`present` predicate doesn't seem to work as defined in the documentation

[dvkch]

Hi there,

I am trying to add a simple filter on a string column to an ActiveAdmin page. I already have the standard "contains/equals/etc" filter defined as filter :dsp_isrc, I am currently trying to add filter :dsp_isrc_present, as: :boolean, but this doesn't work as expected :

• when choosing "Yes", it doesn't return anything, although i do have Artists where this attribute is filled
• when choosing "No", it returns the proper list of Artists.

I think I was able to reduce the problem to this discrepancy :

my-project(dev)> Artist.ransack(dsp_isrc_present: '1').result.to_sql
=> "SELECT \"artists\".* FROM \"artists\" WHERE (\"artists\".\"dsp_isrc\" IS NOT NULL AND \"artists\".\"dsp_isrc\" != NULL)"

my-project(dev)> Artist.ransack(stripe_customer_id_present: '1').result.to_sql
=> "SELECT \"artists\".* FROM \"artists\" WHERE (\"artists\".\"stripe_customer_id\" IS NOT NULL AND \"artists\".\"stripe_customer_id\" != '')"

Suprisingly, one case ends up with a != NULL and the other with != '', the latter being correct according to the documentation.

I think the != NULL would explain why my list ends up empty when choosing "yes" in ActiveAdmin, since NULL equality always surprises me.

Both columns are defined identically in my schema, although they do have different indexes.

  create_table "artists", force: :cascade do |t|
    ...
    t.string "stripe_customer_id"
    t.string "dsp_isrc"
    t.index ["dsp_isrc"], name: "index_artists_on_dsp_isrc", unique: true, where: "(dsp_isrc IS NOT NULL)"
  end

I'd be very interested in understanding how i could fix this issue. Thanks in advance!

[dvkch]

I have tried following the custom predicates guide to build my own and hopefully workaround this issue, but arrive at the same exact problem:

# initializers/ransack.rb

module Arel
  module Predications
    def is_present(arg)
      bool = ActiveModel::Type::Boolean.new.cast(arg)
      if bool
        not_eq(nil).and(not_eq(''))
      else
        eq(nil).or(eq(''))
      end
    end
  end
end

Ransack.configure do |config|
  config.add_predicate 'is_present', arel_predicate: 'is_present'
end

# irb
my-project(dev)> Artist.ransack(dsp_isrc_is_present: '1').result.to_sql
=> "SELECT \"artists\".* FROM \"artists\" WHERE \"artists\".\"dsp_isrc\" IS NOT NULL AND \"artists\".\"dsp_isrc\" != NULL"