Search list of object based on another list of object c#

Question

i have this class:

   class Ean
   {
        public string Code{ get; set; }
   }

   class Article
   {
        public int Id { get; set; }
        public string Name { get; set; }
        public List<Ean> BarCode { get; set; }
   }


   List<Article> arts = new List<Article>();
   List<Ean> eans = new List<Ean>();

I have a list of two objects. I need to check if in the list "arts.BarCode" there is one of the codes in the list eans. How can I do to make this search returns a Boolean value? Any help would be great! Thanks!

something like this would be perfect:

bool hasCheese = arts.Any(a => a.Name == "Cheese");

Jon Skeet · Accepted Answer · 2013-06-27 16:45:37Z

3

Well, you could just use:

bool hasCode = arts.Any(a => a.BarCode.Intersect(eans).Any());

That's assuming that either you want to treat each Ean object individually, or you've actually overridden Equals and GetHashCode appropriately.

It would be more efficient to create a set though:

var set = new HashSet<Ean>(eans);
bool hasCode = arts.Any(a => a.BarCode.Any(e => set.Contains(e)));

As an alternative approach, you could flatten your list to basically be a sequence of barcodes:

bool hasCode = arts.SelectMany(a => a.BarCode)
                   .Intersect(eans)
                   .Any();

That's actually probably the cleanest approach, as you don't care about which article has the matching barcode.

answered Jun 27, 2013 at 16:45

Jon Skeet

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3 Comments

puti26 Over a year ago

If i use the first give me an error : Value can not be null. Parameter name: first . Why ? Thanks

Jon Skeet Over a year ago

@enzop92: Well that suggests that one of your references is null. However, as you haven't even said which method call is failing, it's hard to tell you which... I suggest you look at your data carefully.

puti26 Over a year ago

Jon Thank you so much.. U are very kind !

spender · Accepted Answer · 2013-06-27 16:47:43Z

2

arts.SelectMany(a => a.BarCode).Intersect(eans).Any()

should be an efficient way of doing this, if I understand your problem correctly.

arts.SelectMany(a => a.BarCode)

flattens all the BarCode collections to an Enumerable<Ean>, which you can then intersect with your other collection and see if anything is left.

answered Jun 27, 2013 at 16:47

spender

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