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PreparedSparqlQuery.substitute_variable() when variable is in WHERE #1837
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@ajnelson-nist Sorry for the answer lag.
This is a great question. For now substitution works following https://github.com/w3c-cg/sparql-dev/blob/main/SEP/SEP-0007/sep-0007.md i.e. it crosses
SELECTboundaries only when the variable is in theSELECT.I have opened #1848 that clarifies it a bit
Oh! This is a more nuanced issue than I thought.
It makes sense to me now that substituting in the
WHEREclause only works in a subset of all possible SPARQL queries. Thanks for linking that issue.The update in 1848 still just takes a by-fiat documentation approach; I don't really understand why I can't touch a variable in the
WHEREclause. Is it worth linking to thatsparql-devnote file for further explanation?I also had to mull over whether I could do a binding at all, but after reading your note I realized I can just "tag" the variable in the
SELECTclause. I filed #1850 on top of #1848 to help others understand this. Feedback or revisions are welcome.- added a commit that references this issue
on Aug 5, 2026
Hello,
I have a SPARQL query where I want to substitute a value in its
WHEREclause. I tried following the documentation forsubstitute_variable(rendered docs here for today's release-state), and got a runtime error whileunwrap-ing,NotExistingSubstitutedVariable.I found three
enumvariants when searching for that symbol (query results here), and they each indicate this:I admit I'm not familiar with the use case where variable substitution would happen on something in the
SELECTclause of a SPARQL query. However, I am comfortable running substitutions on variables in theWHEREclause with other frameworks.Is there another mechanism available that would let me do so? And, is this the intended design & constraint of
substitute_variable? The doc string reads:From that, I'd guess that anywhere in the query would be a fair target for substitution.