Best way/pattern to build request based on different service

Question

I have a about 20 different services which I have to send requests to which require a slightly different set of headers.

The bad legacy code is something like this,

row = db.query_for_service()

if row.type == 'foo1'
   // add common headers to request
   // add foo1 specific headers 1
   // add foo1 specific header 2
   // add foo1 specific header 3
else if row.type == 'foo2'
   // add common headers to request
   // add foo2 specific header 1
...
...
...
else if row.type == foo20
   // add common headers to request
   // add foo20 specific header 1
   // add foo20 specific header 2 
   // ...

send_request()

What is the best way to refactor this? I have considered some patterns that may work here (strategy, builder) but I am not too sure.

I am currently learning both Java and Python and I would to get thoughts on how the solutions would differ in the two languages

Answer 1

Personally, what I would do is something along these lines.

#Put this in the initialisation 
Map foos<row.type,String> = new Map<row.type, String>()
#Populate the map 
map.set('a') = 'headerA specific params x=1'
map.set('b') = 'headerB specific params x=2'
map.set('c') = 'headerC specific params y=3'
map.set ...

Map bars<String,String> = new Map<String,String()
bars.set('fooA') = 'a,b'
bars.set('fooB') = 'a,c'
String commonheader = "HTTP/1.1"


#This would be in a method    
row = db.query_for_service()
String output_header += commonheader
for i in bars.get(fooN).split(','):
    output_header += foos.get(i)
send_request()

In sort of pseudo java/python. The map would be pre-filled with everything you need, then just pick out what you want and attach.