DatastoreODM

Async ODM for Google Cloud Datastore (Firebase in Datastore mode)

Created to ease usage of the official client by structuring data with Django-like constructor

How to use

from orm import Kind

# Create scheme
class Book(Kind):
    class AuthorField(EmbeddedBaseField):
        id = IntegerField()
        name = StringField()

    title = StringField(index=True)
    language = StringField(valid=lambda value: True if value == "en" or value == "ja" else False, default="other")
    released = BooleanField(index=True, default=False)

    author = AuthorField(default=AuthorField)
    co_authors = ListField(AuthorField)

    n_borrowed = IntegerField(default=0)


# Create entity
new_book = Book("No Longer Human", "ja", released=True)
# If not specified, Id will be allocated and assigned during the instance creation
print(new_book.id)
new_book.author.name = "Osamu Dazai"

# Upsert entity (Create / Update)
await new_book.save()

# Find record by id
book = await Book.find(new_book.id)
print(book.title)

# Query database
released_books = Book.find_where(released=True, language="ja", _quantity=3)
async for book in released_books:
    print(book.title)

# Delete record
await new_book.delete()

# Find a record by id or create one with given id and values if it wasn't found
book = await Book.find_or_create(new_book.id, **new_book.entity)
print(book.title)

Supported field types

Regular IntegerField FloatField BooleanField StringField DatatimeField. Custom types can be created by inheriting BaseField

Iterable ListField DictField. Custom types can be created by inheriting ComplexBaseField

Special EmbeddedField

Field arguments

• index If a field should be indexed
  Type bool. Default False
• default Default value for a field
  Type Any (Callable will be executed to retrieve a value). Default None
• valid Function to validate a value
  Type Callable[[Any], bool]. Default lambda _: True

Features

Transaction decorator

Comfortable way of performing atomic mutations

@db.transaction(retry=True, retry_timeout=1)
async def cleanup(*args, batch, **kwargs) -> Any:
    # perform mutations
    return # something

Pessimistic lock

Seamless pessimistic lock on reading (while using the ODM)

class Book(Kind):
    _p_lock = True # To activate
    ...

Custom Kind name

By default, the Kind is retrieved from class name of an instance, but you can specify your own name

class Book(Kind):
    _kind = "notabook"
    ...

Inheritance

Kind and EmbeddedBaseField support both liniar and multiple inheritance

class Book(Kind):
    title = StringField()


class LockedBook(Book):
    _kind = "book"
    _p_lock = True