how to parse a xml in erlang? - parsing

Question

I have this string with xml extract in a tuple list:
MessageResponse = [{"code",0},{"description","description"},{"respuestaServicioSoap",{{"executeWebServiceSolutionResult",{{"CEDULARUCSpecified", false},{"AUTORIZACION", "00000012431781"},{"AUTORIZACIONSpecified",true},{"RESULTADO","000"},{"CODIGO_RESULTADOSpecified",true},{"COD_PAGO","00000012431781"},{"COD_PAGOSpecified",true},{"COMISION",{{"string","0"}}},{"COMISIONSpecified", true},{"DIRECCIONSpecified", false},{"FECHA_COMPENSACIONSpecified", false},{"FECHA_TRANSACCION","20170116"},{"FECHA_TRANSACCIONSpecified",true},{"FECHORA_SW","20170116123951"},{"FECHORA_SWSpecified",true},{"HORA_TRANSACCION","123951"},{"HORA_TRANSACCIONSpecified",true},{"MENSAJE","TRANSACCION OK"},{"MENSAJESpecified",true},{"NOMBRESpecified",false},{"PRODUCTO","0010761005"},{"PRODUCTOSpecified",true},{"SECUENCIA_ADQ","2833"},{"SECUENCIA_ADQSpecified",true},{"SECUENCIA_SW","576167"},{"SECUENCIA_SWSpecified",true},{"TERMINAL","0696069603000001"},{"TERMINALSpecified",true},{"TYPE_TRNSpecified",false},{"VALOR_TOTAL", { { "string", "0" }}},{"VALOR_TOTALSpecified",true},{"XML_ADDSpecified",false},{"XML_DATASpecified",false},{"XML_FACT","<XML_FACT>\r\n <DATOS_FACT>\r\n <LINEA_1>REPRESENTACIONES ORMAN S.A.</LINEA_1>\r\n <LINEA_2>RUC: 0987654321</LINEA_2>\r\n <LINEA_3 />\r\n <LINEA_4 />\r\n <LINEA_5>FACTURA: 001-627-0000048745</LINEA_5>\r\n <LINEA_6>CLAVE: </LINEA_6>\r\n <LINEA_7>COMISION POR SERVICIO</LINEA_7>\r\n <LINEA_8>RECAUDACION EEAAPP - CUENTA: 11223344</LINEA_8>\r\n <LINEA_12>FACTURA: 001-627-0000048745 - CONSULTE SU DOCUMENTO EN WWW.LITO.COM/DOCUMENTOSELECTRONICOS</LINEA_12>\r\n <MSGCOMP />\r\n <MSGFACT />\r\n </DATOS_FACT>\r\n</XML_FACT>"},{"XML_FACTSpecified",true},{"XML_REPLY_CONSULTASpecified",false},{"XML_REPLY_PAGOSSpecified",false}}},{"executeWebServiceSolutionResultSpecified", true}}},{"result", "ok"}]
and need to get the text in LINEA_5 tag, any idea how to do it?

Answer 1

with this code:
{Xml, _Rest} = xmerl_scan:string(XmlFactura).
[#xmlText{value=Linea5}] = xmerl_xpath:string("//LINEA_5/text()", Xml).

Answer 2

the OTP library xmerl provides all the functions to manipulate XML files or string. It provides a set of record that help to handle different elements.
documentation is available here
The records are defined in erlXX/lib/xmerl-YYY/include/xmerl.hrl:
#xmlText{}
#xmlElement{}
#xmlPI{}
#xmlComment{}
#xmlDecl{}
[edit]
The xml data that you provide in your example is already modified, so I take an example from my own. Consider an xml file with the content:
<?xml version="1.0" encoding="UTF-8"?> <package xmlns="http://www.idpf.org/2007/opf" version="2.0" unique-identifier="uuid_id">
<metadata xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:opf="http://www.idpf.org/2007/opf" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:calibre="http://calibre.kovidgoyal.net/2009/metadata" xmlns:dc="http://purl.org/dc/elements/1.1/">
<dc:creator opf:role="aut" opf:file-as="Ahern, Cecelia">Cecelia Ahern</dc:creator>
<dc:publisher>J'ai Lu</dc:publisher>
<meta name="calibre:title_sort" content="Si tu me voyais maintenant"/>
<dc:description>description blah blah</dc:description>
<meta name="calibre:timestamp" content="2012-03-18T18:04:20+00:00"/>
<dc:title>Si tu me voyais maintenant</dc:title>
<meta name="cover" content="cover"/>
<dc:date>2012-03-18T18:04:23+00:00</dc:date>
<dc:contributor opf:role="bkp">calibre (0.8.42) [http://calibre-ebook.com]</dc:contributor>
<dc:identifier opf:scheme="ISBN">9782290006504</dc:identifier>
<dc:identifier id="uuid_id" opf:scheme="uuid">7d062b17-258e-4268-9d46-a753c063c969</dc:identifier>
<dc:subject>Chick-lit</dc:subject>
<meta name="calibre:user_categories" content="{}"/>
<meta name="calibre:author_link_map" content="{"Cecelia Ahern": ""}"/>
<dc:language>fr</dc:language>
</metadata>
<manifest>
<item href="cover.jpeg" id="cover" media-type="image/jpeg"/>
</manifest>
<spine toc="ncx">
<itemref idref="titlepage"/>
</spine>
<guide>
<reference href="titlepage.xhtml" type="cover" title="Cover"/>
</guide> </package>
It is extract from an epub book, and stored in a file "content.opf". If I want to get the author name (line 4) I can do:
1> rr("C:\\My programs\\erl8.2\\lib\\xmerl-1.3.12\\include\\xmerl.hrl").
2> {Xml,_} = xmerl_scan:file("../doc/content.opf"),
2> Content = Xml#xmlElement.content,
2> [MetaRec] = [X || X <- Content, X#xmlElement.name == metadata],
2> Meta = MetaRec#xmlElement.content,
2> [CreatRec] = [X || X <- Meta, X#xmlElement.name == 'dc:creator'],
2> Creat = CreatRec#xmlElement.content,
2> [CreatText] = [X || X <- Creat, is_record(X,xmlText)],
2> Aut = CreatText#xmlText.value.
"Cecelia Ahern"