class TweetSerializer(serializers.ModelSerializer):
user = UserSerializerForTweet(source='cached_user')
comments_count = serializers.SerializerMethodField()
likes_count = serializers.SerializerMethodField()
has_liked = serializers.SerializerMethodField()
photo_urls = serializers.SerializerMethodField()
class Meta:
model = Tweet
fields = (
'id',
'user',
'content',
'created_at',
'comments_count',
'likes_count',
'has_liked',
'photo_urls',
)
def get_likes_count(self, obj):
return RedisHelper.get_count(obj, 'likes_count')
def get_comments_count(self, obj):
return RedisHelper.get_count(obj, 'comments_count')
def get_has_liked(self, obj):
return LikeService.has_liked(self.context['request'].user, obj)
def get_photo_urls(self, obj):
photo_urls = []
for photo in obj.tweetphoto_set.all().order_by('order'):
photo_urls.append(photo.file.url)
return photo_urls
class TweetSerializer(serializers.ModelSerializer):
user = UserSerializerForTweet(source='cached_user')
class Meta:
model = Tweet
fields = ('id', 'user', 'created_at', 'content')
class TweetSerializer(serializers.ModelSerializer):
user = UserSerializerForTweet(source='cached_user')
has_liked = serializers.SerializerMethodField()
comments_count = serializers.SerializerMethodField()
likes_count = serializers.SerializerMethodField()
class Meta:
model = Tweet
fields = (
'id',
'user',
'created_at',
'content',
'comments_count',
'likes_count',
'has_liked',
)
def get_has_liked(self, obj):
return LikeService.has_liked(self.context['request'].user, obj)
def get_likes_count(self, obj):
return RedisHelper.get_count(obj, 'likes_count')
def get_comments_count(self, obj):
return RedisHelper.get_count(obj, 'comments_count')
class CommentSerializer(serializers.ModelSerializer):
user = UserSerializerForTweet()
class Meta:
model = Comment
fields = (
'id',
'tweet_id',
'user',
'content',
'created_at',
'updated_at',
)
class TweetSerializerForDetail(TweetSerializer):
user = UserSerializerForTweet(source='cached_user')
comments = CommentSerializerForTweet(source='comment_set', many=True)
class Meta:
model = Tweet
fields = (
'id',
'user',
'created_at',
'content',
'comments',
'comment_count',
'like_count',
'has_liked',
'photo_urls',
)
class TweetSerializer(serializers.ModelSerializer):
user = UserSerializerForTweet(
source='cached_user') # who creates this tweet
comments_count = serializers.SerializerMethodField()
likes_count = serializers.SerializerMethodField()
has_liked = serializers.SerializerMethodField()
photo_urls = serializers.SerializerMethodField()
class Meta:
model = Tweet
fields = (
'id',
'user',
'created_at',
'content',
'comments_count',
'likes_count',
'has_liked',
'photo_urls',
)
def get_likes_count(self, obj):
# select count(*) -> redis get
# N + 1 queries
# N 如果是 db queries -> 不可以接受
# N 如果是 redis/memcached queries -> 可以接受
return RedisHelper.get_count(obj, 'likes_count')
# return obj.like_set.count()
def get_comments_count(self, obj):
# Django定义的反查机制
return RedisHelper.get_count(obj, 'comments_count')
# return obj.comment_set.count()
def get_has_liked(self, obj):
# current login user can be obtained from self.context['request'].user
return LikeService.has_liked(self.context['request'].user, obj)
def get_photo_urls(self, obj):
photo_urls = []
for photo in obj.tweetphoto_set.all().order_by('order'):
photo_urls.append(photo.file.url)
return photo_urls
class TweetSerializerForDetail(TweetSerializer):
user = UserSerializerForTweet()
# <HOMEWORK> 使用 serialziers.SerializerMethodField 的方式实现 comments
comments = CommentSerializer(source='comment_set', many=True)
likes = LikeSerializer(source='like_set', many=True)
class Meta:
model = Tweet
fields = (
'id',
'user',
'comments',
'created_at',
'content',
'likes',
'comments',
'likes_count',
'comments_count',
'has_liked',
'photo_urls',
)
class TweetSerializer(serializers.ModelSerializer):
user = UserSerializerForTweet()
# If user is not defined, user generated by ModelSerializer will be returned
# as integer. It shows up that serializers(e.g. fields here) can be embedded
# in serializers(ModelSerializer)
comments_count = serializers.SerializerMethodField()
likes_count = serializers.SerializerMethodField()
has_liked = serializers.SerializerMethodField()
photo_urls = serializers.SerializerMethodField()
class Meta:
model = Tweet
fields = (
'id',
'user',
'created_at',
'content',
'comments_count',
'likes_count',
'has_liked',
'photo_urls',
)
def get_likes_count(self, obj):
return obj.like_set.count()
def get_comments_count(self, obj):
return obj.comment_set.count()
def get_has_liked(self, obj):
# current login user has this like
return LikeService.has_liked(self.context['request'].user, obj)
def get_photo_urls(self, obj):
photo_urls = []
for photo in obj.tweetphoto_set.all().order_by('order'):
photo_urls.append(photo.file.url)
return photo_urls