Hi Martynas, A string substitution example in Python would be:
runtime_vars = ['https://test', 'https://test2'] template_query = 'VALUES ?this { UNDEF }' query = template_query.replace( "VALUES ?this { UNDEF }", f"VALUES ?this {{ { ' '.join(['<' + binding + '>' for binding in runtime_vars]) if runtime_vars else 'UNDEF'} }}" ) There's a stub HTTP server which allows saving + substituting queries in the above format here: https://github.com/Kurrawong/sparql-template-lib/blob/main/server/api.py, it uses a lark grammar for SPARQL a colleague wrote and targets the inline data (VALUES) clauses (see stl/transformers), so it's safer than the string method. You populate the templates with an "inverted" sparql results JSON i.e. bindings for the query vars including types rather than results. I think you could use ParameterizedSparqlString to do something similar https://jena.apache.org/documentation/javadoc/arq/org.apache.jena.arq/org/apache/jena/query/ParameterizedSparqlString.html#setValues(java.lang.String,java.util.Collection) . But not sure if you can set the valueName to the token UNDEF Thanks On Mon, Nov 25, 2024 at 6:43 PM Martynas Jusevičius <marty...@atomgraph.com> wrote: > Hi David, > > Yes this would work for me in this case -- I do know the variables so > I could use UNDEF as placeholders. > > Maybe you have a code snippet for this logic? :) > > Martynas > > On Mon, Nov 25, 2024 at 1:03 AM David Habgood <dcchabg...@gmail.com> > wrote: > > > > Hi Martynas, > > > > Do you know ahead of time which variable(s) you're going to be injecting > > the VALUES clause for? > > > > I've been using a pattern where I add VALUES ?this { UNDEF } in > "template" > > queries, then at runtime parse the query and replace "UNDEF" (where all > of > > the DataBlockValue < > https://www.w3.org/TR/sparql11-query/#rDataBlockValue>s > > in a binding within a InlineDataFull are "UNDEF") with a set of bindings > > supplied at runtime. This has the benefit that if you do not supply a > > binding for ?this, UNDEF means it is left unbound. > > > > Thanks, > > > > On Mon, Nov 25, 2024 at 9:40 AM Martynas Jusevičius < > marty...@atomgraph.com> > > wrote: > > > > > Hi, > > > > > > What would be the simplest way to safely (i.e. using query builder or > > > algebra) to inject a VALUES block at the beginning of a query? > > > > > > For example > > > > > > SELECT * > > > { > > > ?this ?p ?o > > > } > > > > > > should become > > > > > > SELECT * > > > { > > > VALUES ?this <http://localhost> > > > ?this ?p ?o > > > } > > > > > > after the injection. > > > > > > Thanks, > > > > > > Martynas > > > >
