C＃でbackgroundworkerを使用してdatagridviewでデータベースデータを取得する

Question

DataGridviewのデータベースからデータを取得した後、最後のデータが繰り返されますが、datagridviewの最初のデータが欠落しています。 1122逃していると最後のデータPEC-5281が繰り返される：私は、私はファースト・データはこの出力を得た。このリンクhttps://www.mindstick.com/Articles/1148/datagrid-using-backgroundworker-c-sharp

 private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e) 
    { 
     RetriveTableData Obj = (RetriveTableData)e.Argument; 

     string SqlcmdString = "SELECT * from tblBook"; 

     SqlDataReader reader; 
     int i = 1; 
     try 
     { 
      using (SqlConnection conn = new SqlConnection(connectionString)) 
      { 
       Sqlcmd = new SqlCommand(SqlcmdString, conn); 
       conn.Open(); 
       reader = Sqlcmd.ExecuteReader(); 

       if (reader.HasRows) 
       { 
        while (reader.Read()) 
        { 
         //int.Parse(reader["NO_IND"].ToString()); 
         // Obj.EmpId = reader["C_FICH"].ToString(); 
        // Obj.EmpName = reader["C_SITE"].ToString(); 
         Obj.AccessionNo = reader["accessionNo"].ToString(); 
         Obj.Author = reader["author"].ToString(); 

         Thread.Sleep(100); 
         // To Report progress. 
         backgroundWorker1.ReportProgress(i, Obj); 

         if (backgroundWorker1.CancellationPending) 
         { 
          // Set the e.Cancel flag so that the WorkerCompleted event 
          // knows that the process was cancelled. 
          e.Cancel = true; 
          backgroundWorker1.ReportProgress(0); 
          return; 
         } 
         i++; 
        } 
        conn.Close(); 
       } 
      } 
     } 
     catch (Exception ex) 
     { 
      MessageBox.Show(ex.Message); 
     } 
    } 

    public class RetriveTableData 
    { 
     public string AccessionNo; 
     public string Author; 
    } 

    private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e) 
    { 
     if (!backgroundWorker1.CancellationPending) 
     { 
      //Gets the user state that is sent as part of ReportProgress() Method from DoWork Event 
      RetriveTableData Obj = (RetriveTableData)e.UserState; 
      //Add the data to the dataGridView1 
      dataGridView1.Rows.Add(Obj.AccessionNo.ToString(), Obj.Author.ToString()); 
      progressBar1.Value = e.ProgressPercentage; 
      label1.Text = "Processing row.. " + e.ProgressPercentage.ToString() + " of " + TotalRecords; 
     } 

    } 
    private int GetTotalRecords() 
    { 
     SqlConnection con; 
     SqlCommand cmd; 
     try 
     { 
      using (con = new SqlