class Article(models.Model):
    tags=models.ManyToManyField(Tag,blank=True)  #博客标签
class Tag(models.Model):
    name=models.CharField(max_length=50,blank=True)

{%for tag in tags%}
    <label><input type="checkbox" name="tag_list" value={{tag.name}}> {{tag.name}}</label>
{%endfor%}

tag_list=request.POST.getlist("tag_list")
for each in new_article.tags.all():
    new_article.tags.remove(each)  #清空原先的tag
for tag in tag_list:
    temp=Tag.objects.get(name=tag)
    new_article.tags.add(temp)#相反remove
new_article.save()