Running Django in docker

I am trying to learn Django (a python framework for developing web) in docker container recently. After running the docker with port redirect

The output of Django server is

Then I use command sudo docker ps to find out the port number for host machine:

but when using curl 127.0.0.1:49198 in host machine it just report “Connection Refused”

After searching in google, I only find one article which seems useful for me. But my problem is still there after I follow its steps for solution. With no choice, I have to read the documents of docker carefully and do my experiment step by step.
First, I run a nc-server in docker:

Then using nc 127.0.0.1 8000 in host. It failed too. Why can’t nc client connect to server in docker even I followed the document of docker?After running netstat in docker, I find out the answer: my centos image is centos7 and the ‘nc’ in it will listen on ipv6 address by default. If anyone want to listen on ipv4 address, it should type in

Now, the nc client could connect to server now.
But how to run Django server in ipv4 address? This article tells me the way. Now, it seems everything is ok. I start Django again with python manage.py runserver 127.0.0.1:8000 but it still could not be connected with nc client in host. Oh, the ip “127.0.0.1” and “0.0.0.0” is very different so I should run Django like:

The browser in host could access the Django example site now.