Select collection item by element value

[kwin]

For arrays one is often interested in referencing a particular item. Current referencing is only supported by index, but often the index is unknown. In that case it would be beneficial to reference an item by selecting the first one having a particular element value for example with an XPath like syntax:

${settings.servers[id='apache'].passphrase}

[michael-o]

The statement is incomplete. Curly missing and with XPath the value must be in single quotes.

[kwin]

@michael-o Thanks, fixed above.

The current logic for collections is in

plexus-interpolation/src/main/java/org/codehaus/plexus/interpolation/object/FieldBasedObjectInterpolator.java

Line 520 in a2b39e6

interpolationTargets.add( new InterpolationTarget( value, basePath + "[" + i + "]" ) );

which just adds a target there with the index qualifier, i.e. the lookup does not actually interpret the index but just retrieves the mapping with that name. Just adding more InterpolationTargets with path containing the XPath expression does not really scale, so this seems to require a major extension of this library.