getting going

Hi, I'm just getting going with RoR and thus far am enjoying it very much. There's just something oddly satisfying about it. That being said I do find myself tripping over the little things...like NIL.

I've been doing a tutorial on building a flickr tag search and noticed that it doesn't handle NIL results well; actually, it doesn't handle errors at all.

My controller contains this: (it renders a partial with a collection of images from flickr) The partial is just an image tag: ("<img class="photo" src="<%= photo.sizes[0]['source'] %>">")

render(:partial => "photo", :collection => flickr.photos(:tags => params[:tags], :per_page => '28')) unless :collection.nil?

Which I'm assuming is completely wrong since I still get this:

You have a nil object when you didn't expect it! You might have expected an instance of Array. The error occured while evaluating nil.collect

When entering a tag like "peachqwwerwer" as a search term.

My question is this. If you know that there's a good likelihood that you're going to get back NIL records then what and where is the best (most effective/flexible) place to handle it and what is the general best practice for error handling like this?

I'd like to show the user a nice looking message "Golly, there's nothing out there that matches "peachwwerwer"." (etc)

Many thanks in advance.

B/

Well, I tried this, it seems like a sensible strategy and all but it doesn't allow me to intercept NIL results in the collection.

class FlickrController < ApplicationController   def search     flickr = Flickr.new 'fcaadf470f78d2f8bd8098a1411fb687'     @photos = flickr.photos(:tags => params[:tags],:per_page => '28')      if flickr.photos.size < 1       flash[:notice] = "Golly, nothing that matched" + params[:tags] + "."      else       render(:partial => "photo",:collection => @photos)      end   end end

searching for "peach2323" (tags) results in:

NoMethodError in FlickrController#search

You have a nil object when you didn't expect it! You might have expected an instance of Array. The error occured while evaluating nil.collect

When what one might expect a nice polite message flashed to screen as per the controller.

I'll keep trying...the answer is out there somewhere. It seems somehow to hinge on 'nil.collect'.

B/

Interesting but confounding behavior here...

flash[:notice] = @photos.nil? search for tags 'platinotype' which at present returns 8 results and @photos.nil? equals 'false'; meaning it is NOT nil, which is what one would expect.

However...

change 'platinotype' to 'platinotype1212'; which should return NIL meaning that @photos.nil? equals 'true' and I'm right back where I started...

"You have a nil object when you didn't expect it! You might have expected an instance of Array. The error occured while evaluating nil.collect"

I'd expected that the @photos.nil? would return 'false' if the collection was populated and 'true' if empty, but this seems not to be the case. How on earth is one supposed to handle conditional statement based on a simple boolean if only half the data is there?

Or am I missing some simple and vital information on handling collections in RoR?

B/

Yep, I tried this. It looks like it should work and work well. But I still get:

NoMethodError in FlickrController#search

You have a nil object when you didn't expect it! You might have expected an instance of Array. The error occured while evaluating nil.collect

If I search for 'platinotype' I get 8 results and it all works. If I search for 'platinotype123123' (which I know won't return results) I get the above error and no matter how I try to get the length or content of the array I can't get past the nil.collect error as above.

I'm wondering if it has to do with the flickr.rb (gem) and it not handling back nil (empty) arrays? (Does my being on windows affect this at all? There seem to be more recent gems for non-windows platforms.)

Thanks for the help! I'll keep reading in search of the answer.

b/

bjorn wrote:

I'm wondering if it has to do with the flickr.rb (gem) and it not handling back nil (empty) arrays? (Does my being on windows affect this at all? There seem to be more recent gems for non-windows platforms.)

Thanks for the help! I'll keep reading in search of the answer.

b/

…three years later, I'm still running into this problem, and I have the same suspicion: there's an internal error in the flickr gem when the search turns up nothing.

By now, you must have given up on the gem or found a better solution. for flickr with RoR. I'll continue searching for a solution to this problem for now.

Actually, I was able to fix it by modifying the flickr.rb file from the gem at line 109. replaced it with the following:

    if collection        collection.collect { |photo| Photo.new(photo['id'], @api_key) }      else        return nil      end