Clash Royale CLAN TAG

SPARQL multi graph request and sort (Virtuoso 7)

Is it possible to easily make a CONSTRUCT request where I would be able to check data in different graphs AND sort them by "graph preference"?

CONSTRUCT

Let's say I sell products. For each product, I may have different suppliers, so that my setup would look like this:

graph:supplier1
<data/product/1> <http://purl.org/goodrelations/v1#hasCurrencyValue> "10" .

graph:supplier2
<data/product/1> <http://purl.org/goodrelations/v1#hasCurrencyValue> "8" .
<data/product/2> <http://purl.org/goodrelations/v1#hasCurrencyValue> "5" .


For each product specification, I want it from (graph) supplier1, then from (graph) supplier2 if not found in (graph) supplier1.

supplier1

supplier2

supplier1

This is what I've come up to:

CONSTRUCT
{
<data/product/1> ?p ?o .
}
WHERE
{
GRAPH <graph:supplier1>
{
OPTIONAL
{
<data/product/1> ?p1 ?o1 .
}
}
GRAPH <graph:supplier2>
{
OPTIONAL
{
<data/product/1> ?p2 ?o2 .
}
}
BIND (IF (BOUND(?p1), ?p1, IF (BOUND(?p2), ?p2, UNDEF)) AS ?p)
BIND (IF (BOUND(?o1), ?o1, IF (BOUND(?o2), ?o2, UNDEF)) AS ?o)
}


It does work pretty nice if I know what I'm looking for. Now if I consider:

CONSTRUCT
{
<data/product/1> ?p ?o . ?o ?cp ?co
}
WHERE
{
GRAPH <graph:supplier1>
{
OPTIONAL
{
<data/product/1> ?p1 ?o1 .
OPTIONAL { ?o1 ?cp1 ?co1 . }
}
}
GRAPH <graph:supplier2>
{
OPTIONAL
{
<data/product/1> ?p2 ?o2 .
OPTIONAL { ?o2 ?cp2 ?co2 . }
}
}
BIND (IF (BOUND(?p1), ?p1,IF (BOUND(?p2), ?p2, UNDEF)) AS ?p)
BIND (IF (BOUND(?o1), ?o1,IF (BOUND(?o2), ?o2, UNDEF)) AS ?o)
BIND (IF (BOUND(?cp1), ?cp1,IF (BOUND(?cp2), ?cp2, UNDEF)) AS ?cp)
BIND (IF (BOUND(?co1), ?co1,IF (BOUND(?co2), ?co2, UNDEF)) AS ?co)
}


Sometimes it doesn't work because I explicitly BIND ?o, and ?o may not be an Object —

BIND

?o

?o

Virtuoso RDF01 Error Bad variable value in CONSTRUCT: "1532610063"
(tag 189 box flags 0) is not a valid subject, only object of a triple
can be a literal

I don't seem to find anyone trying to sort data by "graphs" and I'm struggling trying to find an "easy" way to do it.
I've tried with SELECT and FROM NAMED, but you've still to manually select data from the graph you want.

SELECT

FROM NAMED

If anyone can help, it is more than welcome.

Thank you.

OPTIONAL

COALESCE

BIND ... IF

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