CODEWITHSUNDEEP
c#asp.netasp.net-mvclinqdatetime
Samy Sammour
Samy Sammour

Reputation: 2465

Error while converting nullable datetime to string in LINQ asp.net MVC

I am developing an asp.net MVC system with a Kendo UI. I have to send a "date" from a filter button in View to the controller and filter the LINQ. I used this code:

public ActionResult Grid_ReadLogAdminList([DataSourceRequest] DataSourceRequest request, string filterDate)
        {
            DateTime _temp;
            if (!DateTime.TryParse(filterDate, out _temp))
                _temp = DateTime.Now;

            return Json(_context.Entities<LogAdmin>().NoTracking().OrderByDescending(l => l.TimeStamp)
                .Where(f => f.TimeStamp.Value.ToString("dd.MM.yyyy") == _temp.ToString("dd.MM.yyyy"))
                .Select(l => new LogAdminInfo
                {
                    Id = l.Id,
                    Message = l.Message,
                    MessageTemplate = l.MessageTemplate,
                    Level = l.Level,
                    TimeStamp = l.TimeStamp,
                    Exception = l.Exception,
                    Properties = l.Properties,
                    LogEvent = l.LogEvent,
                })
                .ToDataSourceResult(request));
        }

but it gave me an error with the ".Where". you should know that TimeStamp field is "datetime?" nullable datetime.

I received this Error:

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

how can I fix the Error?

Upvotes: 1

Views: 787

Answers (3)

fubo
fubo

Reputation: 45967

replace

.Where(f => f.TimeStamp.Value.ToString("dd.MM.yyyy") == _temp.ToString("dd.MM.yyyy"))

with

.Where(f =>  DbFunctions.TruncateTime(f.TimeStamp) == _temp)

Upvotes: 1

YuvShap
YuvShap

Reputation: 3835

The error is pretty indicative LINQ to Entities does not support the ToString method, you should compare your dates using another approach.

Based on your code I assume you are only interested in the date part of the DateTime for comparison so I suggest you to try DbFunctions.TruncateTime Method:

Where(f => DbFunctions.TruncateTime(f.TimeStamp) == DbFunctions.TruncateTime(_temp))

Upvotes: 1

Franck Ngako
Franck Ngako

Reputation: 157

    var tempDate = _temp.ToString("dd.MM.yyyy")    
    Json(_context.Entities<LogAdmin>().NoTracking().OrderByDescending(l => l.TimeStamp)    
.Select(l => new LogAdminInfo
                    {
                        Id = l.Id,
                        Message = l.Message,
                        MessageTemplate = l.MessageTemplate,
                        Level = l.Level,
                        TimeStamp = l.TimeStamp.Value.ToString("dd.MM.yyyy"),
                        Exception = l.Exception,
                        Properties = l.Properties,
                        LogEvent = l.LogEvent,
                    }).Where(l => l.TimeStamp = tempDate).Select(l)
                    .ToDataSourceResult(request));

Upvotes: 0

Related Questions