prettyrecord 0.2

Structures like SQLAlchemy's declarative_base or Django's models in your project!

prettyrecord allows you to define your data structures in declarative way, similar to SQLAlchemy’s declarative_base or Django’s models. To achieve the goal, prettyrecord uses Python’s descriptor and metaclass mechanisms.

Usage

• to define new structure, subclass Record or derived class and fill with fields, eg.:

  from prettyrecord import Record
  
  
  class DummyRecord(Record, some_trait=False):
      field1 = Field(required=True, default_value='')
      field2 = Field(default_value=0)
      field3 = ListField(constraint=lambda value: -5 < value < 5)
  
  
  dr = DummyRecord(field1='foo', field3=[-2, 3, 1, 0, 4)
  print(dr.field1)          # shows 'foo'
  print(dr.__some_trait__)  # shows 'False'

• to define new field, subclass Field, RecordField, ListField or derived class, eg.:

  from prettyrecord import Field
  
  
  class Integer(Field):
      def normalize(self, value):
          value = super(Integer, self).normalize(value)
          return int(value)

• to change creation process of your structures, subclass MetaRecord and define new base class for them, eg.:

  from prettyrecord.record import Record, MetaRecord
  
  
  class MetaMyRecord(MetaRecord):
      def __new__(mcs, name, bases, attrs, **kwargs):
          # your code here - remember to call super().__new__
  
      def __init__(cls, name, bases, attrs, **kwargs):
          # your code here - remember to call super().__init__
  
  
  class MyRecord(Record, metaclass=MetaMyRecord):
      pass