Foreach loop and lambda expressions

Question

I have following Model Classes:

public class Promotion
{
     public Offers Offers { get; set; }    
}
public class Offers
{
    public List<PromotionOffer> Offer { get; set; }
}
public class PromotionOffer
{
    public string CategoryName { get; set; }
    public List<Product> Product { get; set; }
}

public class Product
{
    public string ProductName { get; set; }
}

I have Promotion object and a string allProducts.

Promotion promotion = promotion;
string allProducts = string.Empty;

I want to assign and append ProductName in allProducts where CategoryName == "Premium". Is it possible to achieve this using a lambda expression? or will be needing a foreach loop too? Pls guide, how I can I achieve this?

Possible duplicate of conditional Updating a list using LINQ — Tinwor
– Tinwor, Commented Nov 7, 2016 at 18:26
Are you saying you want to change the value of the existing ProductName properties? Or are you saying you want to append them all to allProducts? Or both? — 15ee8f99-57ff-4f92-890c-b56153
– 15ee8f99-57ff-4f92-890c-b56153, Commented Nov 7, 2016 at 18:29

Jonesopolis · Accepted Answer · 2016-11-07 18:29:17Z

4

promotion.Offers
         .Offer
         .Where(o => o.CategoryName == "Premium")
         .SelectMany(o => o.Product)
         .ToList()
         .ForEach(n => n.ProductName = n.ProductName + "AppendedString");

If you want to knock it out without a foreach loop, you can use List's ForEach method, along with LINQ

If you are actually wanting to just build a string of these product names, you'd use:

var strs = promotion.Offers
                    .Offer
                    .Where(o => o.CategoryName == "Premium")
                    .SelectMany(o => o.Product)
                    .Select(p => p.ProductName); 

var allProducts = string.Join(",", strs);

answered Nov 7, 2016 at 18:29

Jonesopolis

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Comments

clarkitect · Accepted Answer · 2016-11-07 18:30:26Z

3

Can be achieved with System.Linq and String.Join:

public static string ProductNameList(Promotion promotion, string category) {
    var products = promotion.Offers
        .Where(x => x.CategoryName == category)
        .SelectMany(x => x.Product)
        .Select(x => x.ProductName);
    return String.Join(", ", products);
}}

answered Nov 7, 2016 at 18:30

clarkitect

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1 Comment

Steve Over a year ago

Good answer, the only problem is the promotion.Offers.Where it should be promotion.Offers.Offer.Where

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