Django:缓存函数
Django:缓存函数
提问于 2020-10-08 16:31:39
我创建了以下序列化程序，其中我两次调用函数_calculate_image_dimensions。现在，我尝试了@仙人掌属性，但由于必须传递值width, height，所以无法工作。但是，对于get_width和get_height，它们不会改变。是否有办法确保计算只计算一次？
class IntegrationImageSerializer(serializers.ModelSerializer):
width = serializers.SerializerMethodField()
height = serializers.SerializerMethodField()
class Meta:
model = IntegrationImage
fields = ("image", "width", "height")
def _calculate_image_dimensions(self, width, height) -> int:
MAX_IMAGE_SIZE = 350
aspect_ratio = width / height
if width > height:
width = MAX_IMAGE_SIZE
height = width / aspect_ratio
else:
height = MAX_IMAGE_SIZE
width = height * aspect_ratio
return round(width), round(height)
def get_width(self, obj: IntegrationImage) -> int:
width, height = self._calculate_image_dimensions(
obj.image.width, obj.image.height
)
return width
def get_height(self, obj: IntegrationImage) -> int:
width, height = self._calculate_image_dimensions(
obj.image.width, obj.image.height
)
return height回答 2
Stack Overflow用户
回答已采纳
发布于 2020-10-08 16:54:38
最初，我觉得有点困惑，有一个方法get_width执行一个函数，得到宽度和高度，然后只返回width。
使用dimensions字段稍微改变API结构是否有意义(如果width和height被引用到很多地方，这实际上可能并不有效)？
如果不需要更改对width和height的大量引用，这将只调用_calculate_image_dimensions一次(我认为这就是您要解决的问题？)你就不需要缓存了。
class IntegrationImageSerializer(serializers.ModelSerializer):
dimensions = serializers.SerializerMethodField()
class Meta:
model = IntegrationImage
fields = ("image", "dimensions")
def _calculate_image_dimensions(self, width, height) -> int:
MAX_IMAGE_SIZE = 350
aspect_ratio = width / height
if width > height:
width = MAX_IMAGE_SIZE
height = width / aspect_ratio
else:
height = MAX_IMAGE_SIZE
width = height * aspect_ratio
return round(width), round(height)
def get_dimensions(self, obj: IntegrationImage) -> int:
width, height = self._calculate_image_dimensions(
obj.image.width, obj.image.height
)
return {"width": width, "height": height}Stack Overflow用户
发布于 2020-10-08 16:35:44
使它成为一个免费的函数(类外)，并用lru_cache()装饰它
from functools import lru_cache
@lru_cache(maxsize=None)
def calculate_image_dimensions(width, height) -> int:
MAX_IMAGE_SIZE = 350
aspect_ratio = width / height
if width > height:
width = MAX_IMAGE_SIZE
height = width / aspect_ratio
else:
height = MAX_IMAGE_SIZE
width = height * aspect_ratio
return round(width), round(height)这将缓存工作进程生存期的结果。
(不过，我怀疑有几个比较和分区的函数是应用程序的性能瓶颈。)
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/64266839
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