Ruby on Rails

>> The tutorials are then displayed in order of there id (auto-
>> incrementing) in their categories show method.
>> The thing is, I want to create a link that goes from one tutorial
>> (with an id of 10 for example) to the next tutorial in that category
>> (which might not have an id of 11, as I create different tutorials at
>> different times, therefore creating different ids for two tutorials
>> seemingly next to eachother in order).
>>
>> Obviously I know I will need something like this:
>> <%= link_to 'Next lesson....', %>
>>
>> but I just don't know how I can manage it..
>>
>> By the way, every tutorial has a: category_id to determain which
>> category they are in (this is an integer).
>>
>
> If I were you, i'd create a position column on tutorials, which
> determines the ordering of tutorials for a category (ordering by id
> might seem the simplest but stops you from ever reordering tutorials.
> Given a tutorial, the next one is the first one in the same category
> whose position is greater than the current ones (you could write a
> next_tutorial method on tutorial). There's a plugin called
> acts_as_list that you might find helpful maintaining the position
> column. If you're hell bent on ordering by id then it's as if id is
> your position column
>
> Fred

I agree with Fred as it allows you to easily re-order the tutorials if
you want to, but if you don't... then...

next_tutorial = Tutorial.find(:conditions => ["id > ? AND category_id
= ?", current_tutorial_id, current_category_id], :order =>
'id', :limit => 1)

prev_tutorial = Tutorial.find(:conditions => ["id < ? AND category_id
= ?", current_tutorial_id, current_category_id], :order => 'id
DESC', :limit => 1)

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