ISSUE-33: How can rr:template be used in an ObjectMapClass to produce IRI's or Strings

rr:template type in ObjectMapClass

How can rr:template be used in an ObjectMapClass to produce IRI's or Strings

Raised by:
David McNeil
Opened on:
From section A.2.2.2 of the R2RML spec

rr:predicateMap [ rr:predicate emp:jobtype ];
rr:objectMap [ rr:template "{job}" ]

This leads to the question: in an ObjectMapClass what is to be the datatype of the value produced by an rr:template expression? Choices I can think of are:

1) IRI - this leads to the question of how to use a template to produce a string? One would expect to use rr:termtype for this, but section makes it clear that rr:termtype & rr:datatype are "relevant in an ObjectMap only if rr:column property is present as well". Another possibility is to require the user to create a SQLQuery that implements the desired template behavior in a projected column. Then the rr:termtype & rr:datatype properties can be used. But this seems like it is requiring the user to jump through unnecessary hoops.

2) String - then how to use a template to produce an IRI?

My recommendation is to clarify in the spec, in the context of an ObjectMapClass whether rr:template produces an IRI or a string and to allow rr:termtype and rr:datatype to be used in conjunction with rr:template.
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  1. ISSUE-33 (rr:template type in ObjectMapClass): How can rr:template be used in an ObjectMapClass to produce IRI's or Strings [R2RML] (from on 2011-03-10)

Related notes:

There was agreement that this needs to be changed. The termtype and datatype properties are intended to be used with the template property as well. Richard suggested a general refactoring of the spec to remove some of the parallelism. For the immediate needs to publish the spec, Souri will update sections and

David McNeil, 22 Mar 2011, 16:37:47

R2RML Spec has been modified to take care of this.
Ashok Malhotra March 22, 2011

Ashok Malhotra, 22 Mar 2011, 17:37:38

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Ashok Malhotra <>, Michael Hausenblas <>, Chairs, Eric Prud'hommeaux <>, Ivan Herman <>, Staff Contacts
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