LINQ: How to select entire list of list by certain object property value

Question

It is probably an easy one but i could not find an answer.
I have List<List<myclass>> , how can i extract entire List by a specific value object property value?

for example, please see my draft code, how can i extract the entire (all the objects in that list) t2 List based on mc7 object properties?

I am only succeeding to extract mc7 object but not the List of it in result variable.

class myclass
{
    public DateTime SomeDate;
    public string SomeString;
}

static void Main(string[] args)
{
    List<List<myclass>> L = new List<List<myclass>>();
    List<myclass> t = new List<myclass>();

    myclass mc = new myclass() { SomeString = "5", SomeDate = DateTime.Now};
    myclass mc1 = new myclass() { SomeString = "12", SomeDate = DateTime.Now.AddDays(1) };
    myclass mc2 = new myclass() { SomeString = "123", SomeDate = DateTime.Now.AddDays(2) };
    myclass mc3 = new myclass() { SomeString = "77", SomeDate = DateTime.Now.AddDays(3) };
    myclass mc4 = new myclass() { SomeString = "882", SomeDate = DateTime.Now.AddDays(4) };

    t.Add(mc);
    t.Add(mc1);
    t.Add(mc2);
    t.Add(mc3);
    t.Add(mc4);

    L.Add(t);

    List<myclass> t2 = new List<myclass>();

    myclass mc5 = new myclass() { SomeString = "166", SomeDate = DateTime.Now.AddDays(500) };
    myclass mc6 = new myclass() { SomeString = "344", SomeDate = DateTime.Now.AddDays(501) };
    myclass mc7 = new myclass() { SomeString = "123", SomeDate = DateTime.Now.AddDays(502) };
    myclass mc8 = new myclass() { SomeString = "234", SomeDate = DateTime.Now.AddDays(503) };
    myclass mc9 = new myclass() { SomeString = "123", SomeDate = DateTime.Now.AddDays(504) };

    t2.Add(mc5);
    t2.Add(mc6);
    t2.Add(mc7);
    t2.Add(mc8);
    t2.Add(mc9);

    L.Add(t2);

    var target1 = "123";
    var date = DateTime.Now.AddDays(502).Date;

    var result = L.SelectMany(x => x)
        .Where(y => y.SomeString == target1 && y.SomeDate.Date == date).Select(x=>x).ToList();

}

Answer 1

You should avoid the usage of SelectMany since you are searching for a specific list:

var result = L
     .Where(l=>l.Any(y => y.SomeString == target1 && y.SomeDate.Date == date))
     .FirstOrDefault();

Answer 2

If you want the lists which contain at least one object that match your predicate:

var result = L.Where(list => list.Any(x => x.SomeString == target1 && x.SomeDate.Date == date)).ToList();

If you want only one list, replace the ToList with FirstOrDefault .

If you want the lists which contain at least one object that match your predicate and those list should only contain those objects, so all other non-matching objects are filtered out:

var result = L
    .Select(list => list.Where(x => x.SomeString == target1 && x.SomeDate.Date == date).ToList())
    .Where(list => list.Any())
    .ToList();