Casting Datareader Value To A To A Nullable Variable

Answer :

Use the "IsDbNull" method on the data reader... for example:

bool? result = dataReader.IsDbNull(dataReader["Bool_Flag"]) ? null : (bool)dataReader["Bool_Flag"] 

Edit

You'd need to do something akin to: bool? nullBoolean = null;

you'd have

bool? result = dataReader.IsDbNull(dataReader["Bool_Flag"]) ? nullBoolean : (bool)dataReader["Bool_Flag"] 

Consider doing it in a function.

Here's something I used in the past (you can make this an extension method in .net 4):

public static T GetValueOrDefault<T>(SqlDataReader dataReader, System.Enum columnIndex) {     int index = Convert.ToInt32(columnIndex);      return !dataReader.IsDBNull(index) ? (T)dataReader.GetValue(index) : default(T); } 

Edit

As an extension (not tested, but you get the idea), and using column names instead of index:

public static T GetValueOrDefault<T>(this SqlDataReader dataReader, string columnName) {      return !dataReader.IsDBNull(dataReader[columnName]) ? (T)dataReader.GetValue(dataReader[columnName]) : default(T); } 

usage:

bool? flag = dataReader.GetValueOrDefault("BOOL_COLUMN"); 

There's an answer here that might be helpful: https://stackoverflow.com/a/3308515/1255900

You can use the "as" keyword. Note the caution mentioned in the comments.

nullableBoolResult = dataReader["BOOL_FLAG"] as bool?; 

Or, if you are not using nullables, as in your original post:

boolResult = (dataReader["BOOL_FLAG"] as bool?) ?? 0;