Python 参数化Tornado请求处理程序
假设我在python Tornado框架中有一个非常简单的web应用程序,只有一个端点。我感兴趣的是返回一个在启动服务器之前计算的值。从中稍微修改的示例就可以了 handler.pyPython 参数化Tornado请求处理程序,python,web-services,tornado,Python,Web Services,Tornado,假设我在python Tornado框架中有一个非常简单的web应用程序,只有一个端点。我感兴趣的是返回一个在启动服务器之前计算的值。从中稍微修改的示例就可以了 handler.py import tornado.web class MainHandler(tornado.web.RequestHandler): def get(self): self.write('I want to return var `expensive_value`') import to
import tornado.web
class MainHandler(tornado.web.RequestHandler):
def get(self):
self.write('I want to return var `expensive_value`')
import tornado.ioloop
import tornado.web
def make_app():
return tornado.web.Application([
(r"/", MainHandler),
])
if __name__ == "__main__":
# calculate some var here before starting the server
expensive_value = 'value from long_calculation()'
app = make_app()
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
import tornado.web
global_variable = None
def setter(val):
global global_variable
global_variable = val
class MainHandler(tornado.web.RequestHandler):
def get(self):
self.write(global_variable)
import tornado.ioloop
import tornado.web
from handler import MainHandler, setter
def make_app():
return tornado.web.Application([
(r"/", MainHandler),
])
if __name__ == "__main__":
expensive_value = 'value from long_calculation()'
setter(expensive_value)
app = make_app()
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
import tornado.web
class MainHandler(tornado.web.RequestHandler):
def initialize(self, expensive_value):
self.expensive_value = expensive_value
def get(self):
self.write(self.expensive_value)
import tornado.ioloop
import tornado.web
from handler import MainHandler
def make_app(parameter):
return tornado.web.Application([
(r"/", MainHandler, {'expensive_value': parameter}),
])
if __name__ == "__main__":
expensive_value = 'value from long_calculation()'
app = make_app(expensive_value)
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
main.py
import tornado.web
class MainHandler(tornado.web.RequestHandler):
def get(self):
self.write('I want to return var `expensive_value`')
import tornado.ioloop
import tornado.web
def make_app():
return tornado.web.Application([
(r"/", MainHandler),
])
if __name__ == "__main__":
# calculate some var here before starting the server
expensive_value = 'value from long_calculation()'
app = make_app()
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
import tornado.web
global_variable = None
def setter(val):
global global_variable
global_variable = val
class MainHandler(tornado.web.RequestHandler):
def get(self):
self.write(global_variable)
import tornado.ioloop
import tornado.web
from handler import MainHandler, setter
def make_app():
return tornado.web.Application([
(r"/", MainHandler),
])
if __name__ == "__main__":
expensive_value = 'value from long_calculation()'
setter(expensive_value)
app = make_app()
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
import tornado.web
class MainHandler(tornado.web.RequestHandler):
def initialize(self, expensive_value):
self.expensive_value = expensive_value
def get(self):
self.write(self.expensive_value)
import tornado.ioloop
import tornado.web
from handler import MainHandler
def make_app(parameter):
return tornado.web.Application([
(r"/", MainHandler, {'expensive_value': parameter}),
])
if __name__ == "__main__":
expensive_value = 'value from long_calculation()'
app = make_app(expensive_value)
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
当运行python main.py
并向端点发送请求时,它当然只返回一个字符串。但是我想返回昂贵的\u值的实际值
。目前我知道有两种解决方案
1.在处理程序中使用全局变量
handler.py
import tornado.web
class MainHandler(tornado.web.RequestHandler):
def get(self):
self.write('I want to return var `expensive_value`')
import tornado.ioloop
import tornado.web
def make_app():
return tornado.web.Application([
(r"/", MainHandler),
])
if __name__ == "__main__":
# calculate some var here before starting the server
expensive_value = 'value from long_calculation()'
app = make_app()
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
import tornado.web
global_variable = None
def setter(val):
global global_variable
global_variable = val
class MainHandler(tornado.web.RequestHandler):
def get(self):
self.write(global_variable)
import tornado.ioloop
import tornado.web
from handler import MainHandler, setter
def make_app():
return tornado.web.Application([
(r"/", MainHandler),
])
if __name__ == "__main__":
expensive_value = 'value from long_calculation()'
setter(expensive_value)
app = make_app()
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
import tornado.web
class MainHandler(tornado.web.RequestHandler):
def initialize(self, expensive_value):
self.expensive_value = expensive_value
def get(self):
self.write(self.expensive_value)
import tornado.ioloop
import tornado.web
from handler import MainHandler
def make_app(parameter):
return tornado.web.Application([
(r"/", MainHandler, {'expensive_value': parameter}),
])
if __name__ == "__main__":
expensive_value = 'value from long_calculation()'
app = make_app(expensive_value)
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
main.py
import tornado.web
class MainHandler(tornado.web.RequestHandler):
def get(self):
self.write('I want to return var `expensive_value`')
import tornado.ioloop
