Unable to cast object of type 'System.DBNull' to type 'System.String'.

Greetings!

Im a beginning developer that is used of programming in vb,but now im working with C# and i have a horrible error thatis driving me crazy for days.

I have a basic detailsview for inserting, but when i insert , i get te following error :

Unable to cast object of type 'System.DBNull' to type 'System.String'.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidCastException: Unable to cast object of type 'System.DBNull' to type 'System.String'.


Line 4947: get {
Line 4948: try {
Line 4949: return ((string)(this[this.tableEvenement.plaatsColumn]));
Line 4950: }
Line 4951: catch (global::System.InvalidCastException e) {




This is my BLL class :

public int InsertEvenement(String naam, String plaats, DateTime? datum,
string start,string einde, string status, int? populariteit, string expert,int? min,int? max, int? reserves)
{
//try
//{
CorePlanner.EvenementDataTable evenementen = new CorePlanner.EvenementDataTable();
CorePlanner.EvenementRow evenement = evenementen.NewEvenementRow();

evenement.naam = naam;


if (plaats == null) evenement.SetplaatsNull();
else evenement.plaats = plaats;


if (start == null) evenement.SetstartNull();
else evenement.start = start;

if (einde == null) evenement.SeteindeNull();
else evenement.einde = einde;

if (datum == null) evenement.SetdatumNull();
else evenement.datum = datum.Value;

if (min == null) evenement.SetminNull();
else evenement.min = min.Value;

if (max == null) evenement.SetmaxNull();
else evenement.max = max.Value;

if (reserves == null) evenement.SetreservesNull();
else evenement.reserves = reserves.Value;

evenement.status = status;


if (populariteit == null) evenement.SetpopulariteitNull();
else evenement.populariteit = populariteit.Value;

if (expert == null) evenement.SetexpertNull();
else evenement.expert = expert;


return Convert.ToInt32(Adapter.Inserteveneemnt (evenement.plaats, evenement.naam, evenement.expert, evenement.populariteit, evenement.status, evenement.einde, evenement.start, evenement.datum, evenement.min, evenement.max, evenement.reserves));



So if anyone could help, it would be wonderfull
Thnx

Senne Ceulemans

-->Thread moved to .NET Forum

hi Senne,
you have message in plain English.
this value:

is NULL, thus can't be converted to string.
correct logic would be: