Rails form get input value before submitting - ruby-on-rails

Question

I have a rails form which is separated in 3 steps, the first step is for the date selected, second step the time select and last step user info's.
Here is the form code :
<%= form_for [#school, Meeting.new], html: { id: 'meeting_form' } do |f| %>
<!-- one step -->
<div class="step">
<section class="container">
<div class="row">
<div class="col-md-6">
<div class="form-group">
<div class="input-group date" id="datetimepicker1">
<%= f.text_field :date, class: 'form-control date_value', :required => true %>
<span class="input-group-addon">
<span class="glyphicon glyphicon-calendar"></span>
</span>
</div>
</div>
</div>
</div>
</section>
<button type="button" class="btn btn-primary next-step" style="width: 100%;"> Suite </button>
</div>
<!-- end one step -->
<!-- second step -->
<div class="step">
<section class="container">
<div class="row">
<div class='col-sm-6'>
<div class="form-group">
<div class='input-group date' id='datetimepicker2'>
<%= f.hidden_field :mhour, required: true, class: "Vroomvroom-timepicker--value-js", :value => "" %>
<div class="scheduler--picker">
<% for time in 8..20 %>
<% if time < 10 %>
<div class="scheduler--picker-line-item <% if #school.meeting_already_booked?("0#{time}:00") %>scheduler--picker-line-item--disabled <% end %>" data-value="0<%= time %>:00">
<p>0<%= time %>:00</p>
</div>
<% else %>
<div class="scheduler--picker-line-item <% if #school.meeting_already_booked?("#{time}:00") %>scheduler--picker-line-item--disabled <% end %>" data-value="<%= time %>:00">
<p><%= time %>:00</p>
</div>
<% end %>
<% end %>
</div>
</div>
</div>
</div>
</div>
</section>
<button type="button" class="btn btn-primary previous-step" style="width: 49%;"> Retour </button>
<button type="button" class="btn btn-primary next-step" style="width: 49%;"> Suite </button>
</div>
<!-- end second step -->
<!-- third step -->
<div class="step">
<section class="container">
<div class="row">
<div class='col-sm-6' style="padding-left: 0;">
<div class="form-group">
<label for="name"> Nom </label>
<%= f.text_field :name, html: 'form-control', :required => true, placeholder: 'Votre nom de famille' %>
</div>
<div class="form-group">
<label for="firstname"> Prénom </label>
<%= f.text_field :firstname, html: 'form-control', :required => true, placeholder: 'Votre prénom' %>
</div>
<div class="form-group">
<label for="email"> Adresse email </label>
<%= f.email_field :email, html: 'form-control', :required => true, placeholder: 'Votre adresse mail, ex: jean.marc#gmail.com' %>
</div>
<div class="form-group">
<label for="phone"> Numéro de téléphone</label>
<%= f.text_field :phone, html: 'form-control', :required => true, placeholder: 'Votre numéro de téléphone, ex: 0606060606', :maxlength => 14 %>
</div>
<div class="form-group">
<label> Pour quel type de permis : </label>
<%= f.select :category do %>
<option value="code">Code uniquement</option>
<option value="moto">Permis A (moto)</option>
<option value="voiture">Permis B (voiture)</option>
<option value="am">Permis AM </option>
<option value="formation">Formations 125 cm3 </option>
<option value="autre">Une autre formation</option>
<% end %>
</div>
</div>
</div>
</section>
<button type="button" class="btn btn-primary previous-step" style="width: 49%;"> Retour </button>
<%= button_tag 'Envoyer', :type => :submit, :class => 'btn btn-primary end' %>
</div>
<!-- end thirs step -->
<% end %>
for the date picker, I use bootstrap-datetimepicker for rails, but I create my own time picker, generated with div and data-attributes. I need to get the value of date before submitting the form to know which hours are already taken in DB to disable them.
I have created a method in the model School:
# meetings
def meeting_already_booked?(date, hour)
if Meeting.where(:date => date).where(:time => hour)
return true
else
return false
end
end
And I use the method here :
<div class="scheduler--picker-line-item <% if #school.meeting_already_booked?("0#{time}:00") %>Vroomvroom-scheduler--picker-line-item--disabled <% end %>" data-value="0<%= time %>:00">
I have the time, but I need the date that user selects the step just before to search in my DB if this hour is already taken.

Answer 1

Your best bet is to save the date locally on click of next button, something like
$("#next_step_button").on("click", function(event) {
localStorage.setItem("date", $(#datetimepicker1).val());
});
To get the value back,
localStorage.getItem("date");