File API writing file doesn't work Samsung smart tv SDK

Question

I have this javascript code which makes possible writing in a file

{

     var fileSystemObj = new FileSystem();
     var fileObj = fileSystemObj.openCommonFile(curWidget.id + 
                                           ‘/testFile.data’, ‘w’);
     fileObj.writeLine(‘something to write.’);
     fileSystemObj.closeCommonFile(fileObj);

}

but it doesn't work. Doesn't even display any error!

Answer 1

samsung developer forum (you may not see unless you sign in... ) I am quoting it.

    case tvKey.KEY_RED:
  alert('RED BUTTON!');
  alert('CWID: '+curWidget.id);
  try {
    var fileSystemObj = new FileSystem();
    var fileObj = fileSystemObj.openCommonFile(curWidget.id+'/testFile.data','w');
    fileObj.writeLine('something to write.');
    fileSystemObj.closeCommonFile(fileObj);
  } catch (e) {
    alert('Error: file handling: '+e);
  }
  break;

lead to error: alert() : Error: file handling: TypeError: 'null' is not an object (evaluating 'fileObj.writeLine') Reading cause same problem.

and solution accepted in that link is:

I suppose that problem is that you have to create common dir (if does not exist ) at first :

var fileObj = fileSystemObj.openCommonFile(filePath, 'w');
if(!fileObj){
var bValid = fileSystemObj.isValidCommonPath(curWidget.id); 
if (!bValid) { 
        fileSystemObj.createCommonDir(curWidget.id);    
}
}
fileObj = fileSystemObj.openCommonFile(filePath, 'w');
fileObj.writeLine('something to write.');
fileSystemObj.closeCommonFile(fileObj);