Skip to main content

Base class for data objects

Project description

Description:

Simple base class for creating data object (it means objects, dedicated to storing data only). It’s a little bit similar to case class from Scala. Using it as base class, You don’t need to take care of data objects boilerplate (like __str__, __eq__, __hash__ methods). Main features: * Objects are considered to be equal based on public fields (method with names started with _ are not took into account) values instead of object identity * __str__ and __repr__ methods return values based on public fields * Static method for creating instances from dictionary. Main difference to dict unpacking is that all non matching keys are ignored and default values are supported * there are two base classes: DataObject and ImmutableDataObject. The second on creates immutable object (so value assigned once to field, cannot be changed)

WARNING: > In future version default behavior may change. It’s still under consideration, whether two different classes with the same set of fields and values should be equal

Install

pip install data_object

Usage

DataObject

from data_object import DataObject


class CustomClass(DataObject):
    def __init__(self, foo, bar):
        self.foo = foo
        self.bar = bar

Str and Repr:

a = CustomClass('a', 'b')
print(a) # output: {"bar": "b", "foo": "a"}
print(repr(a)) # output: CustomClass(bar=b, foo=a)

Equality and Hash

class OtherClass(DataObject):
    def __init__(self, foo, bar):
        self.foo = foo
        self.bar = bar

a = CustomClass('a', 'b')
b = CustomClass('a', 'b')
c = CustomClass('a', 'z')
d = OtherClass('a', 'b')

a == b # True
a == c # False
a == d # True

z = set()
z.add(a)
z.add(b)
z.add(c)
z.add(d)
print(z) # output: {CustomClass(bar=b, foo=a), CustomClass(bar=z, foo=a)}

Creating instances from dict

class SomeClass(DataObject):
    def __init__(self, a, b, c='xyz'):
        self.a = a
        self.b = b
        self.c = c

params1 = {'a': 'aaa', 'b': 'bbb', 'c': 'ccc'}
params2 = {'a': 'xxx', 'b': 'yyy'}
params3 = {'a': 'xxx'}

inst1 = SomeClass.from_dict(params1)
inst2 = SomeClass.from_dict(params2)
inst3 = SomeClass.from_dict(params3, none_if_not_found=True)

print(inst1) # output: {"a": "aaa", "b": "bbb", "c": "ccc"}
print(inst2) # output: {"a": "xxx", "b": "yyy", "c": "xyz"}
print(inst3) # output: {"a": "xxx", "b": null, "c": "xyz"}

ImmutableDataObject

from data_object import ImmutableDataObject

class CustomImmutableClass(ImmutableDataObject):
    def __init__(self, foo, bar):
        self.foo = foo
        self.bar = bar

inst = CustomImmutableClass('abc', 'xyz')
print(inst) # output: {"bar": "xyz", "foo": "abc"}

inst.foo = 'aaa'

will produce exception:

Traceback (most recent call last):
...
data_object.exceptions.ImmutableObjectViolation: Changing attributes not permitted for immutable object

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distributions

No source distribution files available for this release.See tutorial on generating distribution archives.

Built Distribution

data_object-1.2.0-py3-none-any.whl (9.1 kB view hashes)

Uploaded Python 3

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page