LINQ Conditional Group

Question

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.

Answer 1

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;

Answer 2

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?