parser-to-query.rb

parser-to-db-query.rb

class Parser
  def self.run
   dataset = DB[Sequel[payload[:TenantID].to_sym][payload[:Entity].to_sym]]
  
   dataset = dataset.order(Sequel.send(payload[:sortDirection].to_sym, payload[:sortBy].to_sym) ) if payload[:sortBy].present?
  
   dataset = dataset.limit(payload[:PageSize]) if payload[:PageSize].present?
  
   offset = payload[:PageSize] * (payload[:Page] - 1)
   offset = 0 if offset < 0
   dataset = dataset.offset(offset) if payload[:Page].present?


   payload[:displayColumns].each do |displayColumn|
     if displayColumn.include?(".")
       fields = displayColumn.split(".")
       table_name = fields[0]
       field_name = fields[1]
       dataset = dataset.left_join(Sequel[payload[:TenantID].to_sym][table_name.to_sym], "#{payload[:Entity]}_id".to_sym => :id)
     end
   end


   dataset = dataset.select(*payload[:displayColumns].map {|displayColumn| displayColumn.include?(".") ? Sequel[displayColumn.split(".").first.to_sym][displayColumn.split(".").last.to_sym] : displayColumn.to_sym})


   sequel_object = build_filter( payload[:filter])
   dataset = dataset.where{Sequel.&(*sequel_object)}


   puts dataset.sql
   dataset.all
 end


 def self.build_filter(filters)
   buffers = []
   puts "before loop"
   puts filters.inspect
   filters.each do |filter|
     case
     when filter[:or].present?
       buffers.append(Sequel.|(*build_filter(filter[:or])))
     when filter[:and].present?
       buffers.append(Sequel.&(*build_filter(filter[:and])))
     else
       # debugger
       key = filter[:column]
       value = filter[:operands]
       case filter[:operator].to_s
       when 'equal'
         buffers.append({key.to_sym => value})
       when 'start_with'
         buffers.append(Sequel.ilike(key.to_sym, "#{value}%"))
       end
     end
   end
   buffers
 end


 def self.payload
   {
     "TenantID": "michat",
     "Entity": "employee",
     "displayColumns": [
         "name",
         "email",
         "submission.submission_type",
         "attendance.attendance_type"
     ],
     "filter":
     [
       {
             "column": "name",
             "operator": "start_with",
             "operands": "isnan"


       },
       {
         "or": [
           {
             "column": "name",
             "operator": "equal",
             "operands": [
                 "isnan"
             ]


           },
           {
             "column": "name",
             "operator": "start_with",
             "operands":  "alvin"
           }
         ]
       }
     ],
     "PageSize": 10,
     "Page": 1,
     "sortBy": "name",
     "sortDirection": "asc"
   }
 end
end