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Serializing and deserializing unions with xsi:type

In XSD, a union is a way to merge the lexical spaces of several simple datatypes known as members.

The following example XSD shows a union that has the members of an integer and a date.

<xsd:simpleType name="integerOrDate">
	<xsd:union memberTypes="xsd:integer xsd:date"/>
</xsd:simpleType>

This multiple typing can cause confusion during deserialization and when manipulating the data.

Business objects support SDO's using xsi:type for serialization and will follow the same algorithm for determining the type on a deserialization if the xsi:type is not present in the XML data.

So to guarantee that the data (the number "42" in this example) would be deserialized as an integer, you can use the xsi:type specified in the input XML. You can also order the member list of the union in the XSD so that the integer comes before the string. The following example shows how both methods are implemented:

<integerOrString xsi:type="xsd:integer">42</integerOrString>

<xsd:simpleType name="integerOrString">
	<xsd:union memberTypes="xsd:integer xsd:string"/>
</xsd:simpleType>

Likewise, if the user wanted the data to be deserialized as a string, then either of the following changes would cause that behavior:

<integerOrString xsi:type="xsd:string">42</integerOrString>

<xsd:simpleType name="integerOrString">
	<xsd:union memberTypes="xsd:string xsd:integer"/>
</xsd:simpleType>

If that if a string type is the first member of the union, it never has any information loss. It can also hold any data that will always be chosen by the no xsi:type algorithm. If you want to use a type other than string, you must either use xsi:type in the XML or reorder the member types in the XSD to give the other members a chance to accept the data.

Resolving property names that contain periods