Hello,
while trying to test for the mere existence of a datamodel node it turned
out, that Data() yields to different results depending on the availability
of an immediate textual content of the node:
1) Example, path does not match, Data() is expected to return null:
<log label="NULL" expr="Data(data,'objectList/obje...@status = 1]') == null"
/>
WARNING: Data(): No nodes matching the XPath expression "objectList/obje...@status
= 1]", returning null
INFO: NULL: false
-> expected: true
2) Example, same as 1) but tested with empty(), apparently an empty string is
returned:
<log label="NULL" expr="empty(Data(data,'objectList/obje...@status = 1]'))" />
WARNING: Data(): No nodes matching the XPath expression "objectList/obje...@status
= 1]", returning null
INFO: NULL: true
3) Example, testing a container with no immediate textual content:
<log label="EMPTY" expr="empty(Data(data,'objectList/object'))" />
WARNING: Data(): Multiple nodes matching XPath expression
"objectList/object", returning first
INFO: EMPTY: true
4) Example, testing a leaf element with immediate textual content:
<log label="EMPTY" expr="empty(Data(data,'objectList/object/status'))" />
WARNING: Data(): Multiple nodes matching XPath expression
"objectList/object/status", returning first
INFO: EMPTY: false
The method apparently invoked in this context: Object
org.apache.commons.scxml.Builtin#data()
calls SCXMLHelper#getNodeValue() to retrieve a textual representation of the
node. This is done
at the level of immediate child nodes, which themselves are not processed
recursively. According
to 1) and 3) there seems to be no test to distiguish whether a node is
missing at all or it has
element only content. For the former I'd expect null as return value, for the
latter all text nodes
concatenated in a deep frist traversal of all child nodes ?
Thank you
Jaro
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