How can I move on column data to another column in the same row using linq

Question

I am working an an old project which has to do with invoices.

My problem is that the previous programmer put some values in the wrong column.

To be more specific he put the total amount in column 'credit' instead of column 'charge'.

I want to fix those values andmove them to the correct column using linq but I don't know how to do it. I've searched on the internet but I couldn't find something similar.

I am using this code to get the invoices for the customer

foreach (Customer customer in CustomerList)
{
    foreach (KartelesPelaton p in customer.KartelesPelaton.OrderBy(p => p.Imerominia))
    {
        if (p.IsInvoice)
        {

            if (p.Credit.HasValue)
            {
                //Change this record data from p.Credit to p.Charge
            }
        }
    }
}

Not sure I get what you're asking, can you provide a runnable example please? — Haytam, Apr 10 '19 at 11:15
What is `Customer`? What is `CustomerList`? What is `KartelesPelaton`? Also keep in mind that LINQ is for querying. But you can query data in the new format and replace old data with the result. — Sergey Berezovskiy, Apr 10 '19 at 11:17
please convert the greeklish var names to english, so it can be more easy to understand. — Grigoris Loukidis, Apr 10 '19 at 11:19

score 3 · Accepted Answer · edited Apr 10 '19 at 11:50

3

Is the following code what you need?

foreach (Customer customer in CustomerList)
{ 
    foreach (KartelesPelaton p in customer.KartelesPelaton.OrderBy(p => p.Imerominia))
    {
        if (p.IsInvoice)
        {
            if (p.Credit.HasValue)
            {
                p.Charge = p.Credit;
                p.Credit = null;
            }
        }
    }
}

edited Apr 10 '19 at 11:50

kara

3,205
4
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34

answered Apr 10 '19 at 11:22

Amir Molaei

3,700
1
17
20

Great.Thank you. That's exactly what I wanted. I didn't believe it was that easy. In fact I made that before but I forgot to make the 'credit' column null so it gave me the same result so I thought I made it wrong and I had to save the changes. – rippergr Apr 10 '19 at 11:34

kara · Answer 2 · 2019-04-10T11:50:55.110

As mentioned in the comments Linq is for querying and not for looping.

If you want a "cool" Foreach you could do it with Parallel.Foreach:

Parallel.ForEach(CustomerList.SelectMany(c => c.KartelesPelaton), k => { if (k.IsInvoice) k.Charge = k.Credit; k.Credit = 0; });

Full example

public class Customer
{
    public int Id { get; set; }
    public List<KartelesPelaton> KartelesPelaton { get; set; }

    public override string ToString() => "Id " + this.Id + ":" + String.Join(", ", this.KartelesPelaton.Select(s => s));
}

public class KartelesPelaton
{
    public bool IsInvoice { get; set; }
    public int Credit { get; set; }
    public int Charge { get; set; }

    public override string ToString() => "Is " + (this.IsInvoice ? "" : "NOT ") + "Invoice! " + Credit + " - " + Charge;
}

public static void Main(string[] args)
{
    // Some example-data..
    List<Customer> CustomerList = new List<Customer>()
    {
        new Customer() { Id = 1, KartelesPelaton = new List<KartelesPelaton>() { new KartelesPelaton() { IsInvoice = false, Credit = 1 } } },
        new Customer() { Id = 2, KartelesPelaton = new List<KartelesPelaton>() { new KartelesPelaton() { IsInvoice = true, Credit = 2 }, new KartelesPelaton() { Credit = 22 } } },
        new Customer() { Id = 3, KartelesPelaton = new List<KartelesPelaton>() { new KartelesPelaton() { IsInvoice = true, Credit = 3 } } },
    };

    // Let's see what we got..
    Console.WriteLine("Before:");
    foreach (Customer c in CustomerList)
    {
        Console.WriteLine(c);
    }

    // Select items to modify (customers seem not to be important here..)
    var itemsToModify = CustomerList.SelectMany(c => c.KartelesPelaton);
    // Process the items
    Parallel.ForEach(itemsToModify, k => { if (k.IsInvoice) k.Charge = k.Credit; k.Credit = 0; });

    Console.WriteLine("After:");
    foreach (Customer c in CustomerList)
    {
        Console.WriteLine(c);
    }
}

What difference would it make to use the Parallel.Foreach instead of foreach — rippergr, Apr 10 '19 at 11:40
You process your jobs parallel in multiple threads. But it's only needed if you got very much work: https://stackoverflow.com/questions/6036120/parallel-foreach-slower-than-foreach — kara, Apr 10 '19 at 11:48

How can I move on column data to another column in the same row using linq

2 Answers2

Full example