# marshmallow-generic
**Generic schema with full typing support and minimal boilerplate**
---
**Documentation**: daniil-berg.github.io/marshmallow-generic
**Source Code**: github.com/daniil-berg/marshmallow-generic
---
Extension for **`marshmallow`** to make deserialization to objects easier and improve type safety.
The main `GenericSchema` class extends `marshmallow.Schema` making it **generic** in terms of the class that data should be deserialized to, when calling `load`/`loads`.
With `GenericSchema` there is no need to explicitly write `post_load` hooks to initialize the object anymore. 🎉
If the "model" class is (for example) `User`, it just needs to be passed as the type argument, when subclassing `GenericSchema`. The output of the `load`/`loads` method will then be automatically inferred as either `User` or `list[User]` (depending on whether `many` is `True` or not) by any competent type checker. ✨
## Usage Example
```python
from marshmallow_generic import GenericSchema, fields
class User:
def __init__(self, name: str, email: str) -> None:
self.name = name
self.email = email
def __repr__(self) -> str:
return "".format(self=self)
...
class UserSchema(GenericSchema[User]):
name = fields.Str()
email = fields.Email()
user_data = {"name": "Monty", "email": "monty@python.org"}
schema = UserSchema()
single_user = schema.load(user_data)
print(single_user) #
json_data = '''[
{"name": "Monty", "email": "monty@python.org"},
{"name": "Ronnie", "email": "ronnie@stones.com"}
]'''
multiple_users = schema.loads(json_data, many=True)
print(multiple_users) # [, ]
```
Adding `reveal_type(single_user)` and `reveal_type(multiple_users)` at the bottom and running that code through `mypy` would yield the following output:
```
# note: Revealed type is "User"
# note: Revealed type is "builtins.list[User]"
```
With the regular `marshmallow.Schema`, the output of `mypy` would instead be this:
```
# note: Revealed type is "Any"
# note: Revealed type is "Any"
```
This also means your IDE will be able to infer the types and thus provide useful auto-suggestions for the loaded objects. 👨💻
Here is PyCharm with the example from above:
## Installation
`pip install marshmallow-generic`
## Dependencies
Python Version `3.9+` and `marshmallow` (duh)