Runtime Error: Object reference not set to an instance of an object. --> please help me

wooi83

int bookID = int.Parse(txtboxSearchbyISBN.Text); dsBookISBN = SearchData.ListBookByISDN(bookID); DataSet dsBookISBN = new DataSet(); Services SearchData = new Services(); DataRow dr; int bookID = int.Parse(txtboxSearchbyISBN.Text); dsBookISBN = SearchData.ListBookByISDN(bookID); try{ dr = dsBookISBN.Tables["Table"].Rows[0]; //<----- i have errors on this line lbltitle.Text= "Book Title :" + dr["bookTitle"].ToString(); lblauthor.Text = "Author :" + dr["bookAuthor"].ToString(); lblisbn.Text= "ISBN :" + dr["bookISBN"].ToString(); lblpubliser.Text= "Publiser :" + dr["bookPublisher"].ToString(); lblyearpublished.Text= "Year Published :" + dr["bookYearPublished"].ToString(); lbldatereceived.Text= "Date Received :" + dr["bookDateReceived"].ToString(); lblcategory.Text= "Category :" + dr["bookCategory"].ToString(); lblloanstatus.Text= "Loan Status :" + dr["bookLoanStatus"].ToString(); ActiveForm = frmSearchResult; } catch(System.IndexOutOfRangeException) { lblError.Visible = true; }

4 Replies

Know the answer? Post it — somebody with the same question will find it here.

wooi8322y ago
it helps... thanks alot!
+1
Andrzej Wegierski22y ago
dsBookISBN is null after searching I think. Check the reason and use if (dsBookISBN!=null && dsBookISBN.Tables.Count >1) instead of if (dsBookISBN.Tables.Count >1)
+1
wooi8322y ago
private void btnSearchbyISBN_Click(object sender, System.EventArgs e) { if(txtboxSearchbyISBN.Text.Length != 0 && int.Parse(txtboxSearchbyISBN.Text) > 0) { bookID = int.Parse(txtboxSearchbyISBN.Text); dsBookISBN = SearchData.ListBookByISDN(bookID); //try{ if (dsBookISBN.Tables.Count >1) <<-- now error in this line { dr = dsBookISBN.Tables["Table"].Rows[0]; lbltitle.Text= "Book Title :" + dr["bookTitle"].ToString(); lblauthor.Text = "Author :" + dr["bookAuthor"].ToString(); lblisbn.Text= "ISBN :" + dr["bookISBN"].ToString(); lblpubliser.Text= "Publiser :" + dr["bookPublisher"].ToString(); lblyearpublished.Text= "Year Published :" + dr["bookYearPublished"].ToString(); lbldatereceived.Text= "Date Received :" + dr["bookDateReceived"].ToString(); lblcategory.Text= "Category :" + dr["bookCategory"].ToString(); lblloanstatus.Text= "Loan Status :" + dr["bookLoanStatus"].ToString(); ActiveForm = this.frmSearchResult; } /* } catch(System.IndexOutOfRangeException) { lblError.Visible = true; }*/ } else { RequiredFieldValidator2.Visible = true; } } public DataSet ListBookByISDN(int bookID) { DataSet myDataset = new DataSet(); SqlParameter[] Param = { new SqlParameter("@bookID", SqlDbType.Int) }; Param[0].Value = bookID; try { if (DC.ListBook("listByBookID", Param, myDataset)== true) { return myDataset; } else { return null; } } catch { return null; } } }
+1
kovan22y ago
change it to if (dsBookISB.Tables.Count >1) dr = dsBookISBN.Tables[0].Rows[0]; //<----- i have errors on this line let me know if that works for u
+1