undefined method update for nil class - ruby-on-rails

Question

After a user logs in, I'm trying to collect additional info to update in the data base
this is my controller
def show
#user = User.find(params[:id])
end
def new
#user = User.new
end
def additional_info
#user = User.find params[:id]
end
def update
if #user.update(user_addinfo)
redirect_to user_path(#user), notice: 'User was successfully updated.'
else
render action: 'additional_info'
end
end
def create
#user = User.new(user_params)
if #user.save
#session[:user_id] = #user.id
#UserMailer.welcome_email(#user).deliver
sign_in #user
redirect_to additional_info_path(#user)
flash[:success] = "Welcome to InYourShoes!"
else
render'new'
end
end
private
def user_params
params.require(:user).permit(:name, :email, :password, :password_confirmation)
end
def user_addinfo
params.require(:user).permit(:year)
end
end
the error occurs at the def update function if #user.update(user_addinfo), rails says its undefined.
def user_addinfo is a action method and def additional_info is the actual page
the view for the page:
<div class="row">
<div class="col-xs-12 col-sm-6 col-sm-offset-3">
<%= form_for(#user, :html => {:class => 'form-horizontal'}) do |f| %>
<fieldset>
<p>Do you have experience in Business? If yes, select one of the following:
<div class="input-group">
<div class="input-group-btn">
<button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown">Select one <span class="caret"></span></button>
<ul class="dropdown-menu">
<li>Entrepreneurship</li>
<li>Investments</li>
<li>Management</li>
<li class="divider"></li>
<li>All of the Above</li>
</ul>
</div><!-- /btn-group -->
<%= f.text_field :year , :class => "form-control", :placeholder => "Years of experience" %>
</div>
</p>
<div class = "center form-actions">
<%= f.submit "Submit", class: "btn btn-lg btn-primary" %>
</div>
</fieldset>
<% end %>
</div>
</div>
am i saving the #user in the wrong place? I'm still new to the concept of #variablename instance variable... help and explanation is greatly appreciated

Answer 1

It is because you did't initialize the #user in "update" method.
Usually you need to do something like you did in "show" method.
#user = User.find(params[:id])
You current code, #user in "update" method is nil because you didn't assign any value to it. And a "nil" variable don't have the method "update".

Answer 2

You probably shouldn't try to overload your update function to capture the functionality of both edit and update (which you are doing, the other answers overlooked this). But the reason #user is nil upon form submission is probably because of this line:
render action: 'additional_info'
I'm guessing that line isn't doing what you expect. Rather than run the addition_info action and rendering the form, I believe that is simply performing the render. You probably want to redirect_to 'additional_info' and add a route for it if needed. Then you can ensure that the form is submitting the #user object correctly back to the update function.

Answer 3

You have to fetch the user additional information before updating it
def update
#user = User.find(params[:id])
if #user.update_attributes(user_addinfo)
#your redirection
else
#your redirection
end
end

Answer 4

def update
self.additional_info
if #user.update(user_addinfo)
redirect_to user_path(#user), notice: 'User was successfully updated.'
else
render action: 'additional_info'
end
end
#user doesn't exist with update, you'll need to create it first, which you've kind of done already