QXmlQuery setquery for kml file

saitej

What should be the query to get the coordinates in the kml file?

jsulm

kml is XML as far as I know. So, you can open it in a text editor and see how/where coordinates are stored and then define the query.

the_

@jsulm
Yes it is XML Structure, All coordinates can be found between <coordinates> and </coordinates> with a Long/Lat pair in each line.

mrjj

hi
This might be interersting to read
http://stackoverflow.com/questions/9675907/how-can-i-use-qts-qxmlquery-to-run-xpath-queries-on-a-local-file

it seems your sample has coordinates under LineString

so something like
query.setQuery("kml/Document/Placemark[last()]/LineString/coordinates");

saitej

@mrjj

I had checked that link before posting but I didn’ understand how the query args are written and it didn't work for my file. So I want to know how the args are written?

    query.setQuery("declare default element namespace \"http://earth.google.com/kml/2.0\"; declare variable $kmlFile external; doc($kmlFile)/kml/Document/Placemark[last()]/LineString/coordinates/text()");

Why dis doesn't work?

mrjj

@saitej said:

text()
..]/LineString/coordinates/text()")

what is that ?
seems wrong.

and you should check with
QString result;
query.evaluateTo(&result);
qDebug() << result;

what you get.

-how the args are written?
Sorry. Dont understand what u mean with that.

saitej

@mrjj
The result gives me "\n".

I meant that for any xml file, by knowing the tags and the values you want to access, how to write a query.
is this part necessary in the query

"declare default element namespace \"http://earth.google.com/kml/2.0\"; declare variable $kmlFile external;

or I can start the query with doc($kmlFile)/kml where $kmlFile is the filename

mrjj

@saitej
Ok, so u are getting close. :)

To use it , you must learn the syntax and the class
https://www.w3.org/TR/xquery/
http://doc.qt.io/qt-5/qxmlquery.html

saitej

@mrjj

From what I have understood I have made this query.

QXmlQuery query;
    query.bindVariable("kmlFile", &file);
    QString q = "declare variable $kmlFile external;doc($kmlFile)/kml/Document/Placemark/LineString/coordinates/text()";

 query.setQuery(q);

But I still get the result value as "\n"