求助,ValueError: View function did not return a response

新手在学 flask 开发 T.T ，看到《 python web 开发》第十章的用户资料， 在搞 管理员级别的资料编辑器 那里出问题了， 视图函数抛出异常，不能返回响应 。百度，谷歌， sof 无果。找好久了没解决，心塞 所以来寻求帮助，谢谢能提供帮助的人。 这是整个文件夹 http://pan.baidu.com/s/1kV4sXcr

ValueError
ValueError: View function did not return a response

Traceback (most recent call last)
File "D:\web_develop\venv\lib\site-packages\flask-0.12-py2.7.egg\flask\app.py", line 1994, in __call__
return self.wsgi_app(environ, start_response)
File "D:\web_develop\venv\lib\site-packages\flask-0.12-py2.7.egg\flask\app.py", line 1985, in wsgi_app
response = self.handle_exception(e)
File "D:\web_develop\venv\lib\site-packages\flask-0.12-py2.7.egg\flask\app.py", line 1540, in handle_exception
reraise(exc_type, exc_value, tb)
File "D:\web_develop\venv\lib\site-packages\flask-0.12-py2.7.egg\flask\app.py", line 1982, in wsgi_app
response = self.full_dispatch_request()
File "D:\web_develop\venv\lib\site-packages\flask-0.12-py2.7.egg\flask\app.py", line 1615, in full_dispatch_request
return self.finalize_request(rv)
File "D:\web_develop\venv\lib\site-packages\flask-0.12-py2.7.egg\flask\app.py", line 1630, in finalize_request
response = self.make_response(rv)
File "D:\web_develop\venv\lib\site-packages\flask-0.12-py2.7.egg\flask\app.py", line 1725, in make_response
raise ValueError('View function did not return a response')
ValueError: View function did not return a response

##路由视图 views.py ：

@main.route('/edit-profile/<int:id>', methods=['GET', 'POST'])
@login_required
@admin_required
def edit_profile_admin(id):
	user = User.query.get_or_404(id)
	form = EditProfileAdminForm(user=user)
	if form.validate_on_submit():
		user.email = form.email.data
		user.username = form.username.data
		user.confirmed = form.confirmed.data
		user.role = Role.query.get(form.role.data)
		user.name = form.name.data
		user.location = form.location.data
		user.about_me = form.about_me.data
		db.session.add(user)
		flash('The profile has been updated.')
		return redirect(url_for('.user', username=user.username))
	form.email.data = user.email
	form.username.data = user.username
	form.confirmed.data = user.confirmed
	form.role.data = user.role_id
	form.name.data = user.name
	form.location.data = user.location
	form.about_me.data = user.about_me
	return render_template('edit_profile.html', form=form, user=user)

##表单 forms.py:

class EditProfileAdminForm(FlaskForm):
	email = StringField('Email', validators=[Required(), Length(1, 64),
		Email()])
	username = StringField('Username', validators=[
		Required(), Length(1, 64), Regexp('^[A-Za-z][A-Za-z0-9_.]*$', 0,
										  'Username must have only letters,'
										   'number, dots or underscores')])
	confirmed = BooleanField('Confirmed')
	role = SelectField('Role', coerce=int)
	name = StringField('Real name', validators=[Length(0, 64)])
	location = StringField('Location', validators=[Length(0, 64)])
	about_me = TextAreaField('About me')
	submit = SubmitField('Submit')
	
	def __init__(self, user, *args, **kwargs):
		super(EditProfileAdminForm, self).__init__(*args, **kwargs)
		self.role.choices = [(role.id, role.name)
							 for role in Role.query.order_by(Role.name).all()]
		self.user = user
		
	def validate_email(self, field):
		if field.data != self.user.email and \
				User.query.filter_by(email=field.date).first():
			raise ValidationError('Emai already registered.')
	
	def validate_username(self, field):
		if field.data !=self.user.username and \
				User.query.filter_by(username=field.data).first():
			raise ValidationError('Username already in use.')

##模板 edit_profile.html ：

{% extends "base.html" %}
{% import "bootstrap/wtf.html" as wtf %}

{% block title %}Flasky - Edit Profile{% endblock %}

{% block page_content %}
<div class="page-header">
	<h1>Edit Your Profile</h1>
</div>
<div class="col-md-4">
	{{ wtf.quick_form(form) }}
</div>
{% endblock %}