I'm working with the US Census API (examples), in which there are optional parameters, which are space-separated. I needed a general-purpose URL templating mechanism, and Google led me to RFC 6570 and its implementations.
But as I understand it, RFC 6570 can't template a query substring like:
...&in=state:02+county:170&...
where "county" may be undefined and should be omitted if so, along with the preceding "+"-encoded space, to leave just
...&in=state:02&...
Can RFC 6570 encode this?
If not, is there an alternative templating syntax for general-purpose URI templating in common use I should consider that's implemented in Javascript and maybe Java?
Is use of a "+" to delimit query sub-elements, as done here, common, or extremely quirky? (I'm asking about frequency-of-use, not whether it's wise!) Is RFC 6570 too restrictive for an application where one is not in control of the URI query syntaxes used?
UPDATE
I see two problems: one is the "+" separator, and the other is the use of ":" in e.g. "state:02", which I don't see how to do either.