Merge two IEnumerables in elegant way [closed]

Question

I have two IEnumerable variables, both can be null. I need to merge them into a single list. Here is direct approach.

var ienumerable1 = GetEnumerable1(); 
var ienumerable2 = GetEnumerable2(); 

if(ienumerable1 != null){
   if(ienumerable2 != null){
      return ienumerable1.Union(ienumerable2);
   }
   return ienumerable1;
}
else{
   return ienumerable2;
}

Is there a more elegant way in less lines of code to do this?

Answer 1

Just check for null and assign Enumerable.Empty if it is null. This can be done in one step with the null coalescing operator ??

var ienumerable1 = GetEnumerable1() ?? Enumerable.Empty<WhateverType>();
var ienumerable2 = GetEnumerable2() ?? Enumerable.Empty<WhateverType>(); 

return ienumerable1.Union(ienumerable2);