Update Linq's Many-Sql Attitude

Question

I use Linq for Sql and don’t know how to update the many-many relationship.

My scenario: A product is defined by one or more elements. When I create a Product, I just select the elements I need and they are added:

product.ProductItemRel.Add(itemRel);

But what is the best practice when I need to update?

I could make my own update function to find elements to remove and elements to insert, but it will easily take 20 lines of code.

Etc. quick and dirty:

var oldProduct = orderRepository.GetProductCRUD.FetchSingle(x => x.ProductID == product.ProductID);

//Add items
foreach (var i in items)
{       
    if(i not exist in oldProduct)
    {                    
        var itemRel = new ProductItemRel()
        {
            ItemID = i,
            Product = product
        };
        product.ProductItemRel.Add(itemRel);
    }
}

//Delete items                         
foreach(var p in oldProduct)
{
    if(p not exist in items)
    {
        product.ProductItemRel.Remove(relation to delete);
    }
}

Another and very bad way is to simply delete all relationships, add new ones.

What is the best practice in Linq to Sql when I need to update the many-many relationship?

Answer 1

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