Rails reverses day and month when saving DateTimePicker form field - ruby-on-rails

Question

I am trying to use Tempus Dominus Bootstrap 4 in a form on a Ruby on Rails 5.2 app so the user can select a date. Here is the code:
app/views/events/_form.html.erb
<div class='form-group'>
<%= f.label :starts_at, 'Start Date and Time', class: 'control-label' %>
<div class="input-group date" id="datetimepicker1" data-target-input="nearest">
<%= f.text_field(:starts_at, class: "form-control datetimepicker-input", data: {target:"#datetimepicker1"}) %>
<div class="input-group-append" data-target="#datetimepicker1" data-toggle="datetimepicker">
<div class="input-group-text"><i class="fas fa-calendar-plus"></i></div>
</div>
</div>
</div>
app/assets/javascripts/events.js
$(function () {
$('#datetimepicker1').datetimepicker();
});
app/controllers/events_controller.rb
def create
#event = Event.new(event_params)
#event.user = current_user
if #event.save
redirect_to #event, notice: 'Event was successfully created.'
else
render :new
end
end
I want to submit the format with month first. When I pick a date June 9, 2018 and submit the form, it saves it to the database with the month and day reversed: Sept 6, 2018. When I look at the params after the form is submitted, the format is 06/09/2018 6:00 PM with month first, but Ruby/Rails converts it to a datetime object assuming day first.
How do I tell Ruby that the month is first when converting it to a date object? Can I do something in the controller before saving it?

Answer 1

You can tell Ruby how to read time string:
DateTime.strptime('06/09/2018', '%m/%d/%Y')
More details you can see in this answer.
Edited:
Also, you can set the default date format as there:
Add this to config/initializers/date_time.rb
Date::DATE_FORMATS[:default] = "%m/%d/%Y"

Answer 2

I found out you can change the date format to one Ruby correctly understands and that is easily readable by users. Change the JavaScript to:
$(document).on('turbolinks:load', function() {
$('#datetimepicker1').datetimepicker(
'format', 'MMMM D, YYYY h:mm A'
);
});
This will display the date to the user as June 9, 2018 6:30 PM. Date format comes from Moment.js http://momentjs.com/docs/#/displaying/format/ but is added to the format option of Tempus Dominus.
As a side note, to get tempus dominus boostrap 4 working in Rails, you have to also load moment.js. Either call the cdn or add the momentjs-rails gem. If the latter then in your application.js file you need to require it, something like this:
# app/assets/javascripts/application.js
...
//= require moment
//= require tempusdominus-bootstrap-4.js