由于验证器,Django 1.8 makemigrations 每次都会生成重复的迁移

Django 1.8 makemigrations generates a duplicated migration every time due to validators

我有一个模型,其中有一个带有以下验证器的字段:

validators=[
        FileValidator(
            allowed_extensions=ALLOWED_PHOTO_EXT,
            allowed_mimetypes=ALLOWED_PHOTO_MIME_TYPES,
            max_size=ALLOWED_PHOTO_MAX_SIZE,
        )
    ],

这是验证器本身

@deconstructible
class FileValidator(object):
    """
    Validator for files, checking the size, extension and mimetype.
    Initialization parameters:
        allowed_extensions: iterable with allowed file extensions
            ie. ('txt', 'doc')
        allowd_mimetypes: iterable with allowed mimetypes
            ie. ('image/png', )
        min_size: minimum number of bytes allowed
            ie. 100
        max_size: maximum number of bytes allowed
            ie. 24*1024*1024 for 24 MB
    Usage example::
        MyModel(models.Model):
            myfile = FileField(validators=FileValidator(max_size=24*1024*1024), ...)

    See https://gist.github.com/jrosebr1/2140738 (improved)
    """

    extension_message = _("Extension '%(extension)s' not allowed. Allowed extensions are: '%(allowed_extensions)s.'")
    mime_message = _("MIME type '%(mimetype)s' is not valid. Allowed types are: %(allowed_mimetypes)s.")
    min_size_message = _('The current file %(size)s, which is too small. The minumum file size is %(allowed_size)s.')
    max_size_message = _('The current file %(size)s, which is too large. The maximum file size is %(allowed_size)s.')

    def __init__(self, *args, **kwargs):
        self.allowed_extensions = kwargs.pop('allowed_extensions', None)
        self.allowed_mimetypes = kwargs.pop('allowed_mimetypes', None)
        self.min_size = kwargs.pop('min_size', 0)
        self.max_size = kwargs.pop('max_size', DEFAULT_FILE_MAX_SIZE)

    def __call__(self, value):
        """
        Check the extension, content type and file size.
        """

        # Check the extension
        ext = splitext(value.name)[1][1:].lower()
        if self.allowed_extensions and not ext in self.allowed_extensions:
            message = self.extension_message % {
                'extension': ext,
                'allowed_extensions': ', '.join(self.allowed_extensions)
            }

            raise ValidationError(message)

        # Check the content type
        # mimetype = mimetypes.guess_type(value.name)[0] # XXX Alternative guessing way, unsure
        mimetype = magic.from_buffer(value.read(1024), mime=True)
        if self.allowed_mimetypes and not mimetype in self.allowed_mimetypes:
            message = self.mime_message % {
                'mimetype': mimetype,
                'allowed_mimetypes': ', '.join(self.allowed_mimetypes)
            }

            raise ValidationError(message)

        # Check the file size
        filesize = len(value)
        if self.max_size and filesize > self.max_size:
            message = self.max_size_message % {
                'size': filesizeformat(filesize),
                'allowed_size': filesizeformat(self.max_size)
            }

            raise ValidationError(message)

        elif filesize < self.min_size:
            message = self.min_size_message % {
                'size': filesizeformat(filesize),
                'allowed_size': filesizeformat(self.min_size)
            }

            raise ValidationError(message)

每次我运行./manage.py makemigrations app1

0003_auto_20180521_0325.py:
    - Alter field xxx on yyy

它每次都会生成一个新的迁移,它总是做同样的事情(改变字段)

如果我注释掉我的验证器,此行为将停止并且 makemigrations 显示 "no change detected" 消息。

怎么了?我怎样才能避免这种行为?


编辑:根据@benjamin 的回答,这里是完整的代码,包括修复。 (__eq__ 函数)

# -*- coding: utf-8 -*-

import magic

from os.path import splitext
from django.core.exceptions import ValidationError
from django.utils.deconstruct import deconstructible
from django.utils.translation import gettext_lazy as _
from django.template.defaultfilters import filesizeformat

DEFAULT_FILE_MAX_SIZE = 10 * 1024 * 1024  # 10Mo

# Photo, like profile picture
# Only allow web-friendly extensions/mime types, since they'll be displayed on web pages
# TODO Size is huge, should be optimised
ALLOWED_PHOTO_EXT = [
    'jpg',
    'jpeg',
    'png',
]

ALLOWED_PHOTO_MIME_TYPES = [
    'image/jpeg',
    'image/pjpeg',
    'image/png',
    'image/x-png',
]

ALLOWED_PHOTO_MAX_SIZE = 10 * 1024 * 1024  # 10Mo

# Any document
# Allow a wide range of extensions and mime types
# TODO Size is huge, should be optimised
ALLOWED_DOCUMENT_EXT = [
    'jpg',
    'jpeg',
    'png',
    'tif',
    'bmp',
    'pdf',
    'doc',
    'dot',
    'docx',
    'dotx',
    'xls',
    'xlt',
    'xla',
    'xlsx',
    'xltx',
    'pptx',
    'potx',
    'ppsx',
]

