I have a background in XML/XSLT, these are the things that came to mind:
'real' XPath: X/Y/Z = A
Mendix XPath: X/X_Y/Y/_Z = A
X/X_X[reversed()]
)$Entity/TextString
)So don't try anything like
//BBB[ position() = floor(last() div 2 + 0.5) or position() = ceiling(last() div 2 + 0.5) ]
For basic retrieve functionality, Mendix XPath fulfills the basic needs. A nice addition to original XPath are system variables and tokens, like [$SomethingWithDate/Date = [%BeginOfCurrentDay%]]
though. :)
Have you reviewed the Mendix reference guide for XPath?
I think the main differentiating factor between the full XPath specification and what you end up writing in Mendix is here in that article:
In the Modeler you do not write complete queries but only the constraints. The entity is implicitly determined by the context. So, instead of //Sales.Customer[Name='Jansen'] you only write [Name='Jansen']
There are some other differences in terms of which date constants are available to you, and also the fact that you can use variables in microflows to complete your XPath constraints.
All in all, if you're coming from a background where you've used XML XPath, you will probably pick up the Mendix style of writing XPath constraints rather quickly.