ImportError: No module named flask.ext.wtf

from flask.ext.wtf import Form, TextField, BooleanField
from flask.ext.wtf import Required

然而，这时候会报错：ImportError: No module named flask.ext.wtf
是因为在flask0.9.0 之后，Flask-WTF will not import anything from wtforms, you need to import fields from wtforms.
所以你要这样：

from flask.ext.wtf import Form

from wtforms import TextField, BooleanField
from wtforms.validators import Required