CODEWITHSUNDEEP
c#linq
Petar Sardelic
Petar Sardelic

Reputation: 69

How to extract a specific value from the linq query?

I am building a NET 5 API and am unable to extract and calculate something. I have a table StockTransaction which among other has property Quantity (I skipped some properties for brevity):

public class StockTransaction : BaseEntity
{      
    public int Id { get; set; }
    public decimal Price { get; set; }
    public int Quantity { get; set; }
    public bool Purchase { get; set; }
    public int Resolved { get; set; }       
}

Suppose I have 7 transactions, all of which are purchase:

List<StockTransaction> list = new List<StockTransaction>
{
new StockTransaction {Id = 1, Purchase = true, Quantity = 10, Resolved = 5, Price = 50},
new StockTransaction {Id = 2, Purchase = true, Quantity = 5, Resolved = 5, Price = 70},
new StockTransaction {Id = 3, Purchase = true, Quantity = 8, Resolved = 8, Price = 25},
new StockTransaction {Id = 4, Purchase = true, Quantity = 7, Resolved = 5, Price = 77},
new StockTransaction {Id = 5, Purchase = true, Quantity = 1, Resolved = 1, Price = 23},
new StockTransaction {Id = 6, Purchase = true, Quantity = 3, Resolved = 0, Price = 14},
new StockTransaction {Id = 7, Purchase = true, Quantity = 2, Resolved = 0, Price = 17},           
};

And I would like to get the value of the last 7 quantities, which in this case gives 176 ((2 x 17) + (3 x 14) + (1 x 23) + (1 x 77)). (How) can this be done? Every help and hint is more then appreciated...

Upvotes: 2

Views: 606

Answers (2)

Harkirat singh
Harkirat singh

Reputation: 765

You can use

var last3=list.OrderByDescending(x=>x.CreatedDate).Take(3).Select(x=>x.Quantity * x.Price).Sum();

var requiredSum=last3+list.Where(x=>x.id==4).Select(x=>x.Price).FirstOrDefault();

Upvotes: 1

SomeBody
SomeBody

Reputation: 8743

Although you have tagged your question with LINQ, do it with a normal loop:

private static decimal SumOfLastTransaction(IEnumerable<StockTransaction> stockTransactions, int max)
    {
        decimal result = 0;
        int sum = 0;
        foreach(var stockTransaction in stockTransactions.OrderByDescending(x => x.Id))
        {
            
            if(sum + stockTransaction.Quantity <= max)
            {
                result += stockTransaction.Quantity * stockTransaction.Price;
                sum += stockTransaction.Quantity;
            }
            else
            {
                result += (max - sum) * stockTransaction.Price;
                return result;
            }
        }
        return result;
    }

You loop over the last items in your list. You sum the amount of transactions and check whether it is smaller than your maximum. As long as they are smaller, you can add the amount of transactions. If not, you check how much is missing until your maximum is reached and substract this from your quantity.

Online demo: https://dotnetfiddle.net/9oM4pj

Upvotes: 0

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