Convert null field to zero before converting to int?

In my program, I'm looping through a datatable to get data from each field. One line of my code looks like this:

int LYSMKWh = Convert.ToInt32(resultsDT.Rows[currentRow]["LYSMKWh"]);

Basically, I'm just taking the value that's in the cell and converting it to an int32. I run into a problem, though, when the data in the field is a null. I get an Invalid Cast error message about not being able to convert a "DBNull" to another type.

So, I know that I can just check the value of the field before I try to convert it by doing something like this:

if (resultsDT.Rows[currentRow]["LYSMKWh"] == null)
            {
                resultsDT.Rows[currentRow]["LYSMKWh"] = 0;
            }

But, is there a better way to do this? Is there something I can d开发者_开发问答o "inline" while I'm trying to convert the value without having to resort to using the if ?

EDIT: I did try using this suggested method:

int LYSMKWh = Convert.ToInt32(resultsDT.Rows[currentRow]["LYSMKWh"] ?? "0");

Unfortunately, I still received the Invalid Cast error message with regards to the DBNull type. It was suggested that I could have problems using the ?? operator if the types on either side were different.

Also, since I have complete control over the data that I'm building my datatable with, I changed it so that no null values would be written to any field. So, that pretty much negates the need to convert a null to an int32, in this case. Thanks for all the advice, everyone!

You could do this:

var LYSMKWh =
    resultsDT.Rows[currentRow]["LYSMKWh"].Equals(DBNull.Value)
    ? 0
    : Convert.ToInt32(resultsDT.Rows[currentRow]["LYSMKWh"]);

use the ?? operator:

resultsDT.Rows[currentRow][...] ?? "0"

(expecting the field to be a string - if not change the "0")

You may consider using C#'s ?? operator, which checks a value for null and if it's null, assigns a default value to it.

You can use the ?? operator:

object x = null;

int i = (int)(x ?? 0)

You can use a custom convert method:

public static int ConvertToInt32(object value, int defaultValue) {
    if (value == null)
        return defaultValue;
    return Convert.ToInt32(value);
}

You may need overloads that take other types, like string. You may have problems with the ?? operator if the types on either side are different.

You can replace it with a ternary operator:

var rowData = resultsDT.Rows[currentRow]["LYSMKWh"];
int LYSMKWh = rowData != null ? Convert.ToInt32(rowData) : 0;

Alternatively, the ?? operator could work:

int LYSMKWh = Convert.ToInt32(resultsDT.Rows[currentRow]["LYSMKWh"] ?? 0);

But I think that's less readable.

You can use extension Method.

int LYSMKWh = resultsDT.Rows[currentRow]["LYSMKWh"].IfNullThenZero();

Create the below class

public static class Converter
{
    public static Int32 IfNullThenZero(this object value)
    {
        if (value == DBNull.Value)
        {
            return 0;
        }
        else
        {
            return Convert.ToInt32(value);
        }
    }
}

Check if it's DBNull.Value instead of null:

if (resultsDT.Rows[currentRow]["LYSMKWh"] == DBNull.Value)
{
    resultsDT.Rows[currentRow]["LYSMKWh"] = 0;
}

The ternary expression would work like this:

var LYSMKwhField = resultsDT.Rows[currentRow]["LYSMKWh"];
int LYSMKWh = LYSMKwhField != DBNull.Value ? Convert.ToInt32(rowData) : 0;