validators.py

Go to the documentation of this file.

#!/usr/bin/python
# -*- coding: utf-8 -*- 
#
# This file contains validator objects designed to be called as 
# functions in order to validate values. They are useful for 
# simple and quick validation schemes where you don't need
# advanced handling.
#
# To use them, simply create an instance of a class and then call it 
# as in 
#
# validator = RangeValidator(0, 100)
# validator(200)
#
# The validator will throw an exception if the value is not correct.
 
import dateutil.parser
 
# *********************************************************************
class BaseValidator(object):
  """Base class that doesn't do anything yet, but is a convenient
  place to add any functionality that is common to all validators.
  """
  pass
 
# *********************************************************************
class FakeValidator(BaseValidator):
  """Automatically passes all values.
  """
  
  def __call__(self, fieldname, value): 
    pass
 
# *********************************************************************
class NullValidator(BaseValidator):
  """Throws an exception on NULL values.
  """
  def __call__(self, fieldname, value): 
    if value == None:
      raise Exception(f'{fieldname} cannot be null!')
    
# *********************************************************************
class BlankValidator(BaseValidator):
  """Throws an exception on blank values.
  """
  def __call__(self, fieldname, value): 
    if not value:
      raise Exception(f'{fieldname} cannot be blank!')
    
# *********************************************************************
class EmailValidator(BaseValidator):
  """Throws an exception on invalid email addresses.
  
  Note that this is a simple regex, so it won't validate more advanced
  email addresses.
  """
  def __call__(self, fieldname, value): 
    if not re.match(r"/[a-z0-9!#%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9] (?:[a-z0-9-]*[a-z0-9])?/i", value):
      raise Exception(f'{value} is not a valid email address!')
 
# *********************************************************************
class DateValidator(BaseValidator):
  """Throws an exception on invalid date strings.
  
  Note that this simpy uses dateutil's parse(), so it won't 
  validate more advanced dates.
  """
  def __call__(self, fieldname, value): 
    try:
      dateutil.parser.parse(value)
    except:
      raise Exception(f'{value} is not a valid date!')
      
# *********************************************************************
class TimeValidator(BaseValidator):
  """Throws an exception on invalid time strings.
  
  Note that this simpy uses dateutil's parse(), so it won't 
  validate more advanced dates.
  """
  def __call__(self, fieldname, value): 
    try:
      dateutil.parser.parse(value)
    except:
      raise Exception(f'{value} is not a valid time!')
      
# *********************************************************************
class DateTimeValidator(BaseValidator):
  """Throws an exception on invalid datetime strings.
  
  Note that this simpy uses dateutil's parse(), so it won't 
  validate more advanced dates.
  """
  def __call__(self, fieldname, value): 
    try:
      dateutil.parser.parse(value)
    except:
      raise Exception(f'{value} is not a valid date!')
 
# *********************************************************************
class RangeValidator(BaseValidator):
  """Throws an exception if the value is too high or too low.
  """
  
  # -------------------------------------------------------------------
  def __init__(self, min, max):
    self.min  = min
    self.max  = max
    
  # -------------------------------------------------------------------
  def __call__(self, fieldname, value): 
    if value < self.min:
      raise Exception(f'{value} is too low for {fieldname}!')
      
    if value > self.max:
      raise Exception(f'{value} is too high for {fieldname}!')