如何在具有两个属性的对象列表中检查具有相同属性的所有对象是否也具有相同的其他属性？

Question

I have a list of Product s List<Product> productList , where:

public class Product
{
     int ProductId { get; set; }
     decimal Price { get; set; }
}

How do I check if in this productList all Product s with the ProductId also have the same Price ?

I found that this works:

bool result = productCheckList.GroupBy(p => p.ProductId).Any(gr => 
                     gr.Distinct().ToList().Count > 1)`;

But I also want to find out if one is not similar, which ones are not.

So when I have a List like this:

var list = new List<Product>
list.Add(new Product { ProductId = 1, Price = 2m }
list.Add(new Product { ProductId = 1, Price = 1m }

I want the method to return false, and show ProductId = 1.

Answer 1

The groups contains the products, not the prices for the products, so you would need to get the prices out:

bool result =
  productCheckList.GroupBy(p => p.ProductId)
  .Any(gr => gr.Select(pr => pr.Price).Distinct().Count() > 1);

To get the product groups where the prices differs:

List<IGrouping<int, Product>> result =
  productCheckList.GroupBy(p => p.ProductId)
  .Where(gr => gr.Select(pr => pr.Price).Distinct().Count() > 1)
  .ToList();