Specify data types with rdflib.js

yova · January 28, 2019, 8:38am

Hi guys,

I’m wondering how to specify a data type for properties with rdflib.js.

I.e. I’d like to define the current year as xsd:gYear.

Currently the statements are serialized as:

:validPeriod a time:DateTimeDescription; time:year 2019 .

But I like to serialize them like

:validPeriod a time:DateTimeDescription; time:year "2019"^^xsd:gYear .

as described in the owl-time docs.

Any hints?

pheyvaer · January 28, 2019, 8:45am

Does the following work?

x = $rdf.literal('2019', undefined, XSD('gYear'))

(source)

yova · January 28, 2019, 9:48am

This runs without error, but the type is not serialized. The property is a string now:

:validPeriod a time:DateTimeDescription; time:year "2019".

yova · July 30, 2019, 9:20am

The documentation on

regarding this is wrong:

github.com/linkeddata/rdflib.js

Literal datatype definition unclear / undocumented

opened 09:19AM - 30 Jul 19 UTC

y0va

According to the [documentation](https://github.com/solid/solid-tutorial-rdflib.…js#rdf-term-types) typed literals should be created with `literal(value,undefined, datatype)`. This does not work in `rdflib 0.20.3`. You need to use `new Literal(value, undefined, dataype)` or explicitly set the datatype: ```JS const $rdf = require('rdflib'); const testtype = new $rdf.NamedNode('http://www.w3.org/2001/XMLSchema#gYear') let test = new $rdf.Literal('2019', undefined, testtype) console.log(); console.log(`Datatype:\n${JSON.stringify(testtype,null,4)}\n\n`); console.log(`Literal created with class call:\n${JSON.stringify(test,null,4)}\n\n`); test = $rdf.literal('2019', undefined, testtype) console.log(`literal created with function call:\n${JSON.stringify(test,null,4)}`) test.datatype=testtype console.log(`Literal after explicitly setting datatype:\n${JSON.stringify(test,null,4)}`) const FOAF = $rdf.Namespace("http://xmlns.com/foaf/0.1/") const iri = new URL('http://example.org/name/name') let sts = [] let graph = new $rdf.graph() sts.push(new $rdf.Statement($rdf.Namespace(iri.href)('#notme'),FOAF('name'), 'Meier')) sts.push(new $rdf.Statement($rdf.Namespace(iri.href)('#notme'),FOAF('birthday'), test)) graph.addAll(sts) console.log($rdf.serialize(undefined, graph, 'http://example.org/name/', 'text/turtle')) ``` ### Output: ``` Datatype: { "termType": "NamedNode", "value": "http://www.w3.org/2001/XMLSchema#gYear" } Literal created with class call: { "termType": "Literal", "value": "2019", "datatype": { "termType": "NamedNode", "value": "http://www.w3.org/2001/XMLSchema#gYear" } } literal created with function call: { "termType": "Literal", "value": "2019" } Literal after explicitly setting datatype: { "termType": "Literal", "value": "2019", "datatype": { "termType": "NamedNode", "value": "http://www.w3.org/2001/XMLSchema#gYear" } } @prefix : <#>. @prefix n: <name#>. @prefix n0: <http://xmlns.com/foaf/0.1/>. @prefix XML: <http://www.w3.org/2001/XMLSchema#>. n:notme n0:birthday "2019"^^XML:gYear; n0:name "Meier". ``` ### related: - https://forum.solidproject.org/t/specify-data-types-with-rdflib-js/1156 - https://github.com/linkeddata/rdflib.js/issues/150 - https://github.com/solid/solid-tutorial-rdflib.js#rdf-term-types

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Specify data types with rdflib.js

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