I have two DataObject-Sets:

$set1 = DataObject::get('Visualisierung','Favorit = 1', 'RAND()');
$set2 = DataObject::get('Visualisierung','Favorit = 0', 'RAND()');

Now i want to merge these two to iterate them later in the template.
In SS 2.4 The Following worked:

$set1->merge($set2);

Now with SS3 i get the following error Message:
[User Error] Can't call DataList::merge() because its data comes from a specific query.

What is my error here?

If i use
$newSet = DataObject::merge($set1, $set2);

I get an Error that the expected Object Class is wrong. (It expects the Page Class but i wanna merge pulled DataObjects)

With 3.0 and the lazy-loading ORM, you can't merge two DataLists. As your case is simple, you can simply use $set = Visualisierung::get()->filter('Favorit', array(1, 0))->sort('RAND()');

Unfortunately that does not produces the result i want. It just Randomizes ALL the Objects...

I try to achieve the following:
The First few Objects should be all "Favorite=1" in Random Order.
Followed by all Objects with "Favorite=0" in random Order

I think i will have to handle this in the template now if it is no more possible with the ORM... (Seems it has less features than before?)

In that case, you want Visualisierung::get()->filter('Favorit', array(1, 0))->sort('Favorit', 'desc')->sort('RAND()');

If you really need to run them separately then merge, you can use something like:

$set = new ArrayList;
foreach(Visualisierung::get()->filter('Favorit', 1)->sort('RAND()') as $obj) $set->push($obj);
foreach(Visualisierung::get()->filter('Favorit', 0)->sort('RAND()') as $obj) $set->push($obj);
return $set;

which is pretty much what was happening in 2.4.

I really needed to run them seperately.

object-> push works perfect!

On http://klarbild.probiermau.ch/ you can see how i use it...
First are all "Favorite=1" Objects(Picture shown) in Random Order.
The last two Rows are all "Favorite=0" Visualisierung Objects in Random Order.

Simon_w you are officially my hero for today!

Thanks a lot for your kind help!