Valley

Python extensible schema validations and declarative syntax helpers.

Installation

pip install valley

Getting Started

class Animal(Schema):
    name = CharProperty(required=True)
    species = CharProperty(required=True)
    color = CharProperty(required=True)
    meal_type = CharProperty()
    age = IntegerProperty(required=True)
    
frog = Animal(name='Kermit',species='frog',color='green',meal='carnivore',age=1)
frog.validate()

Python Versions

Python 3.6+

• Projects using Valley
• Schema and Declarative Syntax Helpers
• Properties
• JSON Encoders and Decoder

Projects Using Valley

• kev - K.E.V. (Keys, Extra Stuff, and Values) is a Python ORM for key-value stores. Currently supported backends are Redis, S3, DynamoDB, and a S3/Redis hybrid backend.
• formy - Formy is a Python forms library with Jinja2 templates

Schema and Declarative Syntax Helpers

The schema class (valley.contrib.Schema) provides the model for validating properties. Valley also includes utilities (valley.declarative) to make building declarative syntax validation libraries easier. See an example below.

from six import with_metaclass

from valley.declarative import DeclaredVars as DV, \
    DeclarativeVariablesMetaclass as DVM
from valley.schema import BaseSchema
from valley.properties import *


class DeclaredVars(DV):
    base_field_class = BaseProperty
    base_field_type = '_base_properties'


class DeclarativeVariablesMetaclass(DVM):
    declared_vars_class = DeclaredVars


class Schema(with_metaclass(DeclarativeVariablesMetaclass, BaseSchema)):
    _create_error_dict = False
    BUILTIN_DOC_ATTRS = []
    
#If you just want to build upon an existing schema use valley.contrib.Schema

class Animal(Schema):
    name = CharProperty(required=True)
    species = CharProperty(required=True)
    color = CharProperty(required=True)
    meal_type = CharProperty()
    age = IntegerProperty(required=True)

>>bear = Animal(name="Yogi",species="bear",color="brown",meal_type="carnivore",age=5)
>>bear.is_valid
False
>>bear.validate()
>>bear.is_valid
True
>>frog = Animal(name="Kermit",species="frog",color="green",meal_type="carnivore")
>>frog.is_valid
False
>>frog.validate()

ValidationException                       Traceback (most recent call last)

      1 frog = Animal(name='Frog',color='Green',meal_type='carnivore')
      2 
      3 frog.validate()

/home/coder/workspace/valley/valley/schema.pyc in validate(self)
     55                     self._errors[key] = e.error_msg
     56                 else:
     57                     raise e
     58             value = prop.get_python_value(data.get(key))
     59             data[key] = value

ValidationException: age: This value is required

Properties

BaseProperty

Base class that all of the following properties are subclassed from.

Default Validators

• RequiredValidator (if the required kwarg is set)

CharProperty

Validates that the input is a string type.

Example

from valley.properties import CharProperty

first_name = CharProperty(required=True,min_length=1,max_length=20)
first_name.validate('Some string','First Name')

Default Validators

• Validators from BaseProperty
• StringValidator
• MinLengthValidator (if min_length kwarg is set)
• MaxLengthValidator (if max_length kwarg is set)

SlugProperty

Validates that the input is a string type but is also a slug (ex. this-is-a-slug).

Example

from valley.properties import SlugProperty

slug = SlugProperty(required=True,min_length=1,max_length=20)
slug.validate('some-slug','Slug')

Default Validators

• Validators from BaseProperty
• StringValidator
• MinLengthValidator (if min_length kwarg is set)
• MaxLengthValidator (if max_length kwarg is set)
• SlugValidator

EmailProperty

Validates that the input is a string type but is also in valid email format.

Example

from valley.properties import EmailProperty

email = EmailProperty(required=True,min_length=1,max_length=20)
email.validate('[email protected]','Email')

Default Validators

• Validators from BaseProperty
• StringValidator
• MinLengthValidator (if min_length kwarg is set)
• MaxLengthValidator (if max_length kwarg is set)
• EmailValidator

IntegerProperty

Validates that the input is a integer type.

Example

from valley.properties import IntegerProperty

age = IntegerProperty(required=True,min_value=1,max_value=20)
age.validate(5,'Age')

Default Validators

• Validators from BaseProperty
• IntegerValidator
• MinValuehValidator (if min_value kwarg is set)
• MaxLengthValidator (if max_value kwarg is set)

FloatProperty

Validates that the input is a float type.

Example

from valley.properties import FloatProperty

gpa = FloatProperty(required=True,min_value=1,max_value=20)
gpa.validate(4.0,'GPA')

Default Validators

• Validators from BaseProperty
• FloatValidator
• MinValuehValidator (if min_value kwarg is set)
• MaxLengthValidator (if max_value kwarg is set)

BooleanProperty

Validataes that the input is a bool type.

Example

from valley.properties import BooleanProperty

active = BooleanProperty()
active.validate(True,'Active')

Default Validators

• Validators from BaseProperty
• BooleanValidator

DateProperty

Validates that the input is a date object or a string that can be transformed to a date object.

Example

from valley.properties import DateProperty

active = DateProperty(required=True)
active.validate('2017-03-27','Active')

Default Validators

• Validators from BaseProperty
• DateValidator

DateTimeProperty

Validates that the input is a datetime object or a string that can be transformed to a datetime object.

Example

from valley.properties import DateTimeProperty

active = DateTimeProperty(required=True)
active.validate('2017-03-03 12:00:00','Active')

Default Validators

• Validators from BaseProperty
• DateTimeValidator

DictProperty

Validates that the input is a dict object.

