Add registration form, view, template

app/auth/forms.py

@@ -14,7 +14,25 @@ class LoginForm(FlaskForm):
 
 
 class RegistrationForm(FlaskForm):
-    email = StringField('Email', validators=[DataRequired(), Length(1, 64), Email()])
+    email = StringField('Email', validators=[DataRequired(), Length(1, 64),
+                                             Email()])
+    username = StringField('Username', validators=[
+        DataRequired(), Length(1, 64),
+        Regexp('^[A-Za-z][A-Za-z0-9_.]*$', 0,
+               'Usernames must have only letters, numbers, dots or '
+               'underscores')])
+    password = PasswordField('Password', validators=[
+        DataRequired(), EqualTo('password2', message='Passwords must match.')])
+    password2 = PasswordField('Confirm password', validators=[DataRequired()])
+    submit = SubmitField('Register')
+
+    def validate_email(self, field):
+        if User.query.filter_by(email=field.data.lower()).first():
+            raise ValidationError('Email already registered.')
+
+    def validate_username(self, field):
+        if User.query.filter_by(username=field.data).first():
+            raise ValidationError('Username already in use.')
 
 
 class PasswordResetRequestForm(FlaskForm):