在LINQ中将datetime2转换为字符串（“ dd / MM / yyyy”）

Question

I have a datetime2 column in the database.I'm trying to fetch that from database and I want to display it in the view as string.

I tried: dt.ToString("dd/MM/yyyy");

But it gave an error.

An exception of type 'System.NotSupportedException' occurred in EntityFramework.SqlServer.dll but was not handled in user code

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

I tried String.Format("{0:y yy yyy yyyy}", dt); also, even this throwed an error.

Answer 1

you can check this site : click here

DateTime dt = new DateTime(2008, 3, 9, 16, 5, 7, 123);

String.Format("{0:y yy yyy yyyy}", dt);  // "8 08 008 2008"   year
String.Format("{0:M MM MMM MMMM}", dt);  // "3 03 Mar March"  month
String.Format("{0:d dd ddd dddd}", dt);  // "9 09 Sun Sunday" day
String.Format("{0:h hh H HH}",     dt);  // "4 04 16 16"      hour 12/24
String.Format("{0:m mm}",          dt);  // "5 05"            minute
String.Format("{0:s ss}",          dt);  // "7 07"            second
String.Format("{0:f ff fff ffff}", dt);  // "1 12 123 1230"   sec.fraction
String.Format("{0:F FF FFF FFFF}", dt);  // "1 12 123 123"    without zeroes
String.Format("{0:t tt}",          dt);  // "P PM"            A.M. or P.M.
String.Format("{0:z zz zzz}",      dt);  // "-6 -06 -06:00"   time zone

and Basically, in entityframework has no idea how to translate an object of System.Threading.Tasks.Task to a SQL statement.you can use :

SqlFunctions.StringConvert(dt)

or before using tostring(), use .tolist():

.ToList().select(p=>new{date=dt.ToString()});

Answer 2

I think I realize your problem, after you posted the screenshot. Some functions aren't allowed to run inside the linq, as linq needs to translate them to sql.

Since I can't copy paste your code with my modifications (you need to perform the date formatting outside the linq statement, whether using a foreach loop, or any other method). A rough idea:

allclient = (from ....
             select new AllClient()
             {
              ...
              PurchaseDT = "",
              PurchaseDate = k.PurchaseDate, //the formatting will be done later
             }
foreach (AllClient c in allclient)
      c.PurchaseDT = String.Format("{0:y yy yyy yyyy}", c.PurchaseDate); //or whatever other formatting you want

where PurchaseDate is of type DateTime and PurchaseDT is of type string.

First save the value coming from db to a datetime variable and later loop through the list using a foreach loop,convert the datetime variable into string and assign it to the string variable.

Updated

The only way will involve you adding one more variable to the AllClient class, if you can. This will be a DateTime to temporarily store the date, with another one as string (as shown in the code snippet above), which will be updated with the formatted date after the linq statement.

OR

Keep a single DateTime PurchaseDT , and instead of formatting it in linq or immediately afterwards, only format it when you are displaying it. For example, if you're displaying the records on a table of some kind, while displaying the date column, do the formatting on PurchaseDT there.

Answer 3

try this :

dt.ToString("d");

please note : the "d" format is Culture aware, but it gives you short date pattern.

Answer 4

DateTime dt = DateTime.ParseExact(<datetime string from db>, <format of date in Datetime string from db>, CultureInfo.InvariantCulture);
string formattedDate = dt.ToString("dd/MM/yyyy",CultureInfo.InvariantCulture);

First you have to convert the datetime string to a DateTime object then you can Convert to required format. The overload of ToString you are using is valid for DateTime object and not for a String object.That's the reason for the error

Answer 5

You can use this for the View :

@model.RegisteredDate.ToString("dd MMMM , yyyy")

This will give 21 August , 2016 of Format.
If you refer 21 Aug , 2016 then just use "MMM"