Flask Babel doesn't work
I find where I was wrong. The translations folder is in the wrong place. It should under iInvest(which is app in other cases)..
pybabel extract -F babel.cfg -k lazy_gettext -o messages.pot iInvest/pybabel init -i messages.pot -d iInvest/translations -l zh_Hans_CNpybabel compile -f -d iInvest/translations