set input value from url text

Question

I have a string passed in url so I want to retrieve a text from this url for example https://www.mywebsite.com/path/text_to_retrive and put in input

This is my code :

<%

%>

<% valid_access_code = @room.access_code.nil? || @room.access_code.empty? || @room.access_code == session[:access_code] %>
<%= render 'rooms/components/room_event', render_recordings: valid_access_code do %>
<% if room_authentication_required %>
<h2><%= t("administrator.site_settings.authentication.user-info") %></h2>
<% elsif !valid_access_code %>
<%= form_for :room, url: login_room_path(@room.uid) do |f| %>
  <div class="input-group join-input">
    <%= f.text_field :access_code,
          required: true,
          class: "form-control join-form",
          placeholder: t("room.enter_the_access_code"),
          value: "" ,
          autofocus: true %>
    <%= f.submit t("room.login"), class: "btn btn-primary btn-sm col-sm-3 form-control join-form" %>
  </div>
<% end %>
<% else %>
<%= form_for room_path(@room), method: :post do |f| %>
  <div class="input-group">
    <%= f.hidden_field(:search, :value => params[:search])%>
    <%= f.hidden_field(:column, :value => params[:column])%>
    <%= f.hidden_field(:direction, :value => params[:direction])%>
    <%= f.text_field :join_name,
        required: true,
        class: "form-control join-form",
        placeholder: t("enter_your_name"),
        value: "#{@name}",    ===> **here i want to put (text_to_retrive)**
        readonly: !current_user.nil?, 
        autofocus: true
        %>
    <span class="input-group-append">
      <button type="submit" class="btn btn-primary btn-sm px-7 form-control join-form">
        <%= (!@room_running && @anyone_can_start) ? t("room.start") : t("room.join") %>
      </button>
    </span>
  </div>
<% end %>

how can I make this thank you!