ALLOWED_DOCUMENT_MIME_TYPES = [
    'image/jpeg',
    'image/pjpeg',
    'image/png',
    'image/x-png',
    'image/tiff',
    'image/bmp',
    'application/pdf',
    'application/vnd.ms-excel',
    'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
    'application/vnd.ms-powerpoint',
    'application/vnd.openxmlformats-officedocument.presentationml.presentation',
    'application/msword',
    'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
    'application/zip',  # XXX PPTX can be detected as ZIP for some reasons
]

ALLOWED_DOCUMENT_MAX_SIZE = 10 * 1024 * 1024  # 10Mo

# Any document sent to SMoney, which have their own rules and limitations
# Allow a wide range of extensions and mime types
# TODO Size is huge, should be optimised
ALLOWED_DOCUMENT_SMONEY_EXT = [
    'jpg',
    'jpeg',
    'png',
    'tif',
    'bmp',
    'pdf',
]

ALLOWED_DOCUMENT_SMONEY_MIME_TYPES = [
    'image/jpeg',
    'image/pjpeg',
    'image/png',
    'image/x-png',
    'image/tiff',
    'image/bmp',
    'application/pdf',
]

ALLOWED_DOCUMENT_SMONEY_MAX_SIZE = 3 * 1024 * 1024  # 3Mo


@deconstructible
class FileValidator(object):
    """
    Validator for files, checking the size, extension and mimetype.
    Initialization parameters:
        allowed_extensions: iterable with allowed file extensions
            ie. ('txt', 'doc')
        allowd_mimetypes: iterable with allowed mimetypes
            ie. ('image/png', )
        min_size: minimum number of bytes allowed
            ie. 100
        max_size: maximum number of bytes allowed
            ie. 24*1024*1024 for 24 MB
    Usage example::
        MyModel(models.Model):
            myfile = FileField(validators=FileValidator(max_size=24*1024*1024), ...)

    See https://gist.github.com/jrosebr1/2140738 (improved)
    """

    extension_message = _("Extension '%(extension)s' not allowed. Allowed extensions are: '%(allowed_extensions)s.'")
    mime_message = _("MIME type '%(mimetype)s' is not valid. Allowed types are: %(allowed_mimetypes)s.")
    min_size_message = _('The current file %(size)s, which is too small. The minumum file size is %(allowed_size)s.')
    max_size_message = _('The current file %(size)s, which is too large. The maximum file size is %(allowed_size)s.')

    def __init__(self, *args, **kwargs):
        self.allowed_extensions = kwargs.pop('allowed_extensions', None)
        self.allowed_mimetypes = kwargs.pop('allowed_mimetypes', None)
        self.min_size = kwargs.pop('min_size', 0)
        self.max_size = kwargs.pop('max_size', DEFAULT_FILE_MAX_SIZE)

    def __call__(self, value):
        """
        Check the extension, content type and file size.
        """

        # Check the extension
        ext = splitext(value.name)[1][1:].lower()
        if self.allowed_extensions and not ext in self.allowed_extensions:
            message = self.extension_message % {
                'extension': ext,
                'allowed_extensions': ', '.join(self.allowed_extensions)
            }

            raise ValidationError(message)

        # Check the content type
        # mimetype = mimetypes.guess_type(value.name)[0] # XXX Alternative guessing way, unsure
        mimetype = magic.from_buffer(value.read(1024), mime=True)
        if self.allowed_mimetypes and not mimetype in self.allowed_mimetypes:
            message = self.mime_message % {
                'mimetype': mimetype,
                'allowed_mimetypes': ', '.join(self.allowed_mimetypes)
            }

            raise ValidationError(message)

        # Check the file size
        filesize = len(value)
        if self.max_size and filesize > self.max_size:
            message = self.max_size_message % {
                'size': filesizeformat(filesize),
                'allowed_size': filesizeformat(self.max_size)
            }

            raise ValidationError(message)

        elif filesize < self.min_size:
            message = self.min_size_message % {
                'size': filesizeformat(filesize),
                'allowed_size': filesizeformat(self.min_size)
            }

            raise ValidationError(message)

    def __eq__(self, other):
        return (
                isinstance(other, self.__class__) and
                self.allowed_extensions == other.allowed_extensions and
                self.allowed_mimetypes == other.allowed_mimetypes and
                self.min_size == self.min_size and
                self.max_size == self.max_size
        )
/app_name/migrations

删除除__init__.py

之外的所有.py文件
python manage.py makemigrations
python manage.py migrate

如果这不起作用,那么您可以尝试我已经做过的事情

在视图中,我像这样检查图像是否有效

def check_image(request):

    if len(request.FILES) != 0:

        image = request.FILES['image'] # <input type="file" name="image" ....>
        ext = os.path.splitext(image.name)[1]

        if ext in ['.jpg', '.jpeg', '.png', '.gif']:
            # file is image
            x=0
        else:
            # file is not image
            y=0

    return HttpResponseRedirect('/')

我愿意猜测这是因为验证器 class 中缺少 __eq__ 方法。默认比较中的某些内容正在寻找 'not equal' 基于其 __dict__ 以相同方式初始化的两个实例。尝试添加一个明确的:

def __eq__(self, other):
    return (isinstance(other, self.__class__) and 
            self.allowed_extensions == other.allowed_extensions and
            self.allowed_mimetypes == other.allowed_mimetypes and
            self.min_size == self.min_size and
            self.max_size == self.max_size
    )