Rails dropdown menu with required fields

Question

I am trying to tweak an existing profile setup menu so that I can predetermine certain fields, such as gender with drop down options rather than the user having to type them in. The code as it stands is as below,

<%= form_for @profile, html: {multipart: true}, url: profile_path do |f| %>

  <div class="col-md-6">

    <div class="form-group">
      <%= f.text_field :firstname, required: true, placeholder: 'Firstname', class: 'form-control' %>
    </div>


    <div class="form-group">
      <%= f.text_field :lastname, required: true, placeholder: 'Lastname', class: 'form-control' %>
    </div>

      <div class="form-group">
      <%= f.date_field :dob, required: true, placeholder: 'Date of Birth', class: 'form-control' %>
    </div>

    <div class="form-group">
      <%= f.text_field :contactnr, required: true, placeholder: 'Contact Number', class: 'form-control' %>
    </div>

    <div class="form-group">
      <%= f.text_field :address1, required: true, placeholder: 'Address Line 1', class: 'form-control' %>
    </div>

    <div class="form-group">
      <%= f.text_field :address2, required: true, placeholder: 'Address Line 2', class: 'form-control' %>
    </div>

    <div class="form-group">
      <%= f.text_field :town, required: true, placeholder: 'Town', class: 'form-control' %>
    </div>

    <div class="form-group">
      <%= f.text_field :county, required: true, placeholder: 'County', class: 'form-control' %>
    </div>

    <div class="form-group">
      <%= f.text_field :country, required: true, placeholder: 'Country', class: 'form-control' %>
    </div>

    <div class="form-group">
      <%= f.text_field :postcode, required: true, placeholder: 'Postcode', class: 'form-control' %>
    </div>

    <div class="form-group">
      <%= f.text_field :gender, required: true, placeholder: 'Gender', class: 'form-control' %>
    </div>

    <form action="">
      <input type="radio" name="sex" value="Male">Male<br>
      <input type="radio" name="sex" value="Memale">Female
    </form>

  </div>

  <div class="col-md-6">

    <div class='uploaded-pic'>
      <%= image_tag @profile.image.url(:medium) %>
    </div>

    <div class="form-group">
      <%= f.file_field :image %>
    </div>

    <%= f.submit class: 'btn btn-success' %> </p>

  </div>

<%end%>

Specifically, I want to create some kind of mix of the below two pieces of code, so that the user can select a value in the drop down that will then be saved when the form is submitted.

<div class="form-group">
          <%= f.text_field :gender, required: true, placeholder: 'Gender', class: 'form-control' %>
        </div>

        <form action="">
          <input type="radio" name="sex" value="Male">Male<br>
          <input type="radio" name="sex" value="Memale">Female
        </form>

Answer 1

You can use a select like this

<%= f.select :gender, %w{Male Female}, :prompt => 'Select', required: true, placeholder: 'Gender', class: 'form-control' %>

For More Info, see this API.