C# Convert string to nullable type (int, double, etc...)
- by Nathan Koop
I am attempting to do some data conversion. Unfortunately, much of the data is in strings, where it should be int's or double, etc...
So what I've got is something like:
double? amount = Convert.ToDouble(strAmount);
The problem with this approach is if strAmount is empty, if it's empty I want it to amount to be null, so when I add it into the database the column will be null. So I ended up writing this:
double? amount = null;
if(strAmount.Trim().Length>0)
{
amount = Convert.ToDouble(strAmount);
}
Now this works fine, but I now have five lines of code instead of one. This makes things a little more difficult to read, especially when I have a large amount of columns to convert.
I thought I'd use an extension to the string class and generic's to pass in the type, this is because it could be a double, or an int, or a long. So I tried this:
public static class GenericExtension
{
public static Nullable<T> ConvertToNullable<T>(this string s, T type) where T: struct
{
if (s.Trim().Length > 0)
{
return (Nullable<T>)s;
}
return null;
}
}
But I get the error: Cannot convert type 'string' to 'T?'
Is there a way around this? I am not very familiar with creating methods using generics.
