CODEWITHSUNDEEP
c#linq
PassionateDeveloper
PassionateDeveloper

Reputation: 15138

Group by and sort by three different version parts

I have following data:

Name - Mayor Version - Minor Version - Build version
X - 1 - 0 - 0
X - 1 - 1 - 0
X - 2 - 0 - 0
Y - 0 - 2 - 3
Y - 0 - 1 - 1
Z - 4 - 4 - 4

Now I want to get the highest Version Number with Mayor > Minor > Build grouped by name.

So the output here should be:
X - 2 - 0 - 0
Y - 0 - 2 - 3
Z - 4 - 4 - 4

How to do that in linq? I tried to group by Name and then do a sort by Mayor, then by minor then by build and take the first() but I can't figure out the syntax here...

Upvotes: 0

Views: 128

Answers (1)

Guru Stron
Guru Stron

Reputation: 142903

You can use OrderByDescending followed with chained ThenByDescending calls in Select statement after GroupBy:

class Version
{
    public string Name {get;set;} 
    public int MajorVersion {get;set;}
    public int MinorVersion {get;set;}
    public int BuildVersion {get;set;}
}

List<Version> versions = ...;
versions
    .GroupBy(x => x.Name)
    .Select(g => g.OrderByDescending(g => g.MajorVersion)
                    .ThenByDescending(g => g.MinorVersion)
                    .ThenByDescending(g => g.BuildVersion)
                    .First())
    .ToList();

Or try leverage default value tuple comparer:

versions
    .GroupBy(x => x.Name)
    .Select(g => g.OrderByDescending(g => (g.MajorVersion, g.MinorVersion, g.BuildVersion))
            .First())
    .ToList();

Upvotes: 3

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