Extending pyserde

pyserde offers three ways to extend pyserde to support non builtin types.

Custom field (de)serializer

See custom field serializer.

💡 Tip: wrapping serde.field with your own field function makes

import serde

def field(*args, **kwargs):
    serde.field(*args, **kwargs, serializer=str)

@serde
class Foo:
    a: int = field(default=0)  # Configuring field serializer

Custom class (de)serializer

See custom class serializer.

Custom global (de)serializer

You apply the custom (de)serialization for entire codebase by registering class (de)serializer by add_serializer and add_deserializer. Registered class (de)serializers are stacked in pyserde's global space and automatically used for all the pyserde classes.

e.g. Implementing custom (de)serialization for datetime.timedelta using isodate package.

Here is the code of registering class (de)serializer for datetime.timedelta. This package is actually published in PyPI as pyserde-timedelta.

from datetime import timedelta
from plum import dispatch
from typing import Type, Any
import isodate
import serde

class Serializer:
    @dispatch
    def serialize(self, value: timedelta) -> Any:
        return isodate.duration_isoformat(value)

class Deserializer:
    @dispatch
    def deserialize(self, cls: Type[timedelta], value: Any) -> timedelta:
        return isodate.parse_duration(value)

def init() -> None:
    serde.add_serializer(Serializer())
    serde.add_deserializer(Deserializer())

Users of this package can reuse custom (de)serialization functionality for datetime.timedelta just by calling serde_timedelta.init().

import serde_timedelta
from serde import serde
from serde.json import to_json, from_json
from datetime import timedelta

serde_timedelta.init()

@serde
class Foo:
    a: timedelta

f = Foo(timedelta(hours=10))
json = to_json(f)
print(json)
print(from_json(Foo, json))

and you get datetime.timedelta to be serialized in ISO 8601 duration format!

{"a":"PT10H"}
Foo(a=datetime.timedelta(seconds=36000))

💡 Tip: You can register as many class (de)serializer as you want. This means you can use as many pyserde extensions as you want. Registered (de)serializers are stacked in the memory. A (de)serializer can be overridden by another (de)serializer.

e.g. If you register 3 custom serializers in this order, the first serializer will completely overridden by the 3rd one. 2nd one works because it is implemented for a different type.

1. Register Serializer for int
2. Register Serializer for float
3. Register Serializer for int

New in v0.13.0.