The solution to gen.Return(\'hello\') appearing in tornado

The reason for the error

In python, Tornado is a networkframework# based on the event loop ##. It uses coroutines to handle concurrency, gen.Return("hello") is a method for returning values ​​in coroutines. When using Tornado's asynchronous capabilities, use gen.Return() to return a value in a coroutine.

How to solve

In Tornado, use yield and gen.Return() to return values. If you want to return a value in a coroutine, you can use yield and gen.Return() to achieve your goal.

For example:

@gen.coroutine
def my_coroutine():
result = yield some_async_call()
raise gen.Return(result)

Use async

io.run() or tornado.gen.convert_yielded() outside the function to get the return value.

result = await my_coroutine()

If you want to return a value in a coroutine, you should use yield and gen.Return() to achieve your goal.

Usage example

The following is a simple example of using coroutines in Tornado and returning values:

import tornado.ioloop
import tornado.gen

@tornado.gen.coroutine
def my_coroutine():
result = yield some_async_call()
raise tornado.gen.Return(result)

def handle_result(result):
print(result)

if __name__ == "__main__":
result = tornado.ioloop.IOLoop.current().run_sync(my_coroutine)
handle_result(result)

Some_async_call() here is an asynchronous function.

If you want to get the return value outside the function, you can do this:

result = await my_coroutine()

Of course, async/await syntax can also be used, which requires adding the async modifier before the function and using await when calling the function.

async def my_coroutine():
result = await some_async_call()
return result

In the above example, result is the return value, which can be processed in handle_result().

The above is the detailed content of The solution to gen.Return(\'hello\') appearing in tornado. For more information, please follow other related articles on the PHP Chinese website!