Filter messages by multiple values from the message itself.

Recently a customer asked what would be right way to filter messages if he needs to filter them by combination of multiple values taken from different Fields across given message Segments.

So I expanded a little our well know example from page http://help.interfaceware.com/kb/filter-out-messages.

Here, we will use Lua lists and other handy things to make the code reasonably maintainable and easily scalable to any number of values to compare.

local Filter_1 = {'a','b','MESA_ADT','c'}
local Filter_2 = {'XYZ_ADMITTING','d','e','f'}

function main(myData)  
   local In = hl7.parse{vmd = 'matchAll.vmd', data = myData }
   local L = {
      MakeLookup(Filter_1),
      MakeLookup(Filter_2)
   }
   local P = {
      In.MSH[3][1]:nodeValue(),
      In.MSH[4][1]:nodeValue()
   }   
   local function push_valid()  
      local push = {}      
      for i =1,#L do
         push[i] = false
         if L[i](P[i]) then
            push[i] = true   
         end
      end
      
      if not MakeLookup(push)(false) then 
         return true 
      end
   end  
   if push_valid() then 
      queue.push{data=myData} 
   end
end

function MakeLookup(T)
   local L = {}
   for i=1, #T do
      L[T[i]] = true
   end
   return function(V) return L[(V)] end
end

The above code assumes two values to filter by.

If you need to filter by 3 values, then add in three places:
– add line local Filter_3 = {}
– add MakeLookup(Filter_3) declaration to list ‘L’
– add to list ‘P’ source Segment/Field to take the 3rd value from, e.g. In.MSH[4][1]:nodeValue()

That’s it.

Translator project for impatient is attached below.
Have fun and feel free to modify as you please, this is only example.

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