XSLT, 2nd Edition

The generate-id() Function

Before we leave the topic of linking, we’ll go over the details of the generate-id() function. This function takes a node-set as its argument, and it works as follows:

• For a given transformation, every time generate-id() is invoked against a given node, it returns the same ID. The ID doesn’t change while you’re doing a given transformation. If you run the transformation again tomorrow, there’s no guarantee that generate-id() will generate the same ID that it generated today. As long as the XSLT processor is running, however, generate-id() returns the same ID for the same node every time.

• If you invoke generate-id() against two different nodes, the two generated IDs will be different.

• [1.0] Given a node-set, generate-id() returns an ID for the node in the node-set that occurs first in document order.

  [2.0] It is a fatal error in XSLT 2.0 to pass a sequence of more than one item to generate-id().

• If the node-set you pass to the function is empty (you invoke generate-id(fleeber), and there are no <fleeber> elements in the current context), generate-id() returns an empty string.

• If no node-set is passed in (you invoke generate-id()), the function generates an ID for the context node.

Note

The generate-id() function is not required to check whether an ID it generates duplicates an ID that’s already in the document. In other words, if your document has an attribute of type ID with a value of sdk3829a, there’s a possibility that an ID returned by generate-id() will also ...