Nullify duplicate slugs under the same parent after reodering pages.

[parndt]

Fixes #2070

[parndt]

Updated with drop(1) by the brilliant @gwagener

[parndt]

This could also be done using:

def nullify_duplicate_slugs_under_the_same_parent!
  table = Page.translation_class.arel_table
  Page.includes(:translations).group(:parent_id, table[:slug]).having(table[:slug].count.gt(1)).count(&:slug).each do |(parent_id, slug), count|
    Page.by_slug(slug).where(:parent_id => parent_id).drop(1).each do |page|
      page.slug = nil
      page.save
    end
  end
end

[parndt]

I'm afraid that we're also going to have problems with slugs in locales other than the current locale too >_>

[gwagener]

It could be done with an arel table and I assume the performance would be better because it's doing more of the filtering in the database. However, if the performance gain isn't noticeable I think the way it is is easier to read.

With the arel table do you need to pass count into the block?

[parndt]

OK I've dealt with the locale issues and force pushed. Good to go 👍

[ugisozols]

Thanks @gwagener for Array#drop - seems like a really handy method to know about.

[parndt]

I smell a blog post @ugisozols

[viglesias]

ERROR: column "refinery_pages.lft" must appear in the GROUP BY clause or be used in an aggregate functio
Correct could be:

def nullify_duplicate_slugs_under_the_same_parent!
    t_slug = translation_class.arel_table[:slug]
    joins(:translations).group(:locale, :parent_id, t_slug, :lft).having(t_slug.count.gt(1)).count.
        each do |(locale, parent_id, slug), count|
      by_slug(slug, :locale => locale).where(:parent_id => parent_id).drop(1).each do |page|
        page.slug = nil # kill the duplicate slug
        page.save # regenerate the slug
      end
    end
  end

[parndt]

@viglesias can you open a pull request with a failing test case if you're having issues please?