Ordering categories using SQL

The following code changes the order of categories to be alphanumeric using SQL.

Preconditions.
Postgres backend

UPDATE categories
SET POSITION = subquery.position
FROM (
	SELECT POSITION
	, CASE WHEN category_id = 0 THEN parent_category_id ELSE category_id END category_id 
	, CASE WHEN category_id = 0 THEN parent_category_name ELSE category_name END category_name 
	FROM (
		SELECT ROW_NUMBER - 1 AS POSITION
		, parent_category_id
		, parent_category_name
		, category_id
		, category_name
		FROM ( SELECT row_number() OVER ( ORDER BY parent_category_name, category_name )
		, * FROM (
		SELECT * FROM (
			SELECT id parent_category_id
			, name parent_category_name 
			, 0 category_id
			, cast('' AS text) category_name
			FROM categories 
			WHERE parent_category_id IS NULL ORDER BY name
		) parent_categories
		UNION 
		(
			SELECT child.parent_category_id
			, parent.name parent_category_name 
			, child.id category_id
			, child.name category_name
			FROM categories child
			INNER JOIN categories parent
			ON child.parent_category_id = parent.id
			WHERE child.parent_category_id IS NOT NULL ORDER BY child.name
		) 
		) parents_with_children
		ORDER BY parent_category_name, category_name
		) ordered_parents_with_children
		ORDER BY ROW_NUMBER
	) category_positions_sorted_alphabetically
) subquery
WHERE id = subquery.category_id ;

I ran the code by starting up a psql session.

/var/discourse/launcher enter app
su postgres
psql discourse

and then executing the SQL.

Running from rails console.

ActiveRecord::Base.connection.execute("UPDATE categories SET POSITION = subquery.position FROM ( SELECT POSITION , CASE WHEN category_id = 0 THEN parent_category_id ELSE category_id END category_id , CASE WHEN category_id = 0 THEN parent_category_name ELSE category_name END category_name FROM ( SELECT ROW_NUMBER - 1 AS POSITION , parent_category_id , parent_category_name , category_id , category_name FROM ( SELECT row_number() OVER ( ORDER BY parent_category_name, category_name ) , * FROM ( SELECT * FROM ( SELECT id parent_category_id , name parent_category_name , 0 category_id , cast('' AS text) category_name FROM categories WHERE parent_category_id IS NULL ORDER BY name ) parent_categories UNION ( SELECT child.parent_category_id , parent.name parent_category_name , child.id category_id , child.name category_name FROM categories child INNER JOIN categories parent ON child.parent_category_id = parent.id WHERE child.parent_category_id IS NOT NULL ORDER BY child.name ) ) parents_with_children ORDER BY parent_category_name, category_name ) ordered_parents_with_children ORDER BY ROW_NUMBER ) category_positions_sorted_alphabetically ) subquery WHERE id = subquery.category_id")
1 Like

I’ve not tested this recently but here’s at least a hint for how to alpha-sort categories at the rails console:

# alpha sort all categories matching search and their sub-categories

  def sort_matching_categories_and_subcategories(search)
    categories = Category.where("name like ?", search)
    position = 100
    categories.order(:name).each do |cat|
      position += 5
      cat.position = position
      cat.save!()
      c_position = 0
      children = Category.where(:parent_category_id=>cat.id)
      children.order(:name).each do |c|
        c_position += 5
        c.position = c_position
        c.save!()
      end
    end
  end


 # alpha sort subcategories of a single category matching search
def sort_matching_subcategories(search)
  categories = Category.where("name like ?", search)
  if categories.count > 1
    puts "Found more than one category"
  end
  categories.order(:name).each do |cat|
    c_position = 5
    children = Category.where(:parent_category_id=>cat.id)
    children.order(:name).each do |c|
      c_position += 5
      c.position = c_position
      c.save!()
    end
  end
end
1 Like

Thanks @pfaffman

Based on your ruby code I came up with

def sort_categories_by_name(skip=0)
  
  parents = Category.where("parent_category_id is null")
  position = 0
  parents.order(:name).each do |parent|
    parent.position = position
    parent.save!()
    position += (1+skip)
    children = Category.where(:parent_category_id=>parent.id)
    children.order(:name).each do |child|
      child.position = position
      child.save!()
      position += (1+skip)  
    end
  end
  
  position += -(1+skip)  
  return position
  
end

sort_categories_by_name
1 Like

Hi. First time here.
Does this post clarify that Categories cannot be set alphabetically via some GUI option?

Thanks

Sort of. There are settings to put them in a fixed order. I think you first set a system setting (search for fixed, perhaps) and then you can do it in the ux.

If you have a dozen, it’s not too bad to do it in the ux (that interface has been troublesome and I don’t know how it works these days, so some of this might be wrong), if you have hundreds and won’t change, I once wrote some stuff to run at the console to sort them. If you have lots and change them all the time and want to keep them sorted, you’d need a plugin.

Thanks. I’m only a user of the ‘discourse’ Freephone forum and asked the moderators if they could change the listed order, but the initial response was to query this forum to find out how, so clearly not a readily available option I imagine.

Thanks again

Unless there are dozens of categories, it’s just not a big deal. And if they sent you here rather than looking in the settings themselves or asking here themselves, they just don’t want to do it.

Thanks again.

I think the moderators don’t have access to the backend, which seems essential.

I think I’ll download and host one then I should be able to find out how to do what I want and pass on the info :slight_smile: There must be an administrator that can handle the issue.

1 Like

Looks like one of the moderators knows how to do it, will let you know. The word is it can be done via the hamburger menu ??