ajax-datatables-rails: Problem with custom_columns and search

I have a problem regarding the searchable functionality of one of my datatables because I added a couple of custom columns in my query (both sum calculations).

First, I had to override the method as_json in the way described here: #159 in order to display the table properly (count and number of rows), but now I’m unable to perform any search.

My first attempt was to override using a custom filter method following this example, I added this code:

def filter_custom_column_condition
  ->(column) { ::Arel::Nodes::SqlLiteral.new(column.field.to_s).matches("#{ column.search.value }%") }
end

without luck, both columns are Numeric, I also tried using the cond: :eq as suggested in docs but another error appears.

Checking logs I realized that it looks like the query doesn’t consider the custom columns because the name (an alias) is not present. To give an example I put on the search box the number “85” in order to show the generated sql:

SELECT COUNT(*) FROM (SELECT ro_eventos_perdidas.id, ro_eventos_perdidas.fecha_ocurrencia,  
                 ro_eventos_perdidas.descripcion, ro_eventos_perdidas.recuperable, ro_eventos_perdidas.monto_perdida, 
                 coalesce(sum(monto_recuperado),0) as monto_recuperado,
                 coalesce(ro_eventos_perdidas.monto_perdida - coalesce(sum(monto_recuperado),0),0) as monto_pendiente FROM "ro_eventos_perdidas" left outer join ro_recuperaciones_eventos recup on 
                                 recup.ro_evento_perdida_id = ro_eventos_perdidas.id WHERE (ro_eventos_perdidas.monto_perdida > 0 and ro_eventos_perdidas.recuperable = true 
                  and ro_eventos_perdidas.duplicado = false ) AND ((((((CAST("ro_eventos_perdidas"."id" AS VARCHAR) ILIKE '%85%' OR CAST("ro_eventos_perdidas"."fecha_ocurrencia" AS VARCHAR) ILIKE '%85%') OR CAST("ro_eventos_perdidas"."descripcion" AS VARCHAR) ILIKE '%85%') OR CAST("ro_eventos_perdidas"."recuperable" AS VARCHAR) ILIKE '%85%') OR CAST("ro_eventos_perdidas"."monto_perdida" AS VARCHAR) ILIKE '%85%') OR 85 ILIKE '85%') OR 85 ILIKE '85%') GROUP BY ro_eventos_perdidas.id) AS foo

as you can see at the end of this query, it shows OR 85 ILIKE '85%' which is wrong, it should be OR CAST("ro_eventos_perdidas"."monto_recuperado" AS VARCHAR) ILIKE '%85%')… which is one of my custom columns.

I’m not sure if I have to add something else or maybe something is missing, so please point me in the right direction.

Regards.

Stack:

Postgresql 9.4 Rails 4.2.7 jquery-datatables-rails 3.3.0 ajax-datatables-rails 0.4.0