IBM BPM, V8.0.1, All platforms > Programming IBM BPM > Business objects programming > Programming techniques > Use the Sequence object to set data order

How do I work with a model group array?

A model group array is created when a model group has a value for maxOccurs > 1.

Since model groups are flattened and not expressed in a DataObject, the properties inside of the model group become multiple cardinality properties so that their isMany() methods return true if they are not already true. Their minOccurs and maxOccurs facets become multiplied by that of the containing model group. Choice will multiply the maxOccurs facet in the same way as the other model groups, but will always use 0 as the multiplication value for minOccurs because any data in a choice may not be selected.

For example, the following XSD has a model group array:

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
		targetNamespace="http://ModelGroupArray">
  <xsd:complexType name="ModelGroupArray">
    <xsd:sequence minOccurs="2" maxOccurs="5">
      <xsd:element name="element1" type="xsd:string"/>
      <xsd:element name="element2" type="xsd:string" 
			minOccurs="0" maxOccurs="3"/>
	</xsd:sequence>
  </xsd:complexType>
</xsd:schema>

As stated, element1 and element2 will now be multiple cardinality so that a get(...) accessor would return a List. Element1 has a default minOccurs of 1 and a default maxOccurs of 1. Element2 has a minOccurs of 0 and a maxOccurs of 3. In the following example, their new minOccurs and maxOccurs will be as follows:

DataObject - ModelGroupArray
	Property[0] - element1 - minOccurs=(2*1)=2 - maxOccurs=(5*1)=5
	Property[1] - element2 - minOccurs=(2*0)=0 - maxOccurs=(5*3)=15

If the type were Choice:

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
		targetNamespace="http://ModelGroupArray">
  <xsd:complexType name="ModelGroupArray">
    <xsd:choice minOccurs="2" maxOccurs="5">
      <xsd:element name="element1" type="xsd:string"/>
      <xsd:element name="element2" type="xsd:string" 
			minOccurs="0" maxOccurs="3"/>
	</xsd:sequence>
  </xsd:complexType>
</xsd:schema>

Would generate the following minOccurs due to the exclusion of choice that only element1 can be picked each time or only element2 could be picked each time, so to pass validation both need to be able to have 0 occurrences:

DataObject - ModelGroupArray
	Property[0] - element1 - minOccurs=(0*1)=0 - maxOccurs=(5*1)=5
	Property[1] - element2 - minOccurs=(0*0)=0 - maxOccurs=(5*3)=15

Use the Sequence object to set data order

Related concepts:
Model group support (all, choice, sequence, and group references)