Redmine-Jobs/app/views/jobs/_form.html.erb

<%= form_with model: @job, url: form_target, id: "job_form" do |f| %>
  <%= error_messages_for @job %>
  <div class="box tabular">
    <p>
    <%= f.label :name %>
    <%= f.text_field :name %>

    <p>
    <%= f.label :description %>
    <%= f.text_area :description %>

    <p>
    <%= f.label :category %>
    <%= f.collection_select :category_id, JobCategory.all, :id, :name %>

    <p>
    <%= f.label :starts_on %>
    <%= f.date_field :starts_on %>

    <p>
    <%= f.label :ends_on %>
    <%= f.date_field :ends_on %>

    <%= f.hidden_field :project_id, value: @job.project.id %>

    <fieldset>
      <legend>Budget</legend>
      <%= f.fields_for :time_budgets do |ff| %>
        <p>
        <%= ff.label :hours, ff.object.category&.name || "Unassigned" %>
        <%= ff.number_field :hours %>
        <%= ff.hidden_field :category_id %>
        <%= ff.hidden_field :job_id %>
        <%= ff.hidden_field :_destroy, value: false %>
      <% end %>
    </fieldset>

  </div>
  <%= f.submit %>
<% end %>