Supply information automatically to simple form - ruby-on-rails

Question

I'm working on a simple little Rails social network and right now I am trying to automatically fill in the name of the currently signed in user when creating a new status update. My original code let them select their user name from a drop down which is silly - when you go on Facebook, you fill out the box and it automatically knows that it belongs to you. Here is my original code:
<%= simple_form_for(#status, html: {:class => "form-horizontal"}) do |f| %>
<% if #status.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#status.errors.count, "error") %> prohibited this status from being saved:</h2>
<ul>
<% #status.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<%= f.input :user_id, collection: User.all, label_method: :full_name %>
<%= f.input :content %>
<div class="form-actions">
<%= f.button :submit %>
</div>
<% end %>
And here is what I am trying to replace it with:
<%= simple_form_for(#status, html: {:class => "form-horizontal"}) do |f| %>
<% if #status.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#status.errors.count, "error") %> prohibited this status from being saved:</h2>
<ul>
<% #status.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<%= f.input :user_id, current_user.full_name %>
<%= f.input :content %>
<div class="form-actions">
<%= f.button :submit %>
</div>
<% end %>
It doesn't like this and says "can't convert Symbol into Integer"
How can I supply it with the logged in user's full name without ever giving them the option to chose another user?

Answer 1

user_id is the forreign key to User, it holds something like current_user.id not it's name.
It seems, that the user is already signed in, so you just need to show the name and provide the id to the create action:
<%= f.input :user_id, as: :hidden %>
<%= current_user.name %> <%# just for information %>
and set it in the new #status in the controller:
def new
#status = Status.new(user: current_user)
...
end

Answer 2

Your first input of the form is specified as an input for the :user_id which is an integer in your table of users. Putting a full name there is creating a mismatch in data types. Does this help?
Now that you want the username to be displayed without the user being able to change what is displayed, is there really a need to have this as an input? Can you just display the username in a normal <div></div>, so to speak?