<%# If this guy is logged in AND not in the tournament %>
<% if signed_in? && !t.players.include?(current_user) %>
<%= form_tag(tournament_path(t), method: "put") do %>
<%= submit_tag("Join") %>
<% end %>
<% else %>
You've signed up for this tournament!
<% end %>
<% end %>
<% else %>
No tournaments going on right now... Why not start your own?