How to Convert DropDownList items to check in linq query?

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I have a dropdownlist control in asp.net which contains dates from today to next 60 days and another dropdownlist control for time. Now, when a user selects a date from the dropdownlist control I call a method of SelectedItemChanged. I want to check that date from that database to get the times from another dropdownlist which is not saved in database. The problem is in the conversion I am not able to convert the items of dropdownlist which has dates to datetime so that I can check the value or item which is selected by the user in LINQ query.

I have tried many thinks as below:

C#

DateTime date = Convert.ToDateTime(DropDownListDate.SelectedValue);

var selectedDate = from d in datacontext.Appointment
                   where d.AppointmentDate == date
                   select d;

I also tried to store selected value in session but it didn't worked. I also tried the

C#

DateTime date = DateTime.Parse(DropDownlistDate.SelectedValue);

but it didn't worked as well. I want to convert the selected value from the dropdownlist control so that I can use that to check in the database and get the appropriate ans. Please Help. Any help is really appreciated.

Posted 7-Nov-14 0:47am

Amit Jangid

Updated 7-Nov-14 0:56am

v2

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Comments

KaushalJB 7-Nov-14 6:55am

What kind of value would you get from DropDownListDate.SelectedValue ?

Amit Jangid 7-Nov-14 7:05am

"String was not recognized as a valid DateTime."

This exception is displayed. If you can please provide me the codes it will be a great help to me. I just want to know how to convert the item which will be selected by the user to datetime so that I can use that in LINQ query to solve my problem.

3 solutions

Solution 1

SQL

var selectedDate = from d in datacontext.Appointment
                   where d.AppointmentDate.Contains( date)
                   select d;

Posted 7-Nov-14 2:42am

m.kolbadi

Solution 2

The error that you've already mentioned in the comments,

Quote:
String was not recognized as a valid DateTime.

means that the String that you're passing to the Convert.ToDateTime(argument); is not a valid dateTime object. There are actually many things you need to consider while writing a string that can be converted to a DateTime object.

The syntax of the string, the month and date sequence, usage of - or / might also raise this sort of error. It doesn't mean that your dateTime is not a human understandable dateTime but it means that the .NET framework doesn't understand the format of your DateTime.

For example if you use,

C#

// you wanted to write 12th november 2014, seems fair?
DateTime dateTime = new DateTime(12, 11, 2014);
// throws error

To minimize this error, you need to be passing the parameters as

C#

// 2014 year, 11 month and 12th day.
DateTime dateTime = new DateTime(2014, 11, 12);

Same stuff for the strings. While converting from String to a DateTime, you need to take a good care of the DateTime seperator (/ is used in .NET), the Month year day sequence etc. This document[^] of MSDN explains this concept a little bit accurately.

A sample code for you to pass a string would be,

C#

DateTime dateTime = Convert.ToDateTime("05/01/1996");
// converts to 5/1/1996 12:00:00 AM

Read this[^] article of mine to understand the DateTime in (a little bit) depth.

Posted 7-Nov-14 8:26am

Afzaal Ahmad Zeeshan

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Amit Jangid · Accepted Answer · 2014-11-22T01:19:00

Solution 3

This way I have converted the date from DropDownList and is working fine.

C#

DateTime date = Convert.ToDateTime(DropDownListDate.SelectedValue.ToString());

Posted 22-Nov-14 1:19am

Amit Jangid