python - 图像字段模型形式的 Django 自定义验证(最大文件大小等)

Question

我有一个模型，它有一个名为“横幅”的图像字段，我正在尝试验证文件大小和尺寸，如果图像太大则提供错误。

这是模型.py:

class Server(models.Model):
    id = models.AutoField("ID", primary_key=True, editable=False)
    servername = models.CharField("Server Name", max_length=20)
    ip = models.CharField("IP Address", max_length=50)
    port = models.CharField("Port", max_length=5, default='25565')
    banner = models.ImageField("Banner", upload_to='banners', max_length=100)
    description = models.TextField("Description", blank=True, max_length=3000)
    rank = models.IntegerField(default=0)
    votes = models.IntegerField(default=0)
    website = models.URLField("Website URL", max_length=200, blank=True)
    user = models.ForeignKey(User)
    motd = models.CharField("MOTD", max_length=150, default='n/a')
    playersonline = models.CharField("Online Players", max_length=7, default='n/a')
    online = models.BooleanField("Online", default=False)
    sponsored = models.BooleanField("Sponsored", default=False)
    lastquery = models.DateTimeField('Last Queried', auto_now=True)
    slugurl = models.SlugField("SlugURL", max_length=50)
    def __unicode__(self):
        return "%s (%s:%s)" % (self.servername, self.ip, self.port)

这是带有自定义验证的 forms.py:

class AddServer(ModelForm):
    class Meta:
        model = Server
        fields = ('servername', 'ip', 'port', 'website', 'description', 'banner')

     # Add some custom validation to our image field
    def clean_image(self):
        image = self.cleaned_data.get('banner', False)
        if image:
            if image._size > 1*1024*1024:
                raise ValidationError("Image file too large ( maximum 1mb )")
            if image._height > 60 or image._width > 468:
                raise ValidationError("Image dimensions too large ( maximum 468x60 pixels )")
            return image
        else:
            raise ValidationError("Couldn't read uploaded image")

根据我的阅读，这应该可行，但无论大小，图像都会上传。

我做错了什么还是有更好的方法来做这件事？

Answer 1

方法名应该是clean_<field name> , 在这种情况下 clean_banner .

为了将来引用，我将放置一段我在最近的项目中使用的代码(名称必须适应 OP 代码):

from PIL import Image
from django.utils.translation import ugettext as _

def clean_photo(self):
    image = self.cleaned_data.get('photo', False)

    if image:
        img = Image.open(image)
        w, h = img.size

        #validate dimensions
        max_width = max_height = 500
        if w > max_width or h > max_height:
            raise forms.ValidationError(
                _('Please use an image that is smaller or equal to '
                  '%s x %s pixels.' % (max_width, max_height)))

        #validate content type
        main, sub = image.content_type.split('/')
        if not (main == 'image' and sub.lower() in ['jpeg', 'pjpeg', 'png', 'jpg']):
            raise forms.ValidationError(_('Please use a JPEG or PNG image.'))

        #validate file size
        if len(image) > (1 * 1024 * 1024):
            raise forms.ValidationError(_('Image file too large ( maximum 1mb )'))
    else:
        raise forms.ValidationError(_("Couldn't read uploaded image"))
    return image