Real World XML

Creating Choices

A choice lets you specify a number of elements, only one of which will be chosen. To create a choice in XML schemas, you use the <xsd:choice> element. The code that follows is an example. In this case, I'll change the transactionType type so that the borrower can borrow either several books or just one book. I do this by creating an <xsd:choice> element that holds both a <books> element and a <book> element. Note that, in this case, the <book> element needs to be made into a global element so I can refer to it in this choice. Thus, I remove it from the declaration of the <books> element, as you see here:

 xsd:complexType name="transactionType"> <xsd:sequence> <xsd:element name="Lender" type="address"/> <xsd:element name="Borrower" ...