Enumerable.SelectMany<TSource, TCollection, TResult> Method (IEnumerable<TSource>, Func<TSource, IEnumerable<TCollection>>, Func<TSource, TCollection, TResult>)

Type Parameters

• TSource
  The type of the elements of source.

• TCollection
  The type of the intermediate elements collected by collectionSelector.

• TResult
  The type of the elements of the resulting sequence.

Parameters

• source
  Type: System.Collections.Generic.IEnumerable<TSource>
  A sequence of values to project.

• collectionSelector
  Type: System.Func<TSource, IEnumerable<TCollection>>
  A transform function to apply to each element of the input sequence.

• resultSelector
  Type: System.Func<TSource, TCollection, TResult>
  A transform function to apply to each element of the intermediate sequence.

Return Value

Type: System.Collections.Generic.IEnumerable<TResult>
An IEnumerable<T> whose elements are the result of invoking the one-to-many transform function collectionSelector on each element of source and then mapping each of those sequence elements and their corresponding source element to a result element.

   Structure PetOwner
      Public Name As String
      Public Pets() As String
   End Structure

   Sub SelectManyEx3()
      ' Create an array of PetOwner objects.
      Dim petOwners() As PetOwner = _
          {New PetOwner With _
           {.Name = "Higa", .Pets = New String() {"Scruffy", "Sam"}}, _
           New PetOwner With _
           {.Name = "Ashkenazi", .Pets = New String() {"Walker", "Sugar"}}, _
           New PetOwner With _
           {.Name = "Price", .Pets = New String() {"Scratches", "Diesel"}}, _
           New PetOwner With _
           {.Name = "Hines", .Pets = New String() {"Dusty"}}}

      ' Project an anonymous type that consists of
      ' the owner's name and the pet's name (string).
      Dim query = _
          petOwners _
          .SelectMany( _
              Function(petOwner) petOwner.Pets, _
              Function(petOwner, petName) New With {petOwner, petName}) _
          .Where(Function(ownerAndPet) ownerAndPet.petName.StartsWith("S")) _
          .Select(Function(ownerAndPet) _
                 New With {.Owner = ownerAndPet.petOwner.Name, _
                           .Pet = ownerAndPet.petName _
                 })

      Dim output As New System.Text.StringBuilder
      For Each obj In query
         output.AppendLine(String.Format("Owner={0}, Pet={1}", obj.Owner, obj.Pet))
      Next

      ' Display the output.
      outputBlock.Text &= output.ToString() & vbCrLf
   End Sub

   ' This code produces the following output:
   '
   ' Owner=Higa, Pet=Scruffy
   ' Owner=Higa, Pet=Sam
   ' Owner=Ashkenazi, Pet=Sugar
   ' Owner=Price, Pet=Scratches

      class PetOwner
      {
         public string Name { get; set; }
         public List<string> Pets { get; set; }
      }

      public static void SelectManyEx3()
      {
         PetOwner[] petOwners =
                 { new PetOwner { Name="Higa", 
                       Pets = new List<string>{ "Scruffy", "Sam" } },
                   new PetOwner { Name="Ashkenazi", 
                       Pets = new List<string>{ "Walker", "Sugar" } },
                   new PetOwner { Name="Price", 
                       Pets = new List<string>{ "Scratches", "Diesel" } },
                   new PetOwner { Name="Hines", 
                       Pets = new List<string>{ "Dusty" } } };

         // Project the pet owner's name and the pet's name.
         var query =
             petOwners
             .SelectMany(petOwner => petOwner.Pets, (petOwner, petName) => new { petOwner, petName })
             .Where(ownerAndPet => ownerAndPet.petName.StartsWith("S"))
             .Select(ownerAndPet =>
                     new
                     {
                        Owner = ownerAndPet.petOwner.Name,
                        Pet = ownerAndPet.petName
                     }
             );

         // Print the results.
         foreach (var obj in query)
         {
            outputBlock.Text += obj + "\n";
         }
      }

      // This code produces the following output:
      //
      // {Owner=Higa, Pet=Scruffy}
      // {Owner=Higa, Pet=Sam}
      // {Owner=Ashkenazi, Pet=Sugar}
      // {Owner=Price, Pet=Scratches}