Rails GPS coordinates as an array from a form input

Question

I have setup gmaps-autocomplete-rails gem in my application, and I have an UI callback that can let me set the GPS coordinates to an input

function autocompleteMap(){
        var completer;
        completer = new GmapsCompleter({
            ...
            updateUI: function(address, latLng) {
                $("#myObject_coordinates").val(
                  "["+latLng.lat()+", "+latLng.lng()+"]" 
                )
            }
        });
    }

My mongoid model accept coordinates as an array to be used with the geocoder gem. Is there a practical way to pass the lat/lng as an array via input fields ? Some SO answers suggested to use

f.text_field(:coordinates, multiple: true)

but I cannot figure out how I should fill the value so it is interpreted as an array in the controller (and preserve lat/Lng order)

Get an array from a rails form doesn't help in my case, since I am using javascript to fill a single input (or should I set it up to fill two inputs ?)

Right now with the above js function, the associated rails params becomes

params[:my_object][:coordinates] # => ["[x, y]"]
# Wanted: [x, y]

Do I have to parse the string manually as an array, or is there a trick ?

Also, this input needs to be sanitized and the numbers ocnverted to floats, any guideline, protip on how to do that "neatly" ?

Answer 1

You need to add 2 fields and you probably want to make them hidden.

View

f.hidden_field(:coordinates, multiple: true, class: 'lat', id: 'lat')
f.hidden_field(:coordinates, multiple: true, class: 'lng', id: 'lng')

JavaScript

// ...
    updateUI: function(address, latLng) {
      $('input.lat').val(latLng.lat());
      $('input.lng').val(latLng.lng());
    }
// ...

Controller

# Will receive it as an array
params[:my_object][:coordinates]               # => [x, y]