Export should not contain irrelevant columns

[mvanbrab]

This is the export of the result of query "My idols" from configuration "test".

name.termType,name.value,name.language,name.datatype.termType,name.datatype.value,birthDate_int.termType,birthDate_int.value,birthDate_int.language,birthDate_int.datatype.termType,birthDate_int.datatype.value,id
Literal,Sr. Isaac Newton,,NamedNode,http://www.w3.org/2001/XMLSchema#string,Literal,1643-01-04,,NamedNode,http://www.w3.org/2001/XMLSchema#string,0
Literal,Albert Einstein,,NamedNode,http://www.w3.org/2001/XMLSchema#string,Literal,1879-03-14,,NamedNode,http://www.w3.org/2001/XMLSchema#string,1

Propose to just export the values:

name,birthDate_int
Sr. Isaac Newton,1643-01-04
Albert Einstein,1879-03-14

[elsdvlee]

In my opinion, the termtype, language and datatype are useful information for expert users. However, x.datatype.TermType is a confusing column without added value and should be removed.

[mvanbrab]

OK, the new proposed export then looks like:

name.termType,name.value,name.language,name.datatype.value,birthDate_int.termType,birthDate_int.value,birthDate_int.language,birthDate_int.datatype.value,id
Literal,Sr. Isaac Newton,,http://www.w3.org/2001/XMLSchema#string,Literal,1643-01-04,,http://www.w3.org/2001/XMLSchema#string,0
Literal,Albert Einstein,,http://www.w3.org/2001/XMLSchema#string,Literal,1879-03-14,,http://www.w3.org/2001/XMLSchema#string,1

[mvanbrab]

I also noticed that the export contains an irrelevant column id. That column is added in the code to satisfy ReactAdmin for list display, but is not part of the SPARQL query variables. So I also deleted that column from the export.

In fact, id shouldn't be used as a SPARQL query variable or things will go wrong. I added a runtime test for that and mentioned in the README that it shouldn't be used as a SPARQL query variable.