How to check if all items belong to same type using LINQ

Question

public class  Product
{
public string Name {set; get;}
public string Type {set; get;}
}

public class ProductType
{
public string Name{get;set}
}


var products = GetProducts();
var productTypes = GetProductTypes(); 

bool isValid = products.All(x=>x.Type == ??) // Help required

I want to make sure that all products in the 'products' belong to only of the product type.

How could achieve this in linq. Any help is much appreciated I am struck with LINQ stuff ? Thanks.

Answer 1

You could use Distinct and Count:

isValid = products.Select(x => x.Type).Distinct().Count() == 1;

Answer 2

You can check if all items have the same type as the first item:

bool isValid = products.All(x => x.Type == products.First().Type);

Answer 3

var isValid = products.Select(p => p.Type).Distinct().Count() == 1;

or

var first = products.FirstOrDefault();
var isValid == (first == null) ? true : products.All(p => p.Type == first.Type);