Dart exception when upgrading IndexedDB - dart

Question

I get an exception when i try to upgrade my indexedDB database with a higher version then the browser currently has,
but the funny part abort is that, it gets upgraded. Is this by design or have i done something wrong.
I got very inspired from the dart sample Todo, so my code ended up looking like this.
void open_db(String DB_name, int Version, String Store_Name){
var request = window.indexedDB.open(DB_name, Version);
request.on.success.add((e) => _onDbOpened(request.result));
request.on.error.add((e) => print("Error opening db"));
request.on.upgradeNeeded.add((e) => _onUpgradeNeeded(request.transaction, Store_Name));
}
void _onDbOpened(IDBDatabase db){
_db = db;
print("DB opened");
}
void _onUpgradeNeeded(IDBTransaction changeVersionTransaction, String Store_Name){
changeVersionTransaction.on.error.add((e) => print("Error upgrading db"));
changeVersionTransaction.on.complete.add((e) => print("Success upgrading db"));
changeVersionTransaction.db.createObjectStore(Store_Name);
}
When I run this with version=4 and the browser only have version=3, then it jumps to _onUpgradeNeeded as expected, but I get an IDBDatabaseException with message: "ConstraintError: DOM IDBDatabase Exception 4".
So where is it I go wrong?

Answer 1

Thanks for your question!
You may need to check if the store exists first.
if (db.objectStoreNames.indexOf(storeName) == -1) {
db.createObjectStore(storeName);
}
Here is some code to update your IndexedDB database, using Dart. Note, this compensates for the two ways to upgrade (an old way that Chrome used, and the new way that Firefox and newer versions of Chrome use)
_openDb(afterOpen()) {
var request = window.indexedDB.open(DB_NAME, VERSION);
if (request is IDBOpenDBRequest) {
// New upgrade protocol. FireFox 15, Chrome 24, hopefully IE10.
request.on.success.add(expectAsync1((e) {
db = e.target.result;
afterOpen();
}));
request.on.upgradeNeeded.add((e) {
guardAsync(() {
_createObjectStore(e.target.result);
});
});
request.on.error.add(fail('open'));
} else {
// Legacy setVersion upgrade protocol. Chrome < 23.
request.on.success.add(expectAsync1((e) {
db = e.target.result;
if (db.version != '$VERSION') {
var setRequest = db.setVersion('$VERSION');
setRequest.on.success.add(
expectAsync1((e) {
_createObjectStore(db);
var transaction = e.target.result;
transaction.on.complete.add(
expectAsync1((e) => afterOpen()));
transaction.on.error.add(fail('Upgrade'));
}));
setRequest.on.error.add(fail('setVersion error'));
} else {
afterOpen();
}
}));
request.on.error.add(fail('open'));
}
}
_createObjectStore(db) {
try {
// Nuke object store if it already exists.
db.deleteObjectStore(STORE_NAME);
}
on IDBDatabaseException catch(e) { } // Chrome
on DOMException catch(e) { } // Firefox
db.createObjectStore(STORE_NAME);
}
Note, this code is from this test: http://code.google.com/p/dart/source/browse/trunk/dart/tests/html/indexeddb_3_test.dart