Rails Helper for user picture

I currently have some dirty code in a partial and thought it'd be good to move it to a Helper but can't make it happen.

Here is what I have in my "user_picture" partial so far:

<% if defined?(user) %>
    <%- if user.picture_id == 0 -%> 
        <%= image_tag('/images/einstein.png', :size => size) -%>
    <%- else -%>
        <%= image_tag(user.picture.public_filename(:avatar), :size => size) %>
    <%- end -%>
<% else %>
    <%- if !logged_in_user || logged_in_user.picture_id == 0 -%> 
        <%= image_tag('/images/einstein.png', :size => size) -%>
    <%- else -%>
        <%= image_tag(logged_in_user.picture.public_开发者_开发知识库filename(:avatar), :size => size) %>
    <%- end -%>
<% end %>

How do I make it a helper?

Thanks!

---

remove your code to app/helpers/application_helper.rb

def my_helper(user, size)
  if defined?(user)
    if user.picture_id == 0
      image_tag('/images/einstein.png', :size => size)
    else
      image_tag(user.picture.public_filename(:avatar), :size => size)
    end
  else
    if !logged_in_user || logged_in_user.picture_id == 0
      image_tag('/images/einstein.png', :size => size)
    else
      image_tag(logged_in_user.picture.public_filename(:avatar), :size => size) %>
    end
  end
end

and then call from your views: my_helper(current_user, size)

---

Off the top of my head, the helper could be:

def picture_for(user) #If you need to, pass size as a parameter or..
  if user.nil? or user.picture.nil?
    image_tag('/images/einstein.png', :size => size) # ..you need to define size somewhere in this helper
  else
    image_tag user.picture.public_filename(:avatar), :size => size
  end
end

And you could do something like this in the partial:

if defined?(user)
  picture_for(user)
elsif logged_in_user
  picture_for(logged_in_user)
else
  picture_for(nil)
end

---

I'm assuming you know the size in advance, but you could easily pass that into the helper as well.

def user_picture_tag(user)
  return image_tag(user.picture.public_filename(:avatar), :size => "50x50") if user.present? && user.picture_id != 0
  image_tag('/images/einstein.png', :size => "50x50")
end

Use it like this: (its ok if logged_in_user is nil)

user_picture_tag(logged_in_user)
# OR
user_picture_tag(@user)