C# using LINQ, from a list of objects, create a new list of objects, removing ones whose property is in a list of stings

Question

I have an object like this -

public MyObject
{
    public int Id { get; set; } 
    public string MyType { get; set; }
}

a list of those objects -

public List<MyObject> MyObjectList { get; set; }

and a list of string like this -

public List<string> MyTypeList { get; set; }

Using LINQ on MyObjectList, I want to create a list of MyObject removing any MyObject that has a MyObject.MyType that is in the MyTypeList.

Something like this (here are some unsuccessful attempts) -

List<MyObject> MyObjectListNEW = MyObjectList.Select(i => i.MyType).Except(MyTypeList).ToList();
List<MyObject> MyObjectListNEW = MyObjectList.Where(i => i.MyType.Except(MyTypeList));

List<MyObject> MyObjectListNEW = MyObjectList.Where(i => !MyTypeList.Any( t => t == i.MyType)).ToList(); — Chetan
– Chetan, Commented Oct 19, 2021 at 15:59

Hazrelle · Accepted Answer · 2021-10-19 16:00:29Z

1

This should work:

var MyObjectList = new List<MyObject>();
var MyTypeList = new List<string>();
var results = MyObjectList.Where(m => !MyTypeList.Any(t => m.MyType == t)).ToList();

answered Oct 19, 2021 at 16:00

Hazrelle

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1 Comment

Jeppe Stig Nielsen Over a year ago

Instead of .Any(t => expr == t) it is often better to write .Contains(expr). The latter can go to an ordinary instance method if this is used directly on an ICollection<> or similar (which is the case in the current question), or can go to Linq's extension method Contains<TSource> in situations where we have nothing better than an IEnumerable<> as source.

Soner from The Ottoman Empire · Accepted Answer · 2021-10-19 16:39:02Z

0

I think it should be

var results = MyObjectList.Where(m => ! MyTypeList.Contains(m.MyType)).ToList();

answered Oct 19, 2021 at 16:39

Soner from The Ottoman Empire

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Comments

Serge · Accepted Answer · 2021-10-19 17:34:30Z

0

try this

var results = MyObjectList.Where(m =>  !MyTypeList.Contains(m.MyType)).ToList();

edited Oct 19, 2021 at 17:34

answered Oct 19, 2021 at 16:24

Serge

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