[feature request] Add option to clear the data before or after the firebase request is complete

[wujekbogdan]

Let's assume that I have bound a collection to this.posts and initialized the collection with an empty array. At the moment querying the data looks as follows:

1. this.posts is an empty array on startup
2. The data is queried from Firebase
3. After the request is done this.posts is populated with the data
4. I call this.$bind('posts', /* some query here */ )
5. The data is queried from Firebase and this.posts array is set to []
6. After the request is done this.posts populated with the data

At the 5th step, the collection is set to []. If the data is displayed on the template (which usually happens ;)), then view re-renders, so for a fraction of a second, the list of posts is empty.

It would be great if this behaviour was configurable - if we could set whether we want to clear the data before or after a firebase request is complete.

Is there any workaround? The only thing that comes to my mind is to use Vuex. But for small apps, Vuex is usually an unnecessary overkill.

[posva]

Duplicate of #83