CODEWITHSUNDEEP
c#winformslistview
jhoevenaars
jhoevenaars

Reputation: 183

Add list view item to listview control

I'm trying to fill a list view from a datatable but when I run the code I recieve a weird error that I can't figure out.

The code:

        DataTable allTracks = tracks.getByMedia();

        for (int i = 0; i < allTracks.Rows.Count; i++) {
            DataRow r = allTracks.Rows[i];

            ListViewItem lvi = new ListViewItem();
            lvi.Text = r["track_number"].ToString();
            lvi.SubItems.Add(r["track_name"].ToString());

            lvTracks.Items.Add(lvi);
        }

Error : 

  Object reference not set to an instance of an object.

The program thinks that the lvi variable is not set or null, but when I go into Debug mode, I can see that lvi is definitly initialized and set and is containing the 

right text + sub item . :S

Also if I put this instead of the 

lvTracks.Items.Add(lvi);
 Messagebox.Show(lvi.Text)

It shows the correct value, and does not trigger the error....

Upvotes: 0

Views: 535

Answers (2)

Akshita
Akshita

Reputation: 867

It seems the one of the fields contain a null value as converting null values to String Throws error.

I dont think Listviewitem is null in any case beacuase it gets intantiated every time in loop

try 

DataTable allTracks = tracks.getByMedia();

    foreach(DataRow r in allTracks.Rows) {

        string track_number= r["track_number"]!=System.DBNull.Value?r["track_number"].ToString():"";
        string track_name=r["track_name"]!=System.DBNull.Value?r["track_name"].ToString():"";
        ListViewItem lvi = new ListViewItem();
        lvi.Text = track_number;
        lvi.SubItems.Add(track_name);
        if(lvTracks!=null)
        {
        lvTracks.Items.Add(lvi);
        }
    }

Please note that there exists two different null One for .Net CLR this is 'null' and the other for Database that is 'Syatem.DBNull.Value'

Upvotes: 0

competent_tech
competent_tech

Reputation: 44921

There is nothing apparently wrong with the listviewitem; I suspect that the error is that one of your field names in the data row is incorrect.

Upvotes: 1

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