XML Schema composite elements

XSD composite elements

Composite elements contain additional elements and/or properties.

What are composite elements?

A composite element is an XML element that contains other elements and/or properties.

There are four types of composite elements:

• Empty element
• An element that contains other elements
• Contains only elements of text
• An element that contains elements and text

Note: All of the above elements can contain properties!

An example of a composite element

The composite element, "product", is empty:

Composite elements, "employee", contain only other elements:

Composite XML element, "food", contains only text:

Composite XML elements, "description" contains elements and text:

How do I define composite elements?

Look at this composite XML element, "employee", which contains only other elements:

In XML Schema, we have two ways to define composite elements:

1. By naming this element, you can declare the "employee" element directly, as this is:

If you use the method described above, only "employee" can use the specified composite type. N otice that its child elements, "firstname" and "lastname", are surrounded by indicators. T his means that child elements must appear in the order in which they are declared. You'll learn more about indicators in the XSD Indicators section.

2. The "employee" element can use the type property, which refers to the name of the compound type to be used:

If you use the method described above, several elements can use the same composite type, such as this:

You can also build on an existing composite element and add some elements, like this:

Here's what's going on with the XML Schema composite elements, and in the next section, we'll look at the composite empty elements.