Select object and add to list linq c#

Question

probably a simple Q but still a beginner at this and not sure on how to.... Each WorkStation can have a number of Invoices So my below code will....

store all the workStations, go Through each workStation,
get the last (most recent) invoice for that workStation,
If the invoices date (for the most recent Invoice) is < 12 Months

Add it to the list of sites...

EDIT: Thanks for all the help guys but I am trying to do it through c# and avoid the LINQ searche you guys have mentioned...thanks for everyone who replied...

My new problem being i need to sort the ChosenInvoices list into asceding order and return the first...as i think it is selecting anyone in the list:

 var allWorkSites =
            (from worksites in db.Work_Sites
             select worksites).Distinct().ToList();
    List<Object> chosenInvoices = new List<Object>();

    foreach (Work_Site worksite in allWorksites)
    {
        Invoice lastInvoice = worksite.Invoices.LastOrDefault();

        if (lastInvoice != null)
        {
            if (lastInvoice.Invoice_Date < DateTime.Now.AddMonths(-12))
            {
                chosenInvoices.Add(workstation);
            }
        }
    }

add what to the list of sites? the invoice object or the workstation object? — Ravi Y
– Ravi Y, Commented Jan 24, 2013 at 13:28
what is list of sites? There nothing about it in your example — Ph0en1x
– Ph0en1x, Commented Jan 24, 2013 at 13:28
There is something off about your class/list design, you want go through all workstations and then get last invoice for each and then add an invoice to your list of workstations ? You need better naming of your classes, or need to relook at your logic. — Ravi Y
– Ravi Y, Commented Jan 24, 2013 at 13:32

Ph0en1x · Accepted Answer · 2013-01-24 14:18:33Z

4

List<invoice> actualInvoices = db.Work_Stations.Distinct()
        .Where(w => w.Invoices.Last().Invoice_Date < DateTime.Now.AddMonths(-12)).Select(w => w.Invoices.Last()).ToList();

This code will return you the list of most recent invoices from each workstation.

To sort your invoice in asscending order list have a method OrderBy(), so order it with this method and then take the first one.

Also list have Sort() method.

edited Jan 24, 2013 at 14:18

answered Jan 24, 2013 at 13:48

Ph0en1x

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2 Comments

Raphaël Althaus Over a year ago

I don't think you can be absolutely sure that Last() will return the element with the most recent date.

Ph0en1x Over a year ago

Think it's hard to say for sure because we know just a little about it. I still do not 100% sure that get the question right.

dutzu · Accepted Answer · 2013-01-24 13:41:12Z

2

allWorkStations
    .Where(w => w.Invoices.Last().Invoice_Date < DateTime.Now.AddMonths(-12))
    .Select(w => list.add(w));

Or better yet:

List<Work_Station> list = db.Work_Stations
    .Distinct()
    .Where(w => w.Invoices.Last().Invoice_Date < DateTime.Now.AddMonths(-12))
    .ToList();

edited Jan 24, 2013 at 13:41

answered Jan 24, 2013 at 13:30

dutzu

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Comments

daryal · Accepted Answer · 2013-01-24 13:32:16Z

1

var allWorkStations =
            (from workstation in db.Work_Stations
             where workstation.Invoices.Last().Invoice_Date < DateTime.Now.AddMonths(-12)
             select workstation).Distinct();

answered Jan 24, 2013 at 13:32

daryal

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Comments

Viacheslav Smityukh · Accepted Answer · 2013-01-24 13:35:36Z

1

The following code will create list of workstations which had invoice in last year

var checkDate = DateTime.Now.AddMonths(-12);

var resultList = db.Work_Stations
  .Distinct()
  .Select(ws => new {Ws = ws, Li = ws.Invoices.OrderBy(i => i.Invoice_Date).LastOrDefault()})
  .Where(item => item.Li != null && Li.Invoice_Date < checkDate)
  .Select(item => item.Ws)
  .ToList();

answered Jan 24, 2013 at 13:35

Viacheslav Smityukh

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Comments

D Stanley · Accepted Answer · 2013-01-24 13:38:26Z

1

This will work even if the invoices are not in date order:

invoiceLst.AddRange(allWorkStations
    .Where(w => w.Invoices.Max(i => i.Invoice_Date) < DateTime.Now.AddMonths(-12)));

answered Jan 24, 2013 at 13:38

D Stanley

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