Jackrabbit XPath Query: UUID with leading number in path - xpath

Question

I have what I think is an interesting problem executing queries in Jackrabbit when a node in the query path is a UUID that start with a number.
For example, this query work fine as the second node starts with a letter, 'f':
/*/JCP/feeadeaf-1dae-427f-bf4e-842b07965a93/label//*[#sequence]
This query however does not, if the first 'f' is replaced with '2':
/*/JCP/2eeadeaf-1dae-427f-bf4e-842b07965a93/label//*[#sequence]
The exception:
Encountered "-" at line 1, column 26.
Was expecting one of:
<IntegerLiteral> ...
<DecimalLiteral> ...
<DoubleLiteral> ...
<StringLiteral> ...
... rest omitted for brevity ...
for statement: for $v in /*/JCP/2eeadeaf-1dae-427f-bf4e-842b07965a93/label//*[#sequence] return $v
My code in general
def queryString = queryFor path
def queryManager = session.workspace.queryManager
def query = queryManager.createQuery queryString, Query.XPATH // fails here
query.execute().nodes
I'm aware my query, with the leading asterisk, may not be the best, but I'm just starting out with querying in general. Maybe using another language other than XPATH might work.
I tried the advice in this post, adding a save before creating the query, but no luck
Jackrabbit Running Queries against UUID
Thanks in advance for any input!

Answer 1

A solution that worked was to try and properly escape parts of the query path, namely the individual steps used to build up the path into the repository. The exception message was somewhat misleading, at least to me, as in made me think that the hyphens were part of the root cause. The root problem was that the leading number in the node name created an illegal XPATH query as suggested above.
A solution in this case is to encode the individual steps into the path and build the rest of the query. Resulting in the leading number only being escaped:
/*/JCP/_x0032_eeadeaf-1dae-427f-bf4e-842b07965a93//*[#sequence]
Code that represents a list of steps or a path into the Jackrabbit repository:
import org.apache.commons.lang3.StringUtils;
import org.apache.jackrabbit.util.ISO9075;
class Path {
List<String> steps; //...
public String asQuery() {
return steps.size() > 0 ? "/*" + asPathString(encodedSteps()) + "//*" : "//*";
}
private String asPathString(List<String> steps) {
return '/' + StringUtils.join(steps, '/');
}
private List<String> encodedSteps() {
List<String> encodedSteps = new ArrayList<>();
for (String step : steps) {
encodedSteps.add(ISO9075.encode(step));
}
return encodedSteps;
}
}
Some more notes:
If we escape more of the query string as in:
/_x002a_/JCP/_x0032_eeadeaf-1dae-427f-bf4e-842b07965a93//_x002a_[#sequence]
Or the original path encoded as a whole as in:
_x002f_a_x002f_fffe4dcf0-360c-11e4-ad80-14feb59d0ab5_x002f_2cbae0dc-35e2-11e4-b5d6-14feb59d0ab5_x002f_c
The queries do not produce the wanted results.
Thanks to #matthias_h and #LarsH

Answer 2

An XML element name cannot start with a digit. See the XML spec's rules for STag, Name, and NameStartChar. Therefore, the "XPath expression"
/*/JCP/2eeadeaf-1dae-427f-bf4e-842b07965a93/label//*[#sequence]
is illegal, because the name test 2eead... isn't a legal XML name.
As such, you can't just use any old UUID as an XML element name nor as a name test in XPath. However if you put a legal NameStartChar on the front (such as _), you can probably use any UUID.
I'm not clear on whether you think you already have XML data with an element named <2eead...> (and are trying to query that element's descendants); if so, whatever tool produced it is broken, as it emits illegal XML. On the other hand if the <2eead...> is something that you yourself are creating, then presumably you have the option of modifying the element name to be a legal XML name.