QtQuick LocalStorage database version mismatch (missing "Version" attribute in ini file) - qt

Question

I am using QtQuick/QML/Qt5.2.1 on Android. I also tested this issue on the Desktop rather than Android and I see the same problem.
I use LocalStorage to persist application data after the application closes.
I open a database using openDatabaseSync:
var db = LocalStorage.openDatabaseSync(
"TestDB",
"1.0", <-- version
"Test Database",
1000000,
function(db) {
createSchema(db);
populateData(db);
}
);
If the database does not exist and was created, the callback function gets executed and in that case I create the database schema and populate the initial dataset.
The next time the application starts, obviously I want to keep the database as-is and not recreate it.
The problem is when I restart the application I get this error:
Error: SQL: database version mismatch
If I inspect the .ini file that was created when the database was created the first time the application was run, I see this:
[General]
Description=Test Database
Driver=QSQLITE
EstimatedSize=1000000
Name=TestDB
Version=
You can clearly see a problem here is that the "Version" attribute is empty.
When the application starts up, it compares the requested version "1.0" against this empty string "" and fails.
I can fake it to get it to work of course by specifying the version as "", or by fixing the ini file - that at least tells me the code is otherwise correct - but clearly that's not a solution.
So, did I miss something or is this a Qt bug?

Answer 1

You can set the database version after creating it:
var db = LocalStorage.openDatabaseSync(
"TestDB",
"1.0",
"Test Database",
1000000,
function(db) {
createSchema(db);
populateData(db);
db.changeVersion("", "1.0");
}
);
Since the callback function will only be called it the database doesn't exists, and the changeVersion function will only work if current version is "" (otherwise, exception is thrown), I believe it's safe to use it.
EDIT: Maybe this is the intended behaviour... from LocalStorage source code, line 700:
if (dbcreationCallback)
version = QString();
So, maybe you really need to set db version after you create your tables... before you do that on the callback, it's just an empty database, and shouldn't really have a version.

Answer 2

set the attributes like this in your above code
// db = LocalStorage.openDatabaseSync(identifier, version, description, estimated_size, callback(db))
LocalStorage.openDatabaseSync("kMusicplay", "0.1", "kMusicPlay app Ubuntu", 10000);
where
'kMusicplay' is appname ,
'0.1' is version ,
'kMusicPlay app Ubuntu' is app discription
and '10000' is size of database