Django将模型外键默认值应用于现有记录

Question

Thank you very much for taking your time.

Previously, I posted this question, How to Get Unread Posts for Users .

The problem was: I cannot filter out which article one user has not read while this article has already been read by another user.

I figured out why I cannot do that---- because I have data that I wrote into the database without using Django although I set the reading default for each post to False---- there is simply no record.

Then, I manually set one article to unread to a user in the Admin, everything works, because now in the database there is one record stating that this certain article has not been read by this user.

The problem now is:

How do I set "unread" for every existing article that I have in the database for all existing users?

And how can articles stay unread for every new user unless the new user actually read it?

For your convenience, I copied the codes to here.

My model:

class Posts(models.Model):
 title = models.CharField(max_length=255)
 content_url = models.URLField(unique=True)
 content = models.CharField(max_length=255)
 post_date = models.DateField(default="2999-12-12")

Another

class readstatus(models.Model):
 reading_status = models.BooleanField(default=False)
 user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
 article = models.ForeignKey(Posts, on_delete=models.CASCADE)
 created = models.DateTimeField(auto_now_add=True)

My View:

class DailyReading(ListView):

 template_name = 'reading.html'
 context_object_name = "data" 
 paginate_by = 20
 def get_queryset(self):

    if self.kwargs['status'] == "read":
        queryset = piaoyou.objects.filter(readstatus__reading_status=True,readstatus__user=self.request.user)
        return queryset
    else:
        queryset= Posts.objects.filter(readstatus__reading_status=False,readstatus__user=self.request.user)
        return queryset

My Template:

    {% for info in data %}
                <quoteblock>
                    <ul>
                        <li><a href="{{ info.get_absolute_url }}">{{ info.title }}
                            <footnote></footnote>
                        </a>{{ info.post_date }}</li>

                        <footnote>{{ info.get_abstract_content }}</footnote>
                    </ul>
                </quoteblock>

       {% endfor %}

Answer 1

OMG, I just figured out how to do this.

For an article that has been read by the requesting user, we can just pass queryset = Post.objects.filter(readstatus__reading_status=True, readstatus__user=self.request.user)

For an article that has not been read by the requesting user yet, we can pass Posts.objects.all() into the template.

Then in the template:

We need {% if instance.readstatus_set.all %} this line to make things work. Assume there is no data about whether this requesting user has read the article, the instance should not have readstatus_set.all, which means the user has not read the article yet. Once checking this if condition, we can carry out to check other conditions in the loop.