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c#linq
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Reputation: 1065

Linq Filter IEnumerable against another IEnumerable

I have 2 classes

public class ClassA
{
    public int Id { get; set; }
    public string Name { get; set; }
}

And 

public class ClassB
{
    public int Id { get; set; }
    public string Name { get; set; }
    public ClassA ClassA { get; set; }
}

I am trying to filter a list of ClassB with a List of Class A

void Main()
    {

    var ListA = new List<ClassA>();
        var a1 = new ClassA() {Id=1, Name = "A1"};
    var a2 = new ClassA() {Id=2, Name = "A2"};
    var a3 = new ClassA() {Id=3, Name = "A3"};
    ListA.Add(a1);
    ListA.Add(a2);
    ListA.Add(a3);

    var FilterListA = new List<ClassA>();
    FilterListA.Add(a1);
    FilterListA.Add(a2);


    var ListB = new List<ClassB>();

    var b1 = new ClassB() {Id=1, Name="B1" ,ClassA= a1};
    var b2 = new ClassB() {Id=1, Name="B1", ClassA= a2};
    var b3 = new ClassB() {Id=1, Name="B1", ClassA= a3};
    var b4 = new ClassB() {Id=1, Name="B1", ClassA= a3};

    ListB.Add(b1);
    ListB.Add(b2);
    ListB.Add(b3);
    ListB.Add(b4);

it works if I use 

var query = from b in ListB
            join a in FilterListA
            on b.ClassA equals a
            select new { Name = b.Name, ClassAName = a.Name };

Console.WriteLine(query.ToList());

But I would like to do something like this... but i don't know how

Console.WriteLine(ListB.Where(o => o.ClassA IsIncluded In FilterListA));

}

I tried using Contains without success. thanks

Upvotes: 0

Views: 4592

Answers (1)

Kamil Budziewski
Kamil Budziewski

Reputation: 23087

This should works:

ListB.Where(x=>FilterListA.Any(y=>y==x.ClassA));

It gets all elements from ListB which have equivalent element in FilterListA. If object of ClassA included in element of list is listed in FilterListA it's returned.

EDIT: as gunr2171 said you can use Contains

ListB.Where(x=>FilterListA.Contains(x.ClassA));

Upvotes: 3

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