NerdWalletOSS/dynamorm

import datetime

from dynamorm import DynaModel, GlobalIndex, ProjectAll

# In this example we'll use Marshmallow, but you can also use Schematics too!
# You can see that you have to import the schema library yourself, it is not abstracted at all
from marshmallow import fields

# Our objects are defined as DynaModel classes
class Book(DynaModel):
    # Define our DynamoDB properties
    class Table:
        name = 'prod-books'
        hash_key = 'isbn'
        read = 25
        write = 5

    class ByAuthor(GlobalIndex):
        name = 'by-author'
        hash_key = 'author'
        read = 25
        write = 5
        projection = ProjectAll()

    # Define our data schema, each property here will become a property on instances of the Book class
    class Schema:
        isbn = fields.String(validate=validate_isbn)
        title = fields.String()
        author = fields.String()
        publisher = fields.String()

        # NOTE: Marshmallow uses the `missing` keyword during deserialization, which occurs when we save
        # an object to Dynamo and the attr has no value, versus the `default` keyword, which is used when
        # we load a document from Dynamo and the value doesn't exist or is null.
        year = fields.Number(missing=lambda: datetime.datetime.utcnow().year)


# Store new documents directly from dictionaries
Book.put({
    "isbn": "12345678910",
    "title": "Foo",
    "author": "Mr. Bar",
    "publisher": "Publishorama"
})

# Work with the classes as objects.  You can pass attributes from the schema to the constructor
foo = Book(isbn="12345678910", title="Foo", author="Mr. Bar",
           publisher="Publishorama")
foo.save()

# Or assign attributes
foo = Book()
foo.isbn = "12345678910"
foo.title = "Foo"
foo.author = "Mr. Bar"
foo.publisher = "Publishorama"

# In all cases they go through Schema validation, calls to .put or .save can result in ValidationError
foo.save()

# You can then fetch, query and scan your tables.
# Get on the hash key, and/or range key
book = Book.get(isbn="12345678910")

# Update items, with conditions
# Here our condition ensures we don't have a race condition where someone else updates the title first
book.update(title='Corrected Foo', conditions=(title=book.title,))

# Query based on the keys
Book.query(isbn__begins_with="12345")

# Scan based on attributes
Book.scan(author="Mr. Bar")
Book.scan(author__ne="Mr. Bar")

# Query based on indexes
Book.ByAuthor.query(author="Mr. Bar")