Hey Mahmoud,
You can store arrays in Firebase, but they just won't show up as arrays. An array like [1, 2, 3] will show up as:
{
'0': 1,
'1': 2,
'2': 3
}
So you'll just have to account for the fact that your data will be in that format. There are lots of reasons why arrays aren't great for realtime databases like Firebase, many of which are discusses
in our docs.
If you are looking to do geospatial queries using Firebase, you should check out
GeoFire. We have JavaScript, iOS, and Java versions of the library, all of which play nicely with each other.
Jacob