MongoDB add values to array if not exists

Question

I have this collection :

{
username : "user1",
arr : [
    {
        name : "test1",
        times : 0
    },
    {
        name : "test2",
        times : 5
    }
]
}

I have an array with some object. This objects have a name and the value times. Now I want to add new objects, if my array doesn't contain them. Example:

I have this two objects with the name "test1" and "test2" already in the collection. I want now to insert the objects "test2", "test3" and "test4". It should only add the object "test3" and "test4" to the array and not "test2" again. The value times doesn't do anything in this case, they should just have the value 0 when it gets insert.

Is there a way to do this with one query?

Answer 1

If you can insert test1, test2,... one by one, then you can do something like this.

db.collection.update(
{username : "user1", 'arr.name': {$ne: 'test2'}}, 
{$push: {
     arr: {'name': 'test2', 'times': 0}
   }
})

The $ne condition will prevent the update if the name is already present in arr.