LINQ Conditional Group

Is it possible to write a LINQ statement with a conditional group clause? Here is basically what I'm trying to do:

bool someFlag = false;

var result = from t in tableName
   group t by new { (someFlag ? 0 : t.FieldA), t.FieldB } into g
   select g;

So basically if someFlag is set to true, I want to group only by FieldB, but if it's false I want to group by FieldA and FieldB.

From stackoverflow

• Co-worker figured it out for me:

  bool someFlag = false;
  var result = from t in tableName
     group t by new { FieldA = (someFlag ? 0 : t.FieldA), t.FieldB } into g
     select g;
  

  Bryan Watts : You can leave off everything after the "}". You don't explicitly have to select grouped items.

• In the case that your someFlag is not a variable dependent on the current element of the iterator, then I think you could make your code more readable by writing the following.

  bool someFlag = false;
  var result = someFlag ?
       (from t in tableName group t by t.FieldA into g select g) :
       (from t in tableName group t by t.FieldB into g select g);
  

  Admittedly it's slightly longer, but its purpose is significantly more obvious in my opinion.

  And to slightly simplify the code you just posted:

  bool someFlag = false;
  var result = from t in tableName
     group t by (someFlag ? t.FieldA : t.FieldB) into g
     select g;
  

  ...or am I missing something here?