ActionController::ParameterMissing in Protocol::TrasmissionMeansController#create - ruby-on-rails

Question

I have a problem with this code .
This is the controller :
def create
#mean = TrasmissionMean.new(trasmission_mean_params)
if #mean.save
flash[:success] = "Mezzo di Trasmissione #{#mean.description}"
else
flash[:error] = "Error #{#mean.errors.full_messages}"
render :action => 'new'
end
end
def trasmission_mean_params
params.require(:mean).permit(:description)
end
I have a problem with this code .
This is the view , with render the form:
<div class="row">
<div class="col-md-10 col-md-offset-1">
<%= form_for #mean, :html => {:class => "form-horizontal" },:url => url_for(:controller => "trasmission_means", :action => "create" ) do |f| %>
<hr>
<%= render partial: "form", :locals => { :#mean => #mean, :f => f } %>
<hr>
<%= f.submit "Aggiungi", class: 'btn btn-success btn-lg pull-right' %>
<% end %>
</div>
</div>
the render form :
<div class="form-group">
<div class="col-lg-12">
<%= f.text_area :description, :rows => 4, class: 'form-control ', placeholder: 'Descrizione' %>
</div>
</div>
and this is the error . I do not understand where the problem is
ActionController::ParameterMissing in Protocol::TrasmissionMeansController#create
param is missing or the value is empty: mean

Answer 1

The parameters are based on the class
def trasmission_mean_params
params.require(:mean).permit(:description)
end
Is looking for mean in the params hash but your class is called TransmissionMean which means it should be
def trasmission_mean_params
params.require(:transmission_mean).permit(:description)
end