Question

When a this function is given an id that in SQL returns 0 rows I get the error below:

The null value cannot be assigned to a member with type System.Decimal which is a non-nullable value type.

What is the best way to modify the query to prevent this. I am pulling the value from a different table than I am querying here, so I would like to be able to handle giving it a “bad” id.

    public decimal GetSumOfValuesForAccount(Guid companyId)
    {
        return (from o in _context.Details
                where o.CustomerID == companyId
                select o).Sum(p => p.SomeValue.GetValueOrDefault());
    }

Returns the error:

Answer 1

you should be able to either return:

return (from o in _context.Details
                where o.CustomerID == companyId
                select o).Sum(p => p.SomeValue) ?? -1.0;

or

decimal? temp = (from o in _context.Details
                where o.CustomerID == companyId
                select o).Sum(p => p.SomeValue);
return temp ?? -1.0;

The ?? operator will check for null, and if null, return the next value.