Example

from valley.properties import DictProperty

person = DictProperty(required=True)
person.validate({'first':'Eddie','last':'Murphy'},'First Name')

Default Validators

• Validators from BaseProperty
• DictValidator

ListProperty

Validates that the input is a list object.

Example

from valley.properties import ListProperty

schools = ListProperty(required=True)
schools.validate(['Jones School','Edwards School'],'Schools')

Default Validators

• Validators from BaseProperty
• ListValidator

ForeignProperty

Validates that the input is an instance of another class

Example

from valley.properties import ForeignProperty

district = ForeignProperty(District,required=True)
district.validate(District(name='Durham'),'District')

Default Validators

• Validators from BaseProperty
• ForeignValidator

ForeignListProperty

Validates that the input is an instance of another class

Example

from valley.properties import ForeignListProperty

great_schools = ForeignListProperty(School,required=True)
great_schools.validate([School(name='Duke'),School(name='Hampton University')],'Great Schools')
#Go Duke
terrible_schools = ForeignListProperty(School,required=True)
terrible_schools.validate([School(name='UNC'),School(name='Howard')],'Terrible Schools')

Default Validators

• Validators from BaseProperty
• ListValidator
• ForeignListValidator

JSON Encoders and Decoder

ValleyEncoder

Paired with the json.dumps it parses through Schema objects and returns valid json.

Example

import json
from valley.utils.json_utils import ValleyEncoder
from valley.contrib import Schema
from valley.properties import *

class NameSchema(Schema):
    _create_error_dict = True
    name = CharProperty(required=True)

    def __unicode__(self):
        return self.name


class Breed(NameSchema):
    pass


class Dog(NameSchema):
    breed = ForeignProperty(Breed,required=True)


class Troop(NameSchema):
    dogs = ForeignListProperty(Dog)
    primary_breed = ForeignProperty(Breed)


>>> cocker = Breed(name='Cocker Spaniel')

>>> cockapoo = Breed(name='Cockapoo')

>>> bruno = Dog(name='Bruno',breed=cocker)

>>> blitz = Dog(name='Blitz',breed=cockapoo)

>>> durham = Troop(name='Durham',dogs=[bruno,blitz],primary_breed=cocker)

>>> print(json.dumps(durham, cls=ValleyEncoder))
{
  "dogs": [
    {
      "breed": {
        "name": "Cocker Spaniel",
        "_type": "valley.tests.examples.schemas.Breed"
      },
      "name": "Bruno",
      "_type": "valley.tests.examples.schemas.Dog"
    },
    {
      "breed": {
        "name": "Cockapoo",
        "_type": "valley.tests.examples.schemas.Breed"
      },
      "name": "Blitz",
      "_type": "valley.tests.examples.schemas.Dog"
    }
  ],
  "primary_breed": {
    "name": "Cocker Spaniel",
    "_type": "valley.tests.examples.schemas.Breed"
  },
  "name": "Durham",
  "_type": "valley.tests.examples.schemas.Troop"
}

ValleyEncoderNoType

Same as ValleyEncoder except it doesn't add _type attributes.

Example

import json
from valley.utils.json_utils import ValleyEncoderNoType
from valley.contrib import Schema
from valley.properties import *

class NameSchema(Schema):
    _create_error_dict = True
    name = CharProperty(required=True)

    def __unicode__(self):
        return self.name


class Breed(NameSchema):
    pass


class Dog(NameSchema):
    breed = ForeignProperty(Breed,required=True)


class Troop(NameSchema):
    dogs = ForeignListProperty(Dog)
    primary_breed = ForeignProperty(Breed)


>>> cocker = Breed(name='Cocker Spaniel')

>>> cockapoo = Breed(name='Cockapoo')

>>> bruno = Dog(name='Bruno',breed=cocker)

>>> blitz = Dog(name='Blitz',breed=cockapoo)

>>> durham = Troop(name='Durham',dogs=[bruno,blitz],primary_breed=cocker)

>>> print(json.dumps(durham, cls=ValleyEncoderNoType))
{
  "dogs": [
    {
      "breed": {
        "name": "Cocker Spaniel"
      },
      "name": "Bruno"
    },
    {
      "breed": {
        "name": "Cockapoo"
      },
      "name": "Blitz"
    }
  ],
  "primary_breed": {
    "name": "Cocker Spaniel"
  },
  "name": "Durham"
}

ValleyDecoder

Paired with the json.loads it create Schema objects from json

Example

import json

from valley.utils.json_utils import ValleyDecoder

json_string = '{
  "dogs": [
    {
      "breed": {
        "name": "Cocker Spaniel",
        "_type": "valley.tests.examples.schemas.Breed"
      },
      "name": "Bruno",
      "_type": "valley.tests.examples.schemas.Dog"
    },
    {
      "breed": {
        "name": "Cockapoo",
        "_type": "valley.tests.examples.schemas.Breed"
      },
      "name": "Blitz",
      "_type": "valley.tests.examples.schemas.Dog"
    }
  ],
  "primary_breed": {
    "name": "Cocker Spaniel",
    "_type": "valley.tests.examples.schemas.Breed"
  },
  "name": "Durham",
  "_type": "valley.tests.examples.schemas.Troop"
}'

>>> durham = json.loads(json_string,cls=ValleyDecoder)
<Troop: Durham >
>>> durham.name
'Durham
>>> durham.primary_breed.name
Cocker Spaniel