Ruby on Rails Paperclip - Files not saving

I have it setup so that my user model has the attached file :photo:

has_attached_file :photo, :styles => { :small => "150x150>" },
              :url  => "../avatars/:basename.:extension",
              :path => ":rails_root/public/avatars/:basename.:extension"
validates_attachment_size :photo, :less_than => 5.megabytes
validates_attachment_content_type :photo, :content_type => ['image/jpeg', 'image/png']

To try and make use of this, I've added a field for avatar uploads in the user edit view:

<% form_for @user, :html => { :multipart => true } do |f| %>
#Unimportant Stuff here
<%= f.file_field :photo %>
#Unimportant Stuff here
<% end %>

And then created the edit and update methods in my user controller:

def edit
    @user = User.find(params[:id])
end

def update
    @user = User.find(params[:id])
    respond_to do |format|
     if @user.update_attributes(params[:user])
    format.html { redirect_to(@user, :notice => 'User was successfully updated.') }
    format.xml  { head :ok }
     else
    format.html { render :action => "edit" }
    format.xml  { render :xml => @user.errors, :status => :unprocessable_entity }
     end
    end
end

My issue is that with all of this, upload开发者_高级运维ing files still doesn't work. On visiting a users' page and uploading an image, I just get "Missing" where the image is supposed to be. If I set the image to a required field, I get an error stating that the filename is required (so I guess the uploading just isn't working correctly?).

Any help would be greatly appreciated.

---

Don't forget to create the folder structure where the attachments are supposed to be saved into.