如何过滤多对多关系

Question

我希望得到所有与标签相关的帖子：

#models.py
class Post(models.Model):
    tags = models.ManyToManyField('blogUserPlane.Tag')
    title = models.CharField(max_length=200)


class Tag(models.Model):
    name = models.CharField(max_length=200)


#views.py
def get_list_of_posts_by_tag_order_by_date(request):
    # this works
    list_of_posts = Post.objects.all().filter(tags__in=[1, 2])
    # I want to use tags as name, not as id. Samething like this
    # list_of_posts = Post.objects.all().filter(tags__in=["Tag1", "Tag2"])
    html = ["title=%s<br> tags=%s<br>" % (p.title, p.tags.__dict__) for p in 

list_of_posts]         返回HttpResponse（html）

第二个问题是过滤器返回错误的结果：

Post:
| id | title | 
|  1 | post1 | 
|  2 | post2 |

tags:
| id | post_id | tag_id |
|  1 |    1    |    1   |
|  2 |    1    |    2   |
|  3 |    2    |    2   |

Tag:
| id | name | 
|  1 | Tag1 |
|  2 | Tag2 |

list_of_posts = Post.objects.all（）。filter（tags__in = [1,2]）返回： post1，post1，post2，但应该返回post1，post2