Native Development

[gdev001]

Hi,

I have some JSON data which I import into a QVariantList, and using code below

I am trying to traverse this list and print out the items. But I have two issues:

   JsonDataAccess jda;
   QString path;
   path = QDir::currentPath() +
         "/app/native/assets/employees.json";
   QVariant list = jda.load(path);

   QVariantList temp = list.value<QVariantList>();
   for (int i = 0; i < temp.size(); ++i) {
       QString gStr = temp[i].toString();
       qDebug()<<"String Value: "<<gStr;
   }

 1. How to use qDebug properly in Momentics IDE? OS: Mac OS X; nothing gets printed even if I remove the gStr variable from that line

2. Is it correct way to traverse the QVariantList and print contents of its elements?

ps. the temp is correctly initialized I manage to fill a ListView using it later on.

[Zmey · Accepted solution]

Hi,

1. Please check "Known limitations" section in SDK release notes, it contains information on setting up the logs:

https://developer.blackberry.com/cascades/download/releasenotes/

2. The code is correct. Another way to iterate the list:

foreach (QVariant v, temp)
{
  qDebug() << "String Value: " << v.toString() << "\n";
}

You might also want to add newline to flush the output otherwise last line can be lost on application crash.

Also foreach makes a copy of list before iterating. Qt performs lazy copying of data (copy-on-write), so this isn't very expensive and you can safely modify the container during iteration.

[gdev001]

Yep, thanks. just one brief question. In my case it appears my "temp" is an array of 3 objects. Where clearly each object is a QVariantMap. Now I want to print out the contents of some keys (say "key1") in these QVariantMaps objects. do you have some code snippet that would do this? ps. I actually have issues converting the QVariantList item to a QVariantMap; I know how to print contents of a QVariantMap

[Zmey]

QVariantMap m = v.value<QVariantMap>();
qDebug() << m["key"].toString();

[gdev001]

Yes I was about to write I had found a similar solution; but now my debug logging is not working.. a anyway thanks I will try to find smth.