Question

我试图用Django做一些练习并编写一个简单的博客应用程序。我想使用脚本创建我的模型，所以我不必使用shell或管理界面。

给出以下代码：

def populate():
    current_user = User.objects.get(username='testuser')
    blogger_data = {'user': current_user,'bio':"this is my test bio", 'likes': 5,}
    blogger = add_blogger(blogger_data)

    print("Registered blogger : %s" %blogger.user)
    for num in range(5):
        post_data = {'author':current_user, 'title':"test title %s"%num, 'description': "test description%s"%num, 'content': "test content%s"%num,}
        posted_date = datetime.datetime.today() + datetime.timedelta(days=1)
        post = add_post(post_data,num,posted_date)
        comment_data = {'author':current_user, 'post':post,'content':"test content %s"%num, 'upvotes':num, 'downvotes':5-num,}
        comment = add_comment(comment_data)
        response_data = {'author':current_user, 'comment':comment, 'content':"test response %s"%num, 'upvotes':5-num, 'downvotes':num,}
        response = add_response(response_data)
        print("Saved post : %s, comment: %s, response: %s..." %(post,comment,response))
    print("Script succesfully saved data!")

def add_post(data_dict,views, posted_date):
    post = Post.objects.get_or_create(author=data_dict['author'])[0]
    post.title = data_dict['title']
    post.description = data_dict['description']
    post.content =  data_dict['content']
    post.views = views
    post.posted_date = posted_date
    post.save()
    return post

def add_comment(data_dict):
    c = Comment.objects.get_or_create(author=data_dict['author'],post=data_dict['post'])[0]
    c.content = data_dict['content']
    c.upvotes = data_dict['upvotes']
    c.downvotes = data_dict['downvotes']
    c.save()
    return c

def add_response(data_dict):
    r = Response.objects.get_or_create(author=data_dict['author'],comment=data_dict['comment'])[0]
    r.content = data_dict['content']
    r.upvotes = data_dict['upvotes']
    r.downvotes = data_dict['downvotes']
    r.save()
    return r

def add_blogger(data_dict):
    blogger = Blogger.objects.get_or_create(user=data_dict['user'])[0]
    blogger.bio = data_dict['bio']
    blogger.likes = data_dict['likes']
    blogger.save()
    return blogger

if __name__=='__main__':
    print("Starting Blog population script...")
populate()

型号：

class Post(models.Model):
    author = models.ForeignKey(User)
    title = models.CharField(max_length=64, help_text="The post's title.", unique=True)
    description = models.CharField(max_length=128, help_text="A short description of the post.")
    content = models.CharField(max_length=8192, help_text="Your post content.")
    views = models.IntegerField(default=0)
    slug = models.SlugField(blank=True)
    created_date = models.DateField(default=timezone.now)
    posted_date = models.DateField(blank=True,null=True)


    def __str__(self):
        return self.title

    def save(self, *args, **kwargs):
        self.slug = slugify(self.title)
        if not self.posted_date:
            self.posted_date = datetime.today()
        super(Post, self).save(*args, **kwargs)

class Comment(models.Model):
    author = models.ForeignKey(User)
    post = models.ForeignKey(Post)
    content = models.CharField(max_length=1024)
    upvotes = models.IntegerField(default=0)
    downvotes = models.IntegerField(default=0)

    def __str__(self):
        return "%s (%s)(%s)"%(self.content[:20]+"...",self.post,self.author)

class Response(models.Model):
    author = models.OneToOneField(User,primary_key=True)
    comment= models.ForeignKey(Comment, models.SET_NULL, blank=True, null=True)
    content = models.CharField(max_length=1024, help_text="Your message in response to a desired comment.")
    upvotes = models.IntegerField(default=0)
    downvotes = models.IntegerField(default=0)

    def __str__(self):
        return "%s (%s)(%s)" % (self.content[:20]+"...",self.author,self.content)

class Blogger(models.Model):
    user = models.OneToOneField(User, primary_key=True)
    bio = models.CharField(max_length=1024, help_text="A short bio that viewers can see about you.")
    profilepic = models.ImageField(upload_to='profilepics')
    likes = models.IntegerField(default=0)
    joined_date = models.DateField(default=datetime.today)

    def __str__(self):
        return user.username

    def save(self, *args, **kwargs):
        self.joined_date = timezone.now()
        super(Blogger, self).save(*args, **kwargs)

运行脚本后，只有在循环的最后一次迭代中创建的模型实例才会保存在数据库中。究竟发生了什么？

Answer 1

您只有一个用户，您可以在每次迭代中使用它。这意味着您对Post的get_or_create调用将在第一次迭代中为该用户创建帖子，但在每次后续迭代中都将获取现有实例并更新它。随后对其余函数的调用将执行与它们依次传递Post和Comment相同的操作。

使用填充脚本保存Django多个模型实例仅保存在上一次迭代中创建的实例

1 个答案: