XSD Attributes

All attributes are declared as simple types.

What is an Attribute?

Simple elements cannot have attributes. If an element has attributes, it is considered to be of a complex type. But the attribute itself is always declared as a simple type.

How to Define an Attribute?

The syntax for defining an attribute is:

<xs:attribute name="xxx" type="yyy"/>

XML Schema has a lot of built-in data types. The most common types are:

• xs:string
• xs:decimal
• xs:integer
• xs:boolean
• xs:date
• xs:time

Example

Here is an XML element with an attribute:

<lastname lang="EN">Smith</lastname>

And here is the corresponding attribute definition:

<xs:attribute name="lang" type="xs:string"/>

Default and Fixed Values for Attributes

Attributes may have a default value OR a fixed value specified.

A default value is automatically assigned to the attribute when no other value is specified.

In the following example the default value is "EN":

<xs:attribute name="lang" type="xs:string" default="EN"/>

A fixed value is also automatically assigned to the attribute, and you cannot specify another value.

In the following example the fixed value is "EN":

<xs:attribute name="lang" type="xs:string" fixed="EN"/>

Optional and Required Attributes

Attributes are optional by default. To specify that the attribute is required, use the "use" attribute:

<xs:attribute name="lang" type="xs:string" use="required"/>

Restrictions on Content

When an XML element or attribute has a data type defined, it puts restrictions on the element's or attribute's content.

If an XML element is of type "xs:date" and contains a string like "Hello World", the element will not validate.

With XML Schemas, you can also add your own restrictions to your XML elements and attributes. These restrictions are called facets. You can read more about facets in the next chapter.

Ektron CMS400.NET Version 7.6 delivers all of the flexibility and features you need to deploy the Web site you want, quickly and efficiently. learn more...       6 ways to take your site to the next level with Ektron: Create site stickiness through social networking. Keep it personal, relevant and interactive and they'll come back for more. Keep it open. Your site needs to be ready and able to connect to outside services. Ektron's open API gives you maximum flexibility. Streamline content and document management. Users need to quickly and intuitively find and add information. Empower your content authors. Reduce IT bottlenecks by allowing business users to create and edit Web content and forms. Climb to the top of search rankings. SEO tools, URL aliasing and eCommerce for your digital marketing strategy Add powerful Web 2.0 tools like blogs, wikis, forums, geo-mapping, rating systems and RSS feeds easily. See why there are 20,000+ Ektron integrations worldwide. Request an INSTANT DEMO or download a FREE TRIAL today.