Generate marshmallow schemas from code annotations and type hinting, converting object structures to serializable native types and back effortlessly.
from marshmallow_autoschema import autoschema, validate_field, Many, One
from marshmallow.validate import Range
@validate_field('word_count', Range(0, 10000))
@autoschema
class Page:
def __init__(self, *,
word_count: int=0) -> None: pass
@autoschema
class Book:
def __init__(self, *,
cover: One[Page],
pages: Many[Page]) -> None: pass
data = {
"cover": {"word_count": 12},
"pages": [
{"word_count": 0},
{"word_count": 12},
{"word_count": 100},
],
}
book = Book.load(data)
assert isinstance(book, Book)
assert isinstance(book.cover, Page)
out = book.dump()
assert data == outFor the decorator to work properly, a few properties are required:
- All properties must be listed as arguments in the constructor.
- Only kwonly arguments are considered, the asterisk is required in the declaration.
- Type annotations are required.
- You can't mix traditionals marshmallow schemas with schemas generated by
autoschema
Additionally:
- Default values can be used and apply as normal normal function default values.
- On a List[] type, =None will default to an empty list.
- The constructor body can be specified and is called after all members have been assigned.
Represent one instance of the type passed singly. This annotation is required for any schema type generated by autoschema.
Represent a List of instance of the type passed. This annotation is required for any schema type generated by autoschema.
@autoschema and @autoschema_camelcase are offered as a convenience for the most common cases. For other cases, schema_metafactory can be used.
Arguments:
- schema_base_class: As a minimum, the base schema class must have a post_load handler to create the model object.
- field_namer: Function to convert the class members into the serialized name.
- extended_field_map: Include additional field type handlers for your definitions.
Copyright (c) 2017- Delve Labs Inc.
This library is distributed under the MIT License. See joined LICENSE file for details.