swi-prolog, odbc_prepare and findall-option

[Ben Engbers]

I' m trying to prepare a query based on information that is stored in an XML-file.

The following code runs without problems:

prepare_query(QueryFile, Q_Name, Statement) :-
  load_structure(QueryFile, QueryXML, [dialect(xml), space(remove)]),
  getDNS( QueryXML, Q_Name, DNS),
  getSelect(QueryXML, Q_Name, Select),
  getParameter(QueryXML, Q_Name, Parameters),
  % getResultNames(QueryXML, Q_Name, ResultNames),
  odbc_prepare(DNS, Select, Parameters, Statement,
    [ findall((Apl_id_n, Apl_id_b), row(Apl_id_n, Apl_id_b)) ]).

getDNS(QueryXML, Term, DNS) :-
  xpath(QueryXML, //query(@name=Term), Query),
  xpath(Query, //dns(@name=DNS_Name), _),
  odbc_connect(DNS_Name, DNS, [alias(DNS_Name)]).

getSelect(QueryXML, Term, Select) :-
  xpath(QueryXML, //query(@name=Term)/select(text), Select).

getParameter(QueryXML, Term, Parameters) :-
  xpath(QueryXML, //query(@name=Term)/parameter_type, P_Type),
  findall(Par, xpath(P_Type, //parameter(text), Par), Parameters).

getResultNames(QueryXML, Term, ResultNames) :-
  xpath(QueryXML, //query(@name=Term)/result, Res),
  findall(Result, xpath(Res, //column/name(text), Result), Results),
  maplist(firstCharUp, Results, ResultNamesList),
  atomic_list_concat(ResultNamesList, ', ',ResultNames) .

Name and type from the selected fields are stored in the XML-file.

The predicate getResultNames returns these names (in this case apl_id_n and apl_id_b)  as an atom 'Apl_id_n, Apl_id_b' so I understand why the following code


FindAllOption =.. [findall,(ResultNames),row(ResultNames)], writeln(FindAllOption)

returns:

findall(Apl_id_n, Apl_id_b,row(Apl_id_n, Apl_id_b))

which gives an error in SWI-prolog.

Is it possible to split up ResultNames in the separated terms and to add the extra parentheses so FindAllOption is created as:


findall((Apl_id_n, Apl_id_b),row(Apl_id_n, Apl_id_b))

Is there another way to make the findall-option more flexible?

Ben