Use OPTIONAL in SPARQL CONSTRUCT query

Question

I'm trying to create a graph with all the related predicates and objects. To illustrate, I have the instance ex:First_Civil_War and now I want all predicates and objects to be shown in the graph. I have done this in the following way.

construct { 
} where { 
    ex:Fourth_Conquest_of_Gaul ?p ?o
} limit 100

However, I want to exclude some of the predicates, for example ex:hasActor. How would I go about this, as the OPTIONAL statement does not work within a CONSTRUCT query.

why does OPTIONAL not work? You can put any SPARQL query into the WHERE part. I also don't see how OPTIONAL is used to exclude triples, that would be more the task of a FILTER — UninformedUser
– UninformedUser, Commented Jun 25, 2022 at 8:54
There is nothing in the template part CONSTRUCT {} so it returns the empty graph. Put in the triple patterns you want returned - but not the word OPTIONAL. You can add triple patterns with variables used in an OPTIONAL clause in the WHERE part. The triple template is skipped if a variable is unbound. — AndyS
– AndyS, Commented Jun 25, 2022 at 11:42

Joshua Taylor · Accepted Answer · 2022-06-27 18:42:19Z

1

construct { 
} where { 
   ex:Fourth_Conquest_of_Gaul ?p ?o
} limit 100 
However, I want to exclude some of the predicates, for example ex:hasActor. How would I go about this, as the OPTIONAL statement does not work within a CONSTRUCT query.

As noted in the comments, you have an empty template (construct {} where...), but you're probably looking for a plain construct where { .... If you're looking to filter out certain values of ?p, you can use FILTER in the where part. E.g.:

construct where {
  ex:Fourth_Conquest_of_Gaul ?p ?o
  filter ( ?p != ex:hasActor )
} limit 100

answered Jun 27, 2022 at 18:42

Joshua Taylor

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Mohamed Kalif.M · Accepted Answer · 2022-06-29 21:06:28Z

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As noted in the comments, you have an empty template (construct {} where...), but you're probably looking for a plain construct where { .... If you're looking to filter out certain values of ?p, you can use FILTER in the where part. E.g.:

answered Jun 29, 2022 at 21:06

Mohamed Kalif.M

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