Weird behavior with DataModelSortComparer

Ok, found the problem myself, I also hae to return values depending of yCategoryModel.
So here's my final code :

public override int Compare(IDataModel x, IDataModel y)
{
 // Sort the "Basic" category before anything else and "To Test" after anything else
 if (x is ICategoryModel xCategoryModel && y is ICategoryModel yCategoryModel)
 {
  switch (xCategoryModel.Name)
  {
   case "Basic":
    return -1;
   case "To Test":
    return 1;
   default:
    switch (yCategoryModel.Name)
    {
     case "Basic":
      return 1;
     case "To Test":
      return -1;
     default:
      return 0;
    }
  }
 }
}

Hi Antoine,

When you make a sort comparer, you need to have it handle each item.  You are returning 0 (meaning equal) for a number of things so that will sort them in random orders.  Instead of returning zero for things you don't care about, return base.Compare(x, y).  That will keep order properlly and will prevent the randomness you see.

Also note that WPF sort comparers will sometimes pass things in x or y.  You can't really predict, so you need to handle both x and y scenarios.  Your code was originally only handling x but as you saw later you need to do both.  And also I think you originally had it backwards in that -1 should be for first, and 1 is for last and corrected that in the latter code.

Hi !

thanks for your feedback and your explanations ! I'll change this 0 stuff :)

And yes it was more intuitive for me to have the 1 at highest place and -1 lowest :) but still ok !