How to fix an error 'Object reference not set to an instance of an object.'?

Question

Hi all,

I have a dataGrid and I am trying to get data from it like ...

int ID = Convert.ToInt32((dtgClients.SelectedItem as Client).id);

But it get me an error 'Object reference not set to an instance of an object.' and I dont know how to fix it.

Can you help me? Thanks.

Answer 1

Hi,@Puskas Filip, PravBcEx14. Welcome Microsoft Q&A.

The error message "Object reference not set to an instance of an object" typically occurs when you try to access a property or method on an object that is currently null. In the context of your code, this error likely happens when dtgClients.SelectedItem or (dtgClients.SelectedItem as Client) is null.

To fix this issue, you could add a null check to ensure that dtgClients.SelectedItem is not null before trying to access its properties.

if (dtgClients.SelectedItem != null)
{
    
    if (dtgClients.SelectedItem is Client selectedClient)
    {
        int ID = Convert.ToInt32(selectedClient.id);
      
    }
    else
    {
        // Handle the case where the selected item is not a 'Client'
        ...
    }
}
else
{
    // Handle the case where nothing is selected in the dataGrid
   
}

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