How to parse xml with optional elements

问题

SEPA ISO XML transactions file needs to be parsed into flat table in Postgres 9.1+ in ASP:NET 4.6 MVC controller.

I tried code below but this produces wrong result:

endaaa            tasusumma  orderinr
XX00221059842412     150.00  PV04131
XX00221059842412       0.38  PV04131

Since there is no EndToEnd in second row there should be null or empty text in second row orderinr column:

endaaa            tasusumma  orderinr
XX00221059842412     150.00  PV04131
XX00221059842412       0.38  null

How to fix this ?

Parsing can done in other ways e.q. using xslt stylesheet for tranformation or in client side ASP.NET 4.6 MVC if this is more reasonable.

create temp table t(x xml, nsa text[][]) on commit drop;
insert into t values(
'<?xml version=''1.0'' encoding=''UTF-8''?>
<Document xmlns="urn:iso:std:iso:20022:tech:xsd:camt.053.001.02">
  <BkToCstmrStmt>
    <Stmt>
      <Acct>
        <Id>
          <IBAN>XX00221059842412</IBAN>
        </Id>
      </Acct>
      <Ntry>
        <Amt Ccy="EUR">150.00</Amt>
        <NtryDtls>
          <TxDtls>
            <Refs>
              <EndToEndId>PV04131</EndToEndId>
            </Refs>
          </TxDtls>
        </NtryDtls>
      </Ntry>
      <Ntry>
        <Amt Ccy="EUR">0.38</Amt>
        <NtryDtls>
          <TxDtls>
            <Refs>
              <AcctSvcrRef>2016080100178214-2</AcctSvcrRef>
            </Refs>
          </TxDtls>
        </NtryDtls>
      </Ntry>
    </Stmt>
  </BkToCstmrStmt>
</Document>
', ARRAY[ARRAY['ns','urn:iso:std:iso:20022:tech:xsd:camt.053.001.02']]);

SELECT 
unnest(xpath('/ns:Document/ns:BkToCstmrStmt/ns:Stmt/ns:Acct/ns:Id/ns:IBAN/text()', x,nsa))::text AS endaaa,
unnest(xpath('/ns:Document/ns:BkToCstmrStmt/ns:Stmt/ns:Ntry/ns:Amt/text()', x,nsa))::text::numeric AS tasusumma
 , unnest(xpath('/ns:Document/ns:BkToCstmrStmt/ns:Stmt/ns:Ntry/ns:NtryDtls/ns:TxDtls/ns:Refs/ns:EndToEndId/text()', x,nsa))::text AS orderinr
FROM t;

Update

Using code from Hannes answer returns empty rows in Postgres 9.1 How to make it work in 9.1 ?

Posted also in pgsql.general mailing list.

回答1:

You need to extract all ns:Ntry elements first, and then get the amount and EndToEndId for each of them:

SELECT 
    endaaa,
    (xpath('ns:Amt/text()', x,nsa))[1]::text::numeric AS tasusumma,
    (xpath('ns:NtryDtls/ns:TxDtls/ns:Refs/ns:EndToEndId/text()', x,nsa))[1] AS orderinr

FROM (
    SELECT (xpath('/ns:Document/ns:BkToCstmrStmt/ns:Stmt/ns:Acct/ns:Id/ns:IBAN/text()', x,nsa))[1] as endaaa,
    unnest(xpath('/ns:Document/ns:BkToCstmrStmt/ns:Stmt/ns:Ntry', x,nsa)) as x, nsa
    FROM t
) Ntry

来源：https://stackoverflow.com/questions/38888739/how-to-parse-xml-with-optional-elements

标签

xml

postgresql

xslt

postgresql-9.1