Question

I have a Datetime object which I take from an XML file (closingDate).

I want to dynamically display all closingDates to the user. However, not all objects in the XML file necessarily contain a dateobject.

How can I do this (pseudocode):

DateTime closingDate = DateTime.Parse(xmlFile.selectSingleNode("Closing_Date")).toString();

and then later, I am writing out an HTML file with:

    String fileListHTML += "<li><a href='#'>The file name gets put here</a> (Closed:
"+closingDate+")</li>";

Now, as long as there is a datetime, there is no issue. However, if there is no datetime object (ie: null), I get an error.

Can I somehow do an if statement to say (again, pseudo):

if (closingDate =="")
{
   closingDate = "To be determined";
}

I am, of course, getting an error about casting a datetime to string.
Is there a way to do this?

Answer 1

I’m not a fan of turning DateTimes to strings until it is necessary.

You could use a nullable DateTime. Use null to denote it’s not set or parsable. Alternatively scratch the nullable approach and use a sentinel such as DateTime.MinValue instead.

This is untested but should get the point across:

DateTime? closingDate;

if (!string.IsNullOrEmpty(myClosingDateString))
{
    closingDate = DateTime.Parse(myClosingDateString);
}

// do whatever else you need

// when it comes time to appending ...

if (!closingDate.HasValue) // or check if it's `DateTime.MinValue`
{
    fileListHtml += "No closing date";
}
else
{
    fileListHtml += closingDate.Value.ToString();
}

I’d caution you to be careful about converting DateTime to strings without considerations to time zones and internationalization (for example, DateTime.Parse() can interpret dates very differently depending on regional settings and/or the culture you pass in).

For simplicity, if you can control the format of the string, I’d suggest using UTC and the ISO 8601 format.