https://github.com/lyang/pynamodb-encoder

PynamoDB Model object encoder/decoder to/from dict.
https://github.com/lyang/pynamodb-encoder

dynamodb encoder-decoder json polymorphic pynamodb python

Last synced: 4 days ago
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PynamoDB Model object encoder/decoder to/from dict.

• Host: GitHub
• URL: https://github.com/lyang/pynamodb-encoder
• Owner: lyang
• License: mit
• Created: 2021-11-27T04:22:45.000Z (about 4 years ago)
• Default Branch: main
• Last Pushed: 2026-01-29T05:21:47.000Z (26 days ago)
• Last Synced: 2026-01-29T07:33:45.760Z (26 days ago)
• Topics: dynamodb, encoder-decoder, json, polymorphic, pynamodb, python
• Language: Python
• Homepage:
• Size: 531 KB
• Stars: 6
• Watchers: 1
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# pynamodb-encoder

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## Introduction

`pynamodb-encoder` provides helper classes that can convert [PynamoDB](https://github.com/pynamodb/PynamoDB) `Model` objects into `JSON` serializable `dict`. It can also decode such `dict` back into those `Model` objects. [Polymorphic](https://pynamodb.readthedocs.io/en/latest/polymorphism.html) models and attributes are also supported.

## Examples

```python

def test_encode_complex_model(encoder: Encoder):

    class Pet(DynamicMapAttribute):

        cls = DiscriminatorAttribute()

        name = UnicodeAttribute()

    class Cat(Pet, discriminator="Cat"):

        pass

    class Dog(Pet, discriminator="Dog"):

        pass

    class Human(Model):

        name = UnicodeAttribute()

        pets = ListAttribute(of=Pet)

    jon = Human(name="Jon", pets=[Cat(name="Garfield", age=43), Dog(name="Odie")])

    assert encoder.encode(jon) == {

        "name": "Jon",

        "pets": [{"cls": "Cat", "name": "Garfield", "age": 43}, {"cls": "Dog", "name": "Odie"}],

    }

def test_decode_complex_model(decoder: Decoder):

    class Pet(DynamicMapAttribute):

        cls = DiscriminatorAttribute()

    class Cat(Pet, discriminator="Cat"):

        name = UnicodeAttribute()

    class Dog(Pet, discriminator="Dog"):

        breed = UnicodeAttribute()

    class Human(Model):

        name = UnicodeAttribute()

        age = NumberAttribute()

        pets = ListAttribute(of=Pet)

    jon = decoder.decode(

        Human,

        {

            "name": "Jon",

            "age": 70,

            "pets": [{"cls": "Cat", "name": "Garfield"}, {"cls": "Dog", "breed": "Terrier"}],

        },

    )

    assert jon.name == "Jon"

    assert jon.age == 70

    assert isinstance(jon.pets, list)

    assert len(jon.pets) == 2

    assert isinstance(jon.pets[0], Cat)

    assert jon.pets[0].name == "Garfield"

    assert isinstance(jon.pets[1], Dog)

    assert jon.pets[1].breed == "Terrier"

```

More examples can be found in [encoder_test.py](tests/encoder_test.py) and [decoder_test.py](tests/decoder_test.py)