Object Reference Not Set error

Question

When I select the datagrid1,it shows an error as

object reference not set

Please help me to solve. I am new in wpf.

 private void dataGrid1_SelectedCellsChanged(object sender, SelectedCellsChangedEventArgs e)
        {
            if (this.dataGrid1.SelectedItems == null || this.dataGrid1.SelectedItems.Count <= 0) return;
            this.db = new DbAccess();
            string str = this.dataGrid1.SelectedCells[0].Item.ToString();
            DataTable dataTable =
                this.db.DataTab(
                    @"SELECT [SeriesNo], [SeriesDescription], [Instances] 
                      FROM   [Roamani].[dbo].[View_Study123]
                      WHERE[StudyUID] = '" + str +"'");
            string[] strArray = new string[4];
            if (dataTable.Rows.Count > 0)
            {
                strArray[0] = str;
                strArray[1] = dataTable.Rows[0]["SeriesNo"].ToString();
                strArray[2] = dataTable.Rows[0]["SeriesDescription"].ToString();
                strArray[3] = dataTable.Rows[0]["Instances"].ToString();
            }
        }

@user3592261:it's means your Rows is null and you are trying to check count — Dhaval Patel, May 06 '14 at 05:57
first check your query, check it returns the data from databse — Dhaval Patel, May 06 '14 at 05:58
when am debug,the first cell value seen in debug section,but datatable as null — user3592261, May 06 '14 at 06:00
this is am using "SELECT [SeriesNo], [Instances] FROM [Roamani].[dbo].[View_Study123] WHERE [StudyUID]='" + str + "'" — user3592261, May 06 '14 at 06:28
public DataTable DataTab(string query){ DataTable dataTable = new DataTable(); try{if (this.DbConn.State == ConnectionState.Closed){ this.createConn();} else { this.DbConn.Close(); this.DbAdapter.Dispose(); this.createConn();} if (this.DbConn.State == ConnectionState.Open) { this.DbAdapter = new SqlDataAdapter(query, this.DbConn); this.DbAdapter.Fill(dataTable); }return dataTable;} catch { return (DataTable)nul } } — user3592261, May 06 '14 at 06:44

score 0 · Answer 1 · answered May 06 '14 at 07:01

Replace your method with below mentioned method and change the conncetion string.

 public DataTable DataTab(string query)
    {
        string conncetion = "Data Source=(local);Initial Catalog=Temp;User ID=sa;Password=sa123*";
        SqlConnection cnn = new SqlConnection(conncetion);

        string str = string.Empty;
        SqlCommand cmd = new SqlCommand();
        cmd.CommandType = CommandType.Text;
        cmd.Connection = cnn;
        if (cnn.State == ConnectionState.Closed)
            cnn.Open();

        DataTable dataTable = new DataTable(); 
        SqlDataAdapter adp = new SqlDataAdapter(query, cnn);
        adp.Fill(dataTable);
        return dataTable;

    }

and still you getting null then try with this query

 @"SELECT [SeriesNo], [SeriesDescription], [Instances] 
                  FROM   [View_Study123].[dbo].[Roamani]
                  WHERE[StudyUID] = '" + str +"'");

here View_study123 is your database name and Romani is your table name

Object Reference Not Set error

1 Answers1