Extra instance variable in controller is nil in view?

Question

I have been searching through Stack Overflow for a few hours now, but none of the related questions seem to apply to my issue.

I am new to Rails, with this being my first real project, and I may be confusing the MVC setup a little. I am attempting to assign the @stars instance variable while in an action of the searches_controller.rb:

def create
  @search = Search.new(params[:search])
  tempstr = searchstr(@search)
  @stars = Star.where("tempstr", :limit => 100)
end

@search is created fine, being a complex search with varying parameters. tempstr is just a simple string container for the results of searchstr(@search), which is a quick method for converting the search parameters into a MySql-relevant string (which seems to be easier than trying to use the .where helper normally, in this case). I'm sure I can just put searchstr(@search) directly into the .where, but I split them up for now so I can inspect the elements as they pass through.

Anyways, the issue comes up when I try to call @stars in the show.html.erb view. Even with something as simple as this:

<% @stars.each do |star| %>
  <%= display stuff %>
<% end %>

I get an error saying 'each' is not a method of nil:NilClass. So, I changed it to the following to see if @stars was nil:

<%= @stars.inspect %>

Sure enough, @stars is nil. However, when I add this line to my controller to check @stars there:

return render @stars.each

I see that the variable is filled with the correct star objects from the Star.where(), just as I had intended. A quick .inspect shows the variable is not nil, when in the controller.

So, I am unsure why the view is receiving it as nil if it has been defined in the controller just fine. I wouldn't be surprised if it was me misunderstanding how MVC works, though. The Star class was defined in the Star model, but maybe it is because I am trying to access it from the Searches controller, and thus it isn't initialized for the view?

Should I be going about doing this some other way? I attempted to use a local variable (using stars instead of @stars), but then the view says "Undefined local variable or method 'stars'".

Any help would be much appreciated, I have already wracked my brain for hours creating the complex search and parsing the star file data into the database, so I'm a bit burnt out. I can supply more information if requested, I'm not sure what else would be helpful in providing an answer.

Well, you certainly don't want <%= @stars.each %>; is that a typo? Also, "#{tempstr}" when tempstr is already a string is a little redundant. If you log or pry in the controller does @stars really contain values? — Dave Newton
– Dave Newton, Commented Apr 10, 2012 at 22:53
@Dave Newton - For one, thanks for catching tempstr; I had originally meant to do the .where with rails syntax, which would have needed the evaluation. For 2, the = in there was a typo, and I'll fix that in the question, thanks again. For 3, using the logger.debug to output @stars.each do |star| star.ra end (where star.ra is one of the star variables) seems to have logged the entire contents of @stars, which include all the variables of 2 stars that the .where is supposed to find. I think that means it does contain values, though it could be getting it from somewhere else, I suppose? — Xadera
– Xadera, Commented Apr 10, 2012 at 23:45

Mischa · Accepted Answer · 2012-04-11 04:34:26Z

3

You are setting @stars in the create method, but the view you are talking about is show.html.erb. Try setting @stars in the show method too. Something like this:

def show
  @search = Search.find(params[:id])
  tempstr = searchstr(@search)
  @stars = Star.where("tempstr", :limit => 100)
end

If this does not help you, please show the rest of you controller actions, so we can help you better.

answered Apr 11, 2012 at 4:34

Mischa

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2 Comments

Xadera Over a year ago

Yes, you were absolutely correct! I had just figured it out myself not long before you posted, but thanks very much for answering and confirming! I had originally thought the Show page automatically used the Create method when initializing from there, but I was wrong. Such a simple mistake made me spend hours cooking my brain.

kubbing Over a year ago

you answer helped me solve totally not related rails issue. you deserve uptove :D

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