How to manage parsing an null object for DateTime to be used with ADO.NET as DBNULL

Question

I have two DateTime objects, BirthDate and HireDate. They are correctly formatted as a string and when I pass them through to my data access layer, they need to be parsed into a DateTime object.

DateTime hD = DateTime.Parse(hire);            
DateTime bD = DateTime.Parse(birth);

//incase of a datestring being passed through
dateStringPassed = "7/2/1969";

But sometimes, the strings hire and birth are null or empty "", if the code is run like this, I get a FormatException error from Parsing a empty string. How can I manage empty parses and allow the DateTime, if empty or null, be accepted as DBNull.Value?

I still cannot manage incase the user does not pass through a DateTime string, then the parse crashes my code.

My parameter for birth date is as follows and checks the variable if null, then use DBNull.Value.

Answer 1

The Parse method can't handle empty strings, but you can use nullable DateTime and do something like this:

DateTime? hD = String.IsNullOrEmpty(hire) ? (DateTime?)null : DateTime.Parse(hire)

But even safer would be using TryParse instead:

DateTime? hD = null;
DateTime.TryParse(hire, out hD);

Then for storing this value, you can test hD.HasValue:

if(hD.HasValue) { /* use hD */ }
else { /* else use DBNull.Value */ }

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Since C# 7, you can use shorter syntax for inline out parameters and you can avoid nullable type altogether:

if (DateTime.TryParse(hire, out var hD)) { /* use hD */ }
else { /* use DBNull.Value */ }