System.FormatException: String was not recognized as a valid DateTime.

Question

Hello all,

I am using c#.net. Thanks in advance for any help.

I am using a Repeater and a ObjectDataSource. I use LINQ to connect to the database. This requires a parameter to be passed through (used within the WHERE clause)

    public IQueryable<comments> GetComments(DateTime todaysDate)
    {
        return (from c in dc.comments
                where displayDate.Date == todayDate.Date
                select c);
    }

I am encounting the error above and don't know why. Here is where the problem lies:

<asp:Parameter DefaultValue="<%=Convert.ToDateTime(DateTime.Now)%>" Name="todayDate" Type="DateTime" />

If I provide a actual date it works. For example:

<asp:Parameter DefaultValue="02/09/2009" Name="todayDate" Type="DateTime" />

I have also tried the following and recieved the same error:

DateTime.Now.Date
Datetime.Now
Datetime.Today
Datetime.Now.ToString
Datetime.Now.Date.ToString.

What am I doing wrong?

Thanks

Clare

Answer 1

You can add the SelectParameter in the page load. Just add this -

SqlDataSource1.SelectParameters["todayDate"].DefaultValue = Datetime.Now;

Edit: Thanks Hans for the correction.

Answer 2

If you've copied and pasted your code, then you might have a typo in the function - the function parameter is named today**s**Date, but the where statement uses todayDate (which is your ASP parameter).

If this is not the case, please post where you call your GetComments function from.

Answer 3

Are you sure this is the correct location of the error? Here is what Convert.ToDateTime does:

    public static DateTime ToDateTime(bool value)
    {
        return ((IConvertible) value).ToDateTime(null);
    }

DateTime is an IConvertible, and it implements ToDateTime very simply:

    DateTime IConvertible.ToDateTime(IFormatProvider provider)
    {
        return this;
    }

As Chris pointed out, there is no reason to convert DateTime.Now to a DateTime. It already is one.

Answer 4

Using <%= .. %> syntax in a server control () is not possible. Use code-behind to set the property.

Answer 5

Thank you everyone for you help. You put me on the right track.

After finding out I could set the DefaultValue within the code behind I have another look around the web and found this tutorial.

This is now working.

Here is my code:

    protected void comments_Selecting(object sender, ObjectDataSourceSelectingEventArgs e)
    {
        e.InputParameters["todayDate"] = DateTime.Now;
    }

However please note first you must create a 'Selecting' event (within the properties tab).

I hope this is the correct way of doing it. Does anyone have any comments on this?

Thanks again

Clare