manually specifies a relationship model.
- admin.E014： `exclude` 的值必须是个列表或元组。
- admin.E015： `exclude` 的值必须包含重复字段。
- admin.E016： `form` 的值必须继承自 `BaseModelForm`。
- admin.E017： `filter_vertical` 的值必须是个列表或元组。
- admin.E018： `filter_horizontal` 的值必须是个列表或元组。
- admin.E019: The value of `filter_vertical[n]/filter_vertical[n]` refers to `<field name>`, which is not an attribute of `<model>`.
- admin.E020: The value of `filter_vertical[n]/filter_vertical[n]` must be a many-to-many field.
- admin.E021: The value of `radio_fields` must be a dictionary.
- admin.E022: The value of `radio_fields` refers to `<field name>`, which is not an attribute of `<model>`.
- admin.E023: The value of `radio_fields` refers to `<field name>`, which is not a `ForeignKey`, and does not have a `choices` definition.
- admin.E024: The value of `radio_fields[<field name>]` must be either `admin.HORIZONTAL` or `admin.VERTICAL`.
- admin.E025: The value of `view_on_site` must be either a callable or a boolean value.
- admin.E026: The value of `prepopulated_fields` must be a dictionary.
- admin.E027: The value of `prepopulated_fields` refers to `<field name>`, which is not an attribute of `<model>`.
- admin.E028: The value of `prepopulated_fields` refers to `<field name>`, which must not be a `DateTimeField`, a `ForeignKey`, a `OneToOneField`, or a `ManyToManyField` field.
- admin.E029: The value of `prepopulated_fields[<field name>]` must be a list or tuple.
- admin.E030: The value of `prepopulated_fields` refers to `<field name>`, which is not an attribute of `<model>`.
- admin.E031: The value of `ordering` must be a list or tuple.
- admin.E032: The value of `ordering` has the random ordering marker `?`, but contains other fields as well.
- admin.E033: The value of `ordering` refers to `<field name>`, which is not an attribute of `<model>`.
- admin.E034: The value of `readonly_fields` must be a list or tuple.
- admin.E035: The value of `readonly_fields[n]` is not a callable, an attribute of `<ModelAdmin class>`, or an attribute of `<model>`.
- admin.E036: The value of `autocomplete_fields` must be a list or tuple.
- admin.E037: The value of `autocomplete_fields[n]` refers to `<field name>`, which is not an attribute of `<model>`.
- admin.E038: The value of `autocomplete_fields[n]` must be a foreign key or a many-to-many field.
- admin.E039: An admin for model `<model>` has to be registered to be referenced by `<modeladmin>.autocomplete_fields`.
- admin.E040: `<modeladmin>` must define `search_fields`, because it's referenced by `<other_modeladmin>.autocomplete_fields`.

#### `ModelAdmin`

The following checks are performed on any `ModelAdmin` that is registered with the admin site:

- admin.E101： `save_as` 的值必须是个布尔值。
- admin.E102： `save_on_top` 的值必须是个布尔值。
- admin.E103： `inlines` 的值必须是个列表或元组。
- admin.E104： `<InlineModelAdmin class>` 必须继承自 `InlineModelAdmin`。
- admin.E105： `<InlineModelAdmin class>` 必须有个 `model` 属性。
- admin.E106： `<InlineModelAdmin class>.model` 的值必须是个 `Model`。
- admin.E107： `list_display` 的值必须是个列表或元组。
- admin.E108: The value of `list_display[n]` refers to `<label>`, which is not a callable, an attribute of `<ModelAdmin class>`, or an attribute or method on `<model>`.
- admin.E109： `list_display[n]` 的值绝对不能是个 `ManyToManyField` 字段。
- admin.E110: The value of `list_display_links` must be a list, a tuple, or `None`.
- admin.E111: The value of `list_display_links[n]` refers to `<label>`, which is not defined in `list_display`.
- admin.E112: The value of `list_filter` must be a list or tuple.
- admin.E113: The value of `list_filter[n]` must inherit from `ListFilter`.
- admin.E114: The value of `list_filter[n]` must not inherit from `FieldListFilter`.
- admin.E115: The value of `list_filter[n][1]` must inherit from `FieldListFilter`.
- admin.E116: The value of `list_filter[n]` refers to `<label>`, which does not refer to a Field.
- admin.E117: The value of `list_select_related` must be a boolean, tuple or list.
- admin.E118: The value of `list_per_page` must be an integer.
- admin.E119: The value of `list_max_show_all` must be an integer.
- admin.E120: The value of `list_editable` must be a list or tuple.
- admin.E121: The value of `list_editable[n]` refers to `<label>`, which is not an attribute of `<model>`.
- admin.E122: The value of `list_editable[n]` refers to `<label>`, which is not contained in `list_display`.
- admin.E123: The value of `list_editable[n]` cannot be in both `list_editable` and `list_display_links`.
- admin.E124: The value of `list_editable[n]` refers to the first field in `list_display` (`<label>`), which cannot be used unless `list_display_links` is set.
- admin.E125: The value of `list_editable[n]` refers to `<field name>`, which is not editable through the admin.
- admin.E126: The value of `search_fields` must be a list or tuple.
- admin.E127: The value of `date_hierarchy` refers to `<field name>`, which does not refer to a Field.
- admin.E128: The value of `date_hierarchy` must be a `DateField` or `DateTimeField`.
- admin.E129: `<modeladmin>` must define a `has_<foo>_permission()` method for the `<action>` action.
- admin.E130: `__name__` attributes of actions defined in `<modeladmin>` must be unique.

