CODEWITHSUNDEEP
c#asp.netsorting
Kevin
Kevin

Reputation: 1019

Custom c# collection class sorting by multiple properties

I am sorting a custom class as follows, which is sorted by FirstHalfPoints:

 var firstHalfTables = new FirstHalfTableCollection();
        firstHalfTables.PopulateForSeason(SeasonId);
        firstHalfTables.Sort((t1, t2) => t1.FirstHalfPoints.CompareTo(t2.FirstHalfPoints));
        firstHalfTables.Reverse();
        FirstHalfTableRepeater.DataSource = firstHalfTables;
        FirstHalfTableRepeater.DataBind();

I also need to sort by a two further fields 'GD' - Goal Difference and 'GF' - Goals For- after this initial sort by 'FirstHalfPoints'

So the finished collection will be sorted by FirstHalfPoints, then by GD, then by GF.

Can anyone help me out with multiple sorting?

Upvotes: 0

Views: 512

Answers (2)

Random Dev
Random Dev

Reputation: 52270

you can use direct LINQ expressions: "OrderBy" and "ThenBy" too: MSDN Sorting Data

OR

you have to extent your comparison. You have to remember: a.CompareTo(b) should return -1 if a is "smaller" than b, 0 if they are equal and +1 if a is "bigger" than b. So try the following:

private void Compare(YourRow a, YourRow b)
{
   let v = a.FirstHalfPoints.CompareTo(b.FirstHalfPoints);
   if (v != 0) return v;

   v = a.GD.CompareTo(b.GD);
   if (v != 0) return v;

   return a.GF.CompareTo(b.GF);
}

and call Sort with this function.

Upvotes: 1

svick
svick

Reputation: 244757

You could use LINQ, which often makes the code more readable:

var firstHalfTables = new FirstHalfTableCollection();
firstHalfTables.PopulateForSeason(SeasonId);
var firstHalfTablesProcessed = (from table in firstHalfTables
                                orderby table.FirstHalfPoints, table.GD, table.GF
                                select table).Reverse()
FirstHalfTableRepeater.DataSource = firstHalfTablesProcessed;

Or you could make your comparison delegate return the proper sorting (probably better as normal function than lambda):

int FirstHalfTableComparison(FirstHalfTable t1, FirstHalfTable t2)
{
    int result = t1.FirstHalfPoints.CompareTo(t2.FirstHalfPoints);

    if (result == 0)
    {
        result = t1.GD.CompareTo(t2.GD);

        if (result == 0)
            result = t1.GF.CompareTo(t2.GF);
    }

    return result;
}

You can use that like this:

firstHalfTables.Sort(FirstHalfTableComparison);

Upvotes: 2

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