yasv — Yet Another Simple Validator

yasv is a simple python library for data validation.

Why yasv?

  • it has simple schema definition syntax similar to django or SQLAlchemy models;
  • Python 2.7, 3.2, 3.3 support;
  • simple and minimalistic, no html form overhead;


Just put the following:

pip install yasv


For example we have a scheme with couple of fields.

from yasv import Schema, Field, is_in, required

class UserSchema(Schema):
    name = Field('Name', required)
    sex = Field('Sex', is_in(['male', 'female']))

Then we create instance of User() and set one parameter ‘name’.

user = User(name='George')

Now we can validate user’s data:

>>> s = UserSchema(user)
>>> s.is_valid()

Here is_valid() returns True because user has required field ‘name’. There isn’t field ‘sex’ but it’s optional.

Let’s try not valid data. For this we pass to our scheme empty User() object without any fields:

>>> s = UserSchema(User())
>>> s.is_valid()
>>> s.get_errors()
['Value is required.']

Now is_valid() returns False. As we can see method get_errors() gets the list with all errors for every fields in the scheme.