#### `InlineModelAdmin`

The following checks are performed on any `InlineModelAdmin` that is registered as an inline on a `ModelAdmin`.

- admin.E201: Cannot exclude the field `<field name>`, because it is the foreign key to the parent model `<app_label>.<model>`.
- admin.E202: `<model>` has no `ForeignKey` to `<parent model>`./ `<model>` has more than one `ForeignKey` to `<parent model>`.
- admin.E203: The value of `extra` must be an integer.
- admin.E204: The value of `max_num` must be an integer.
- admin.E205: The value of `min_num` must be an integer.
- admin.E206: The value of `formset` must inherit from `BaseModelFormSet`.

#### `GenericInlineModelAdmin`

The following checks are performed on any `GenericInlineModelAdmin` that is registered as an inline on a `ModelAdmin`.

- admin.E301: `'ct_field'` references `<label>`, which is not a field on `<model>`.
- admin.E302: `'ct_fk_field'` references `<label>`, which is not a field on `<model>`.
- admin.E303: `<model>` has no `GenericForeignKey`.
- admin.E304: `<model>` has no `GenericForeignKey` using content type field `<field name>` and object ID field `<field name>`.

#### `AdminSite`

The following checks are performed on the default `AdminSite`:

- admin.E401: `django.contrib.contenttypes` must be in `INSTALLED_APPS` in order to use the admin application.
- admin.E402: `django.contrib.auth.context_processors.auth` must be enabled in `DjangoTemplates` (`TEMPLATES`) if using the default auth backend in order to use the admin application.
- admin.E403: A `django.template.backends.django.DjangoTemplates` instance must be configured in `TEMPLATES` in order to use the admin application.
- admin.E404: `django.contrib.messages.context_processors.messages` must be enabled in `DjangoTemplates` (`TEMPLATES`) in order to use the admin application.
- admin.E405: `django.contrib.auth` must be in `INSTALLED_APPS` in order to use the admin application.
- admin.E406: `django.contrib.messages` must be in `INSTALLED_APPS` in order to use the admin application.
- admin.E408: `django.contrib.auth.middleware.AuthenticationMiddleware` must be in `MIDDLEWARE` in order to use the admin application.
- admin.E409: `django.contrib.messages.middleware.MessageMiddleware` must be in `MIDDLEWARE` in order to use the admin application.
- admin.E410: `django.contrib.sessions.middleware.SessionMiddleware` must be in `MIDDLEWARE` in order to use the admin application.

### `auth`

- auth.E001: `REQUIRED_FIELDS` must be a list or tuple.
- auth.E002: The field named as the `USERNAME_FIELD` for a custom user model must not be included in `REQUIRED_FIELDS`.
- auth.E003: `<field>` must be unique because it is named as the `USERNAME_FIELD`.
- auth.W004: `<field>` is named as the `USERNAME_FIELD`, but it is not unique.
- auth.E005: The permission codenamed `<codename>` clashes with a builtin permission for model `<model>`.
- auth.E006: The permission codenamed `<codename>` is duplicated for model `<model>`.
- auth.E007: The `verbose_name` of model `<model>` must be at most 244 characters for its builtin permission names to be at most 255 characters.
- auth.E008: The permission named `<name>` of model `<model>` is longer than 255 characters.
- auth.C009: `<User model>.is_anonymous` must be an attribute or property rather than a method. Ignoring this is a security issue as anonymous users will be treated as authenticated!
- auth.C010: `<User model>.is_authenticated` must be an attribute or property rather than a method. Ignoring this is a security issue as anonymous users will be treated as authenticated!

### `contenttypes`

The following checks are performed when a model contains a `GenericForeignKey` or `GenericRelation`:

- contenttypes.E001: The `GenericForeignKey` object ID references the nonexistent field `<field>`.
- contenttypes.E002: The `GenericForeignKey` content type references the nonexistent field `<field>`.
- contenttypes.E003: `<field>` is not a `ForeignKey`.
- contenttypes.E004: `<field>` is not a `ForeignKey` to `contenttypes.ContentType`.
- contenttypes.E005: Model names must be at most 100 characters.

### `postgres`

The following checks are performed on `django.contrib.postgres` model fields:

- postgres.E001: Base field for array has errors: ...
- postgres.E002: Base field for array cannot be a related field.
- postgres.E003: `<field>` default should be a callable instead of an instance so that it's not shared between all field instances.

### `sites`

The following checks are performed on any model using a `CurrentSiteManager`:

- sites.E001: `CurrentSiteManager` could not find a field named `<field name>`.
- sites.E002: `CurrentSiteManager` cannot use `<field>` as it is not a foreign key or a many-to-many field.

### `staticfiles`

The following checks verify that `django.contrib.staticfiles` is correctly configured:

- staticfiles.E001: The `STATICFILES_DIRS` setting is not a tuple or list.
- staticfiles.E002: The `STATICFILES_DIRS` setting should not contain the `STATIC_ROOT` setting.
- staticfiles.E003: The prefix `<prefix>` in the `STATICFILES_DIRS` setting must not end with a slash.