import tornado.web
def make_app():
return tornado.web.Application([
(r"/", MainHandler),
])
if __name__ == "__main__":
# calculate some var here before starting the server
expensive_value = 'value from long_calculation()'
app = make_app()
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
import tornado.web
global_variable = None
def setter(val):
global global_variable
global_variable = val
class MainHandler(tornado.web.RequestHandler):
def get(self):
self.write(global_variable)
import tornado.ioloop
import tornado.web
from handler import MainHandler, setter
def make_app():
return tornado.web.Application([
(r"/", MainHandler),
])
if __name__ == "__main__":
expensive_value = 'value from long_calculation()'
setter(expensive_value)
app = make_app()
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
import tornado.web
class MainHandler(tornado.web.RequestHandler):
def initialize(self, expensive_value):
self.expensive_value = expensive_value
def get(self):
self.write(self.expensive_value)
import tornado.ioloop
import tornado.web
from handler import MainHandler
def make_app(parameter):
return tornado.web.Application([
(r"/", MainHandler, {'expensive_value': parameter}),
])
if __name__ == "__main__":
expensive_value = 'value from long_calculation()'
app = make_app(expensive_value)
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
拥有一个全局变量并从其他模块设置其值对我来说就像是一个反模式
2.在处理程序中使用initialize方法
handler.py
import tornado.web
class MainHandler(tornado.web.RequestHandler):
def get(self):
self.write('I want to return var `expensive_value`')
import tornado.ioloop
import tornado.web
def make_app():
return tornado.web.Application([
(r"/", MainHandler),
])
if __name__ == "__main__":
# calculate some var here before starting the server
expensive_value = 'value from long_calculation()'
app = make_app()
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
import tornado.web
global_variable = None
def setter(val):
global global_variable
global_variable = val
class MainHandler(tornado.web.RequestHandler):
def get(self):
self.write(global_variable)
import tornado.ioloop
import tornado.web
from handler import MainHandler, setter
def make_app():
return tornado.web.Application([
(r"/", MainHandler),
])
if __name__ == "__main__":
expensive_value = 'value from long_calculation()'
setter(expensive_value)
app = make_app()
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
import tornado.web
class MainHandler(tornado.web.RequestHandler):
def initialize(self, expensive_value):
self.expensive_value = expensive_value
def get(self):
self.write(self.expensive_value)
import tornado.ioloop
import tornado.web
from handler import MainHandler
def make_app(parameter):
return tornado.web.Application([
(r"/", MainHandler, {'expensive_value': parameter}),
])
if __name__ == "__main__":
expensive_value = 'value from long_calculation()'
app = make_app(expensive_value)
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
main.py
import tornado.web
class MainHandler(tornado.web.RequestHandler):
def get(self):
self.write('I want to return var `expensive_value`')
import tornado.ioloop
import tornado.web
def make_app():
return tornado.web.Application([
(r"/", MainHandler),
])
if __name__ == "__main__":
# calculate some var here before starting the server
expensive_value = 'value from long_calculation()'
app = make_app()
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
import tornado.web
global_variable = None
def setter(val):
global global_variable
global_variable = val
class MainHandler(tornado.web.RequestHandler):
def get(self):
self.write(global_variable)
import tornado.ioloop
import tornado.web
from handler import MainHandler, setter
def make_app():
return tornado.web.Application([
(r"/", MainHandler),
])
if __name__ == "__main__":
expensive_value = 'value from long_calculation()'
setter(expensive_value)
app = make_app()
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
import tornado.web
class MainHandler(tornado.web.RequestHandler):
def initialize(self, expensive_value):
self.expensive_value = expensive_value
def get(self):
self.write(self.expensive_value)
import tornado.ioloop
import tornado.web
from handler import MainHandler
def make_app(parameter):
return tornado.web.Application([
(r"/", MainHandler, {'expensive_value': parameter}),
])
if __name__ == "__main__":
expensive_value = 'value from long_calculation()'
app = make_app(expensive_value)
app.listen(8888)
tornado.ioloop.IOLoop.current().start()
这个解决方案更好。但是对每个请求都调用initialize
方法。我意识到这样做的开销相当小,但我认为这可能会误导潜在的代码读者,因为昂贵的\u值
永远不会改变
总结
这两种解决方案都有效。但我不喜欢它们中的任何一个,而且似乎我缺少了一些龙卷风的功能解决这个问题的蟒蛇式方法是什么?
例如,我相信Flask有
app.config
字典,可以在处理程序中访问,这似乎是一个很好的解决方案,因为昂贵的\u值
确实是应用程序的配置。但是我在Tornado中没有发现类似的情况。处理程序可以访问self.application.settings
,这是一个包含传递给应用程序
构造函数的附加参数的字典
因此,您可以直接将昂贵的\u值
传递给应用程序
类,如下所示:
def make_app(parameter):
return tornado.web.Application(
[
(r"/", MainHandler),
],
expensive_value=parameter
)
def initialize(self):
self.expensive_value = self.application.settings.get('expensive_value')
并在如下任何处理程序中访问此值:
def make_app(parameter):
return tornado.web.Application(
[
(r"/", MainHandler),
],
expensive_value=parameter
)
def initialize(self):
self.expensive_value = self.application.settings.get('expensive_value')
这正是我要找的!非常感谢。