Django：更改可选ImageField的url [英] Django: Changing the url of an optional ImageField

问题描述

通过信号我检查我的模型是否属于一个类别。如果是，我想将可选的ImageField更改为特定的URL。

如何实现？下面的代码不工作，我得到无法设置属性错误，因为它是一个可选字段，它是空白的，因为我保存。

这是我的示例模型

  class Foo（models.Model）：
 category = models.IntegerField（max_length = 1）
 poster = models.ImageField（uPoster，blank = True）
  

和我的帖子保存信号： p>

  def post_poster（instance，** kwargs）：
 if instance.category == 1 #a specific category 
 instance.poster.url = u'/ media / special_image_for_1.png'
 instance.save（）
除了MovieCat.DoesNotExist：
 pass 
  

解决方案

你不说你有什么问题（代码是否有效？），所以有你的代码中有两个问题。首先，你可能不想保存在一个后保存信号（无限循环，任何人？）。 其次，您有缩进问题（如果，则需要缩进）。

您可能想要这样做的方式是使用 Model.clean（） 。

定义一个

  def clean（self） ：
 if instance.category == 1 #a特定类别
 instance.poster.url = u'/ media / special_image_for_1.png'
  

Via signals I check if my model belongs to a category. If it is, I want to change my optional ImageField to a specific url.

How can this be achieved? Code below doesnt work, I get "cannot set attribute" error as it is an optional field and it was blank as I saved it.

Here is my sample model

class Foo(models.Model):
    category = models.IntegerField(max_length=1)
    poster = models.ImageField(u"Poster", blank=True)

and my post save signal:

def post_poster(instance, **kwargs):
        if instance.category == 1 #a specific category
            instance.poster.url = u'/media/special_image_for_1.png'
            instance.save()
    except MovieCat.DoesNotExist:
        pass 

解决方案

You don't say what problem you're having (does that code work?), so there are two problems in your code. Firstly, you probably don't want to be saving in a post-save signal (infinite loop, anyone?). Secondly, you've got an indentation issue (you need to indent after the if).

The way you probably want to do this is with Model.clean().

Define a clean method on your model like this:

def clean(self):
  if instance.category == 1 #a specific category
    instance.poster.url = u'/media/special_image_for_1.png'

这篇关于Django：更改可选ImageField的url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IT屋！