奇怪的字典分配问题

Question

我有两个模型、相册和图片，还有一个函数album_reorder，它接收图片id列表并相应地改变权重。这很好，但是我正在尝试为函数编写测试，例如：

Class ReposTests(unittest.TestCase):
    def test_album_reorder__fail__not_owned(self):

        # Create a test user, album and pictures.
        user = self.create_test_user()
        # create_default_album() generates an Album along with 6 default Picture records.    
        create_default_album(user)
        album = get_first_album(user.profile)
        pictures = Picture.objects.filter(album=album)

        # Get all picture IDs into a list and record each pictures existing weight.
        picture_ids = []
        picture_weights = {}
        for picture in pictures:
            picture_ids.append(picture.id)
            print "%s:%s:%s" % (album.id, picture.id, picture.weight)
            picture_weights[picture.id] = picture.weight

        # Create another test user, album and pictures.
        user2 = self.create_test_user()
        create_default_album(user2)
        album2 = get_first_album(user2.profile)
        pictures2 = Picture.objects.filter(album=album2)

        # Add a Picture ID from a different user to test the restriction that an album cannot be re-ordered if any pictures do not belong to the specified user.
        picture_ids.append(pictures2[0].id)
        print "%s:%s:%s" % (album2.id, pictures2[0].id, pictures2[0].weight)
        picture_weights[pictures[2].id] = pictures2[0].weight

        # Shuffle all picture IDs
        random = Random()
        while pictures[0].id == picture_ids[0]:
            random.shuffle(picture_ids)

        # Reorder picture IDs according to shuffled ID list, however this should fail due to the ownership check.
        album_reorder(user, picture_ids)
        print picture_ids
        print picture_weights

        # Check each
        for picture_id in picture_ids:
            self.assertEqual(picture_weights[picture_id], Picture.objects.get(id=picture_id).weight)

现在问题似乎出在picture_weightsdict的构造方式上。由于以下两行输出：

# Loop output: (album.id, picture.id, picture.weight)
# 1346:5699:0
# 1346:5700:1
# 1346:5701:2
# 1346:5702:3
# 1346:5703:4
# 1346:5704:5
# 1347:5705:0

print picture_ids
# Outputs: [5700L, 5703L, 5702L, 5699L, 5704L, 5705L, 5701L]

print picture_weights
# Outputs: {5699L: 0L, 5700L: 1L, 5701L: 0L, 5702L: 3L, 5703L: 4L, 5704L: 5L}

请注意，picture_ids是7个元素，正如预期的那样，其中aspicture_weights只有6个元素，并且权重与循环输出的权重不匹配。第二个用户图片5705在picture_weights中丢失，但是其中一个picture_weights被分配了不正确的0L权重。你知道吗

我对dict一点经验都没有，不过，我只是想应用我对PHP关联数组的知识，所以我假设我在这方面的知识有差距。谢谢你的建议！你知道吗

Answer 1

列表和词典在以下几行上出现分歧：

    # Add a Picture ID from a different user to test the restriction that an album cannot be re-ordered if any pictures do not belong to the specified user.
    picture_ids.append(pictures2[0].id)
    print "%s:%s:%s" % (album2.id, pictures2[0].id, pictures2[0].weight)
    picture_weights[pictures[2].id] = pictures2[0].weight

注意您是如何使用pictures[2].id，也就是5701L（这就是为什么特定键在字典中的权重会发生变化）。你的意思可能是：

    picture_weights[pictures2[0].id] = pictures2[0].weight