title: Custom Serializers sidebar_position: 4 id: python_custom_serializers license: | Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

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Implement custom serialization logic for specialized types.

Implementing Custom Serializers

Override write/read for Python mode, xwrite/xread for cross-language:

import pyfory
from pyfory.serializer import Serializer
from dataclasses import dataclass

@dataclass
class Foo:
    f1: int
    f2: str

class FooSerializer(Serializer):
    def __init__(self, fory, cls):
        super().__init__(fory, cls)

    def write(self, buffer, obj: Foo):
        # Custom serialization logic
        buffer.write_varint32(obj.f1)
        buffer.write_string(obj.f2)

    def read(self, buffer):
        # Custom deserialization logic
        f1 = buffer.read_varint32()
        f2 = buffer.read_string()
        return Foo(f1, f2)

    # For cross-language mode
    def xwrite(self, buffer, obj: Foo):
        buffer.write_int32(obj.f1)
        buffer.write_string(obj.f2)

    def xread(self, buffer):
        return Foo(buffer.read_int32(), buffer.read_string())

f = pyfory.Fory()
f.register(Foo, type_id=100, serializer=FooSerializer(f, Foo))

# Now Foo uses your custom serializer
data = f.dumps(Foo(42, "hello"))
result = f.loads(data)
print(result)  # Foo(f1=42, f2='hello')

Buffer API

Write Methods

# Integers
buffer.write_int8(value)
buffer.write_int16(value)
buffer.write_int32(value)
buffer.write_int64(value)

# Variable-length integers
buffer.write_varint32(value)
buffer.write_varint64(value)

# Floating point
buffer.write_float32(value)
buffer.write_float64(value)

# Strings and bytes
buffer.write_string(value)
buffer.write_bytes(value)

# Boolean
buffer.write_bool(value)

Read Methods

# Integers
value = buffer.read_int8()
value = buffer.read_int16()
value = buffer.read_int32()
value = buffer.read_int64()

# Variable-length integers
value = buffer.read_varint32()
value = buffer.read_varint64()

# Floating point
value = buffer.read_float32()
value = buffer.read_float64()

# Strings and bytes
value = buffer.read_string()
value = buffer.read_bytes(length)

# Boolean
value = buffer.read_bool()

When to Use Custom Serializers

  • External types from other packages
  • Types with special serialization requirements
  • Legacy data format compatibility
  • Performance-critical custom encoding
  • Types that don't work well with automatic serialization

Registering Custom Serializers

fory = pyfory.Fory()

# Register with type_id
fory.register(MyClass, type_id=100, serializer=MySerializer(fory, MyClass))

# Register with typename (for xlang)
fory.register(MyClass, typename="com.example.MyClass", serializer=MySerializer(fory, MyClass))

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