xml - 如何正确使用 QXmlQuery？ (Qt XQuery/XPath)

Question

我正在使用以下代码加载 XML 文件(实际上是 NZB):

QXmlQuery query;
query.bindVariable("path", QVariant(path));

query.setQuery("doc($path)/nzb/file/segments/segment/string()");
if(!query.isValid())
    throw QString("Invalid query.");

QStringList segments;
if(!query.evaluateTo(&segments))
    throw QString("Unable to evaluate...");

QString string;
foreach(string, segments)
    qDebug() << "String: " << string;

使用以下输入，它按预期工作:

<?xml version="1.0" encoding="iso-8859-1" ?>
<!DOCTYPE nzb PUBLIC "-//newzBin//DTD NZB 1.0//EN" "http://www.newzbin.com/DTD/nzb/nzb-1.0.dtd">
<nzb>
    <file>
        <groups>
            <group>alt.binaries.cd.image</group>
        </groups>
        <segments>
            <segment>waWdnZFHevdBeZTUnZ2dnUVZ8uOdnZ2d@giganews.com</segment>
        </segments>
    </file>
</nzb>

但是，对于以下输入，不会返回任何结果。这是输入应该如何格式化，具有属性:

<?xml version="1.0" encoding="iso-8859-1" ?>
<!DOCTYPE nzb PUBLIC "-//newzBin//DTD NZB 1.0//EN" "http://www.newzbin.com/DTD/nzb/nzb-1.0.dtd">
<nzb xmlns="http://www.newzbin.com/DTD/2003/nzb">
    <file poster="test@test.test" date="1225385180" subject="ubuntu-8.10-desktop-i386 - ubuntu-8.10-desktop-i386.par2 (1/1)">
        <groups>
            <group>alt.binaries.cd.image</group>
        </groups>
        <segments>
            <segment bytes="66196" number="1">waWdnZFHevdBeZTUnZ2dnUVZ8uOdnZ2d@giganews.com</segment>
            <segment bytes="661967" number="1">waWdfhrgfnZFHevdBeZTUnZ2dnUVZ8uOdnZ2d@giganews.com</segment>
        </segments>
    </file>
</nzb>

有人可以告诉我我做错了什么吗？

Answer 1

我发现这是因为我需要提供一个默认命名空间，这花了几个小时才弄清楚...

现在的查询是:

declare default element namespace "http://www.newzbin.com/DTD/2003/nzb";
declare variable $path external;
doc($path)/nzb/file/segments/segment/string()