object cannot be cast from dbnull to other types. c#

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C#

private void dgv_Add_job_card_DoubleClick(object sender, EventArgs e)
       {
           txt_Items_No.Text = this.dgv_Add_job_card.CurrentRow.Cells[0].Value.ToString();
           txt_Job_card.Text = this.dgv_Add_job_card.CurrentRow.Cells[1].Value.ToString();
           txt_Value_Part.Text = this.dgv_Add_job_card.CurrentRow.Cells[2].Value.ToString();
           CB_Auto_parts.Text = this.dgv_Add_job_card.CurrentRow.Cells[3].Value.ToString();
           if (Convert.ToInt32(this.dgv_Add_job_card.CurrentRow.Cells[4].Value) == 0)
           {

               radioButton_New.Checked = true;

           }
           else
           {

               radioButton_old.Checked = true;
           }
           CB_Providers_desc.Text = this.dgv_Add_job_card.CurrentRow.Cells[5].Value.ToString();
           CB_Hand_installation.Text = this.dgv_Add_job_card.CurrentRow.Cells[6].Value.ToString();
           txt_Notes.Text = this.dgv_Add_job_card.CurrentRow.Cells[7].Value.ToString();
           CB_Repair_type.Text = this.dgv_Add_job_card.CurrentRow.Cells[10].Value.ToString();
           dgv_Add_job_card.Rows.RemoveAt(dgv_Add_job_card.CurrentRow.Index);
           txt_Value_Part.Focus();
       }

Posted 30-Jan-16 7:02am

Member 12244977

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PIEBALDconsult · Accepted Answer · 2016-01-30T07:19:00

Indeed, it can't.

I suspect you're getting that due to:
Convert.ToInt32(this.dgv_Add_job_card.CurrentRow.Cells[4].Value)

First off, do NOT use Convert.ToInt32 .

Next, try this instead (if the value is an integer):

C#

if ((this.dgv_Add_job_card.CurrentRow.Cells[4].Value is int) && ((int)this.dgv_Add_job_card.CurrentRow.Cells[4].Value == 0))

Or this (if the value is a bit/boolean):

C#

if ((this.dgv_Add_job_card.CurrentRow.Cells[4].Value is bool) && (bool)this.dgv_Add_job_card.CurrentRow.Cells[4].Value))

Furthermore, if the other values are strings, do NOT use ToString on them; just cast them.

Sascha Lefèvre · Accepted Answer · 2016-01-30T07:25:00

Here:

C#

if (Convert.ToInt32(this.dgv_Add_job_card.CurrentRow.Cells[4].Value) == 0)

..that cell holds a DBNull-value (the single instance of DBNull to be exact) which probably originates from reading from your database. It can't be converted or cast to anything (other than Object). You have to check for it before attempting to check for being equal to 0. Probably like this:

C#

if (this.dgv_Add_job_card.CurrentRow.Cells[4].Value == DBNull.Value || (int)this.dgv_Add_job_card.CurrentRow.Cells[4].Value == 0)

("Probably" because I don't know your intention here.)

Replace the cast (int) by the actual type of that column if it's not int. You know the column types, no need to use Convert.ToXXX if you can just cast it.

If you don't want it to "be able to be DBNull" but just 0 instead you have to change your database-table-column to be non-nullable and when inserting into that table, insert 0 instead of null.

object cannot be cast from dbnull to other types. c#

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