Cannot save integer if it is empty.

Question

Hi , i'm developing a form to insert data in the Database (SQlServer 2005) i use Linq to Sql in WPF;

I have this database :

Column Name             Data Type          Allow Null
  CODE ID               Int(autoIncr)          No
  BoatName              Nvarchar(100)          No
  BoatType              Nvarchar(50)           yes
  NumberOfSeats         Int                    yes
 And so on...

Now when i insert a new record in my form if i leave empty the TextBox "txtNumberOfSeats" that refer to field "NumberOfSeat" in the database and when i click the button Save the database give me this error:"Input string was not in a correct format."

Why i cannot leave the field "NumberOfSeats " empty if i set up it in database AllowNull=Yes?

i post the code behind when i click the button Save to insert to new record in the database:

DataClassesDataContext dc = new DataClassesDataContext();
Boat_TBL boat = new Boat_TBL();
boat.BoatName = txtBoatName.Text;
boat.BoatType = txtBoatType.Text;
boat.NumberOfSeats = Int32.Parse(txtNumberOfSeats.Text);
dc.Boat_TBLs.InsertOnSubmit(boat);
dc.SubmitChanges;

DO you have any suggestion to work out this feature?

Thanks so much

Cheers

Answer 1

The call to Int32.Parse(...) fails when an empty string is passed to it. Provided that boat.NumberOfSeats is a nullable int, you should only set it when txtNumberOfSeats.Text is not an empty string.

Answer 2

You can pass null on the Data Access Layer when saving to your DB. e.g. try something like this:

if (String.isNullOrEmpty(txtNumberOfSeats.Text))
{
    NumberOfSeats = DBNull.Value;
}

Answer 3

You can use the integer tryParse method and output parameter can be use as no of seats..