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Merging two IEnumerables in an elegant way

I have two IEnumerable variables, both can be null. I need to combine them into one list. Here's a straight forward 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 for smaller lines of code?

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2 answers


Just check for null and assign Enumerable.Empty

if it is null. This can be done in one step using the null coalescing operator ?? 



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

return ienumerable1.Union(ienumerable2);
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   var ienumerable1 = GetEnumerable1(); 
    var ienumerable2 = GetEnumerable2(); 
    return ienumerable1 != null
                    ? (ienumerable2 != null ? ienumerable1.Union(ienumerable2) : ienumerable1)
                    : ienumerable2;


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