Linq list orderby multiple lists of specific strings

Question

I have a list of type Test

List<Test> testList = new List<Test> 
    { new Test { TestName="gold", CriteriaOne = "sport", CriteriaTwo = "Outdoors" },
    { new Test { TestName="silver", CriteriaOne = "sport", CriteriaTwo = "Indoors" }, 
    { new Test { TestName="bronze", CriteriaOne = "activity", CriteriaTwo = "Water" }, 
    { new Test { TestName="gold", CriteriaOne = "activity", CriteriaTwo = "Outdoors" }, 
                     //some more tests  ...      };

I have a list for each criteria

// List of strings to order testListBy first.
List<String> criteriaOneOrder = new List<String> { "sport", "activity", "warmup", "other"};

//List of strings to order testListBy second.
List<String> criteriaTwoOrder = new List<String> { "OutDoors", "Indoors", "Water", "Other"};

I want to order by list of type test firstly based on the criteriaOneOrder list then if two results are the same, ie. more than one sport then order them on the second string so that a outdoor sport will be listed before indoor sport.

I've tried using Lambda expressions making use of the OrderyBy function and the IndexOf to try and reorder the list but have not been successful so far.

testList = testList.OrderBy(t => criteriaOneOrder.IndexOf(t.CriteriaOne)).ToList()

Any ideas?

Selman Genç · Accepted Answer · 2014-04-08 16:22:54Z

1

I would use enumarations to accomplish this:

enum CriteriaOne
{
    sport,
    activity,
    warmup,
    other
}

enum CriteriaTwo
{
    Outdoors,
    Indoors,
    Water,
    Other
}

var orderedList = testList
            .OrderBy(x => Enum.Parse(typeof (CriteriaOne), x.CriteriaOne))
            .ThenBy(x => Enum.Parse(typeof (CriteriaTwo), x.CriteriaTwo))
            .ToList();

If you change type of your properties to enum then you can simply do this:

var orderedList = testList
            .OrderBy(x => x.CriteriaOne)
            .ThenBy(x => x.CriteriaTwo)
            .ToList();

edited Apr 8, 2014 at 16:22

answered Apr 8, 2014 at 16:03

Selman Genç

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1 Comment

Tim S. Over a year ago

The parsing and casting is unnecessary. x => x.CriteriaOne is sufficient, and (IMO) perfectly clear.

maxp · Accepted Answer · 2014-04-08 15:58:19Z

0

Yep, its straightforward. Write a custom implementation of IComparer<string>, initialise it and pass it in as the second parameter for the LINQ OrderBy() method, and you are good to go.

answered Apr 8, 2014 at 15:58

maxp

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