error
Raises a custom error
Description
The fn:error function allows you to stop execution of the query, with a specific error message. This is useful if an unexpected or invalid condition exists, such as a missing or invalid data item. You can incorporate calls to the fn:error function in your query to signal such problems to the query user.
It is implementation-dependent how a processor will use the optional $description and $error-object arguments. Most processors will report the $description as part of the error message to the user.
Some processors may report the error name as a URI, where the local part is a fragment identifier, as in http://datypic.com/err#ProdNumReq.
The fn:error function is the same function that the processor calls implicitly whenever there is an error during query evaluation. The return type of none is only used for the fn:error function and is not available to query authors. It simply means that the fn:error function never returns any value; evaluation of the query stops once the fn:error function is called.
Parameters |
Description |
|---|---|
error:string() |
a qualified name for the error |
description:string() |
a description of the error |
error-object:item() |
the item(s) that raised the error |
Examples
XPath |
Results |
Explanation |
|---|---|---|
error() |
Error |
|
error(xs:QName(‘dty:ProdNumReq’)) |
Error |
Assumes the dty prefix has been declared. |
error(QName(’http://datypic.com/err’, ‘ProdNumReq’), ‘Missing number.’) |
Error |
|
error(QName(’http://datypic.com/err’, ‘ProdNumReq’), ‘Missing number.’, $prod) |
Error |