Unable to parse tutorial example with rmlmapper

[ldesousa]

A very simple data source:

$ cat Persons.csv
firstname,
Mary,
John,

And a transformation similar to that provided in the Matey tutorial:

$ cat person.yarrrml
prefixes:
 ex: "http://example.com/"

mappings:
  person:
    sources:
      - ['Persons.csv~csv']
    s: http://example.com/$(firstname)
    po:
      - [a, foaf:Person]
      - [ex:name, $(firstname)]

I tested this pairing in Matey and it functions correctly, however, with rmlmapper it fails:

$ rmlmapper -m person.yarrrml
13:00:59.676 [main] ERROR be.ugent.rml.cli.Main               .run(267) - Unable to parse mapping rules as Turtle. Does the file exist and is it valid Turtle?
org.eclipse.rdf4j.rio.RDFParseException: Namespace prefix 'prefixes' used but not defined [line 1]
	at org.eclipse.rdf4j.rio.helpers.RDFParserHelper.reportFatalError(RDFParserHelper.java:347)
	at org.eclipse.rdf4j.rio.helpers.AbstractRDFParser.reportFatalError(AbstractRDFParser.java:683)
	at org.eclipse.rdf4j.rio.turtle.TurtleParser.reportFatalError(TurtleParser.java:1309)
	at org.eclipse.rdf4j.rio.helpers.AbstractRDFParser.getNamespace(AbstractRDFParser.java:281)
	at org.eclipse.rdf4j.rio.turtle.TurtleParser.parseQNameOrBoolean(TurtleParser.java:1004)
	at org.eclipse.rdf4j.rio.turtle.TurtleParser.parseValue(TurtleParser.java:574)
	at org.eclipse.rdf4j.rio.turtle.TurtleParser.parseSubject(TurtleParser.java:398)
	at org.eclipse.rdf4j.rio.turtle.TurtleParser.parseTriples(TurtleParser.java:333)
	at org.eclipse.rdf4j.rio.turtle.TurtleParser.parseStatement(TurtleParser.java:203)
	at org.eclipse.rdf4j.rio.turtle.TurtleParser.parse(TurtleParser.java:165)
	at org.eclipse.rdf4j.rio.turtle.TurtleParser.parse(TurtleParser.java:128)
	at be.ugent.rml.store.RDF4JStore.read(RDF4JStore.java:120)
	at be.ugent.rml.cli.Main.run(Main.java:264)
	at be.ugent.rml.cli.Main.main(Main.java:46)

I am doing something wrong? Thank you for reading.

[DylanVanAssche]

Hi! Thanks for using Matey, YARRRML, RML and the RMLMapper!

Matey is a YARRRML web based editor which uses the yarrrml-parser to transform YARRRML into RML mapping rules.
After that, it let the RMLMapper execute the RML mapping rules.
The RMLMapper on its own cannot parse YARRRML files, you first need to convert it it to RML with yarrrml-parser:

npm i -g @rmlio/yarrrml-parser
yarrrml-parser -i person.yarrrml -o person.rml.ttl

If you feed then the RMLMapper the person.rml.ttl file, it should work.

[ldesousa]

Thank you for the swift reply. Unfortunately, npm fails to install yarrrml-parser on my system. Before I start tinkering around, is there a manual for that particular tool?

Better still, is it possible to install yarrrml-parser without having to install npm? Like with rmlmapper.

Thank you.

[dachafra]

You can use the online mapping editor (https://rml.io/yarrrml/matey/) to translate the mappings, or if you prefer you can test YARRRML-translator in python (https://github.com/oeg-upm/yarrrml-translator). The latter is still ongoing development