Question

How can I convert DateTime into a formatted string?

This is the line in the following query that needs help:

StartDate = string.Format("{0:dd.MM.yy}", p.StartDate)

The whole query:

var offer = (from p in dc.CustomerOffer
             join q in dc.OffersInBranch
             on p.ID equals q.OfferID
             where q.BranchID == singleLoc.LocationID
             let value = (p.OriginalPrice - p.NewPrice) * 100 / p.OriginalPrice
             orderby value descending
             select new Offer()
             {
                 Title = p.OfferTitle,
                 Description = p.Description,
                 BestOffer = value,
                 ID = p.ID,
                 LocationID = q.BranchID,
                 LocationName = q.CustomerBranch.BranchName,
                 OriginalPrice = SqlFunctions.StringConvert((decimal)p.OriginalPrice),
                 NewPrice = SqlFunctions.StringConvert((decimal)p.NewPrice),
                 StartDate = string.Format("{0:dd.MM.yy}", p.StartDate)
             }).First();

I get the following error message:

LINQ to Entities does not recognize the method ‘System.String ToString(System.String)’ method, and this method cannot be translated into a store expression.

Answer 1

EDIT: Now that I understand the question, I’m giving it another shot 🙂

var offer = (from p in dc.CustomerOffer
                     join q in dc.OffersInBranch
                         on p.ID equals q.OfferID
                     where q.BranchID == singleLoc.LocationID
                     let value = (p.OriginalPrice - p.NewPrice) * 100 / p.OriginalPrice
                     orderby value descending
                     select new
                     {
                         Title = p.OfferTitle,
                         Description = p.Description,
                         BestOffer=value,
                         ID=p.ID,
                         LocationID=q.BranchID,
                         LocationName=q.CustomerBranch.BranchName,
                         OriginalPrice=SqlFunctions.StringConvert((decimal)p.OriginalPrice),
                         NewPrice=SqlFunctions.StringConvert((decimal)p.NewPrice),
                         StartDate=p.StartDate

                     })
                     .ToList()
                     .Select(x => new Offer()
                     {
                         Title = x.OfferTitle,
                         Description = x.Description,
                         BestOffer=value,
                         ID=x.ID,
                         LocationID=x.BranchID,
                         LocationName=x.CustomerBranch.BranchName,
                         OriginalPrice=x.OriginalPrice,
                         NewPrice=x.NewPrice,
                         StartDate=x.StartDate.ToString("dd.MM.yy")
                     }).First();

I know it’s a bit long, but that’s the problem with Linq To SQL.

When you use linq, the database call isn’t executed until you use something such as ToList() or First() that results in actual objects. Once that SQL call is executed by the first .First() call, you’re now working with .NET types, and can use DateTime stuff.