CODEWITHSUNDEEP
c#
rghazarian
rghazarian

Reputation: 260

Cast Collection Value Type

I have a collection of type Collection<Lookup<int>> and I would like to convert its values to Collection\Lookup<int?>>. What's the best way to do this?

Thank you

Upvotes: 3

Views: 207

Answers (4)

Brent Anderson
Brent Anderson

Reputation: 966

Assuming members A,B,C, this will convert the original collection to a new Collection<Lookup<int?>> and test the first value.

        var nowNullable = new Collection<Lookup<int?>>(lookup.Select(l => new Lookup<int?> {A = (int?) l.A, B = l.B, C = l.C}).ToArray());
        nowNullable.First().A = null;
        Console.WriteLine(nowNullable.First().A.HasValue);

Upvotes: 1

M.Babcock
M.Babcock

Reputation: 18965

System.Collection.ObjectModel.Collection<T> is related to IEnumerable<T> you should be able to use the Select extension method.

Something along the lines of:

var listOfNullables = lookupsAsInt.Select(l => new Lookup<Int?>(l.Value)).ToList();

You'll need to include using System.Linq; in your class file.

Upvotes: 2

Chris Shain
Chris Shain

Reputation: 51329

Assuming that Lookup<T> has a constructor that takes some value T and a property called Value that returns the T in question....

var lookupsAsNullableInt = lookupsAsInt.Select(l => new Lookup<Int?>(l.Value)).ToList();

The thing is, you'd need to know how to construct a single new Lookup<int?> from a single Lookup<int>. Then the above code does the work of transforming an enumeration of one into a List of the other.

Upvotes: 1

KeithS
KeithS

Reputation: 71565

Well, a Lookup is a collection of keyed IEnumerables; basically a read-only Dictionary<TKey, IEnumerable<TValue>>. A Lookup<int> is nonsensical.

Probably the best way to tackle this would be to "de-group" each item from the Lookups into an anonymous key-value pair with a nullable value, then re-group the items.

Example:

var myCollectionOfNullableInts =
   (from g in MyCollectionOfIntLookups
   from v in g.Values
   select new {g.Key, Value = (int?)v}
   into l
   group l by l.Key into g2
   select g2).ToList();

The resulting collection SHOULD be a List<Lookup<[your key type], int?>>.

Upvotes: 4

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