Rails query and order with same array used for query

Question

I have method

def self.get_ayahs_by_array(ayahs_keys_array)
  self.where(ayah_key: ayahs_keys_array)
end

Which does a query on the Quran::Ayah model. ayahs_keys_array is an array of keys (primary_key) in a certain order. The query returns a different order, but I want it to return as the same order as the queried array.

Example: ayahs_keys_array is [5,4,1,2,7] and I want it to return in THAT order and not [1,2,4,5,7]

Any ideas?

Answer 1

In MySql:

self.where(ayah_key: ayahs_keys_array).order("FIELD(ayah_key, #{ ayahs_keys_array.joins(', ') })")

For postgres is slightly more complicated as you need to build whole CASE statement. Might be easier to do it on the application level:

self.where(ayah_key: ayahs_keys_array).order_by {|r| ayahs_keys_array.index r.ayah_key}

Finally, you can try this gem: https://github.com/panorama-ed/order_as_specified . If you do, please let us know how it went as I never used it.