inheritance.md

Serialization of Inherited Properties

Support for inherited properties was added in v4.2.

Default Behavior

By default, inherited properties are not included in serialization. Only top-level properties will be picked up by the SchemaReflector, and the Serializer will not write inherited properties as parquet columns as a result.

When serializing an array of objects, you're able to pass in a Schema, which defines the columns that will end up in the serialized parquet files. This argument is optional, and defaults to a Schema reflection of the object type you're serializing.
For example, given a SimpleStructure, the default Schema object would be created like this

public class SimpleStructure
{
   public int Id { get; set; }
   public string Name { get; set; }
}

Schema schema = SchemaReflector.Reflect<SimpleStructure>();

This Schema only contains top-level properties. So, a more complex structure that inherits the Id and Name properties from the SimpleStructure wouldn't include those properties in the serialized parquet by default.

public class ComplexStructure : SimpleStructure
{
  public string Description { get; set; }
}

If we were to serialize an instance of a ComplexStructure with the default Schema, the output would only have the Description property, regardless of Id and Name also being set.

Schema defaultSchema = SchemaReflector.Reflect<ComplexStructure>();

defaultSchema.GetDataFields(); 
// => { PropertyInfo(Name="Description") }

How to Include Inherited Properties

In order to include inherited properties when serializing an object, we simply use a different Schema reflection method.

Schema schemaWithInheritedProperties = SchemaReflector.ReflectWithInheritedProperties<ComplexStructure>();

schemaWithInheritedProperties.GetDataFields(); 
/**
 * => { 
 *     PropertyInfo(Name="Id"),
 *     PropertyInfo(Name="Name"),
 *     PropertyInfo(Name="Description")
 * }
 */