Rails - How to remove the last comma in a hash - ruby-on-rails

Question

I have a each :
{
"type": "FeatureCollection",
"features": [
<% #pois.each do |poi| %>
{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [<%= poi.longitude %>, <%= poi.latitude %> ]
},
<% end %>
]
}
I want to delete the last comma for the last iteration. How can I do ?
It's not a json, but a Geojson.
I would have something like this :
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [2.484957, 44.6044089 ]
},
"properties": {}
},
{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [2.3749903, 44.5656783 ]
},
"properties": {}
}
]
}
All it's ok, I just want delete the last comma ;)

Answer 1

As you are probably interested in transforming an array into another array, you can use map instead of each, i.e.,
{
"type": "FeatureCollection",
"features":
<% #pois.map do |poi| %>
{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [<%= poi.longitude %>, <%= poi.latitude %> ]
}
}
<% end %>
}

Answer 2

I presume you're trying to create/edit a JSON object of some sort.
You should not handle JSON objects in this manner.
Instead use the ActiveModel::Serializers
From ActiveModel::Serializers
user = User.find(1)
user.as_json
# => { "id" => 1, "name" => "Konata Izumi", "age" => 16,
# "created_at" => "2006/08/01", "awesome" => true}
ActiveRecord::Base.include_root_in_json = true
user.as_json
# => { "user" => { "id" => 1, "name" => "Konata Izumi", "age" => 16,
# "created_at" => "2006/08/01", "awesome" => true } }