I have some parameters in URL that represents IDs. On this page, I am printing out a list of articles - usually between 50 and 70.
In the URL are IDs - say - in this format: website.com/mark/articles/10/12/13/20 (IDs of articles: 10, 12, 13, 20).
I would save these IDs into an array and while printing out all Mark's articles on the page, I would need to sort the articles the way that articles with IDs 10, 12, 13 and 20 would be on top of the list.
How to achieve something like this?
For a SQL solution, check mu's answer. Using Ruby:
articles = Article.where(id: ids).index_by(&:id).values_at(*ids) +
Article.where.not(id: ids)
Of course, a SQL solution is nicer if you need a Relation and not an Array.
There are two ways to do this. Plain ruby or SQL.
The plain ruby version is probably easier to understand and also not vulnerable to possible SQL injection:
article_ids_on_top = [10, 12, 13, 20]
articles = Article.all
top_articles = articles.select{|article| article_ids_on_top.include?(article.id) }
bottom_raticles = articles.reject{|article| article_ids_on_top.include?(article.id) }
@articles = top_articles + bottom_articles
SQL version:
article_ids_on_top = [10, 12, 13, 20]
@articles = Article.order("FIELD(id, [#{article_ids_on_top.join(',')})")
FIELD a MySQL-ism?[ ] incorrectly, if I use it without the brackets, the error is gone, but the data are not sorted properly.