optional argument to sparql queries

[eroux]

In some cases, the client might pass an argument to a query or not, both cases being valid. Consider the following use case:

construct {
 ?res adm:status ?st .
 ?res skos:prefLabel ?resL .
} where {
  ?res ?resp bdr:W19740 .
  ?res adm:status ?st .
  ?res skos:prefLabel ?resL .
}

it could be queried in two different ways:

• one is when we want to have all the entities linked to bdr:W19740 and their status (which is what an admin client would call), in which case we don't want to bind ?st
• one is when we want the entities linked to bdr:W19740 that have a status of bda:StatusReleased, in which case we want ?st to be bound to bda:StatusReleased

So there should be a way to do that. Currently a request can only take mandatory arguments.

[MarcAgate]

Implemented as of commit b61687c

In the example used for describing the issue, you would have to add in the template:

• a #QueryOptionalParams=R_st line
• rename ?st to ?R_st in the query
• add input param to the existing ones:

param.R_st.type=resource

param.R_st.subtype=a Resource IRI

param.R_st.desc=the URI of a Work resource

and finally add ?R_st=bdr:W19740 to the query string (request parameters)

see also: https://github.com/buda-base/lds-queries/blob/master/README.md