wtform

gistfile1.py

from flask.ext.wtf import (Form, TextField, PasswordField, Required,
                           Email, BooleanField, EqualTo)
from prism.models.user import User
from sqlalchemy import or_


class RegistrationForm(Form):
    username = TextField('Username',
                         validators=[Required()])
    password = PasswordField('Password', validators=[Required()])
    password_confirm = PasswordField(
        'Password confirmation',
        validators=[Required(),
                    EqualTo('password', message="Passwords don't match")])
    email = TextField('E-mail', validators=[Required(), Email()])

    def validate(self):
        is_valid = Form.validate(self)

        errors = {}

        # Validate fields are not already taken.
        unique_fields = ('username', 'email')
        message = '%s already taken.'

        clauses = {field: getattr(User, field) == getattr(self, field).data
                   for field in unique_fields if field not in self.errors}

        if clauses:
            users = User.query.filter(or_(*clauses.values())).all()
            errors = {field: message % getattr(self, field).label.text
                      for user in users for field in clauses.keys()
                      if getattr(user, field) == getattr(self, field).data}

        self.errors.update(errors)
        return is_valid and not errors

splited.py

from flask.ext.wtf import (Form, TextField, PasswordField, Required,
                           Email, BooleanField, EqualTo)
from prism.models.user import User
from sqlalchemy import or_


class RegistrationForm(Form):
    username = TextField('Username',
                         validators=[Required()])
    password = PasswordField('Password', validators=[Required()])
    password_confirm = PasswordField(
        'Password confirmation',
        validators=[Required(),
                    EqualTo('password', message="Passwords don't match")])
    email = TextField('E-mail', validators=[Required(), Email()])

    def validate(self):
        if not Form.validate(self):
            return False

        users = User.query.filter(User.email==self.email.data |
                                  User.username==self.username.data).all()

        if self.email.data in [u.email for u in users]:
            self.errors['email'] = 'Email already registered.'
        if self.username.data in [u.username for u in users]:
            self.errors['username'] = 'Username already taken.'

        return not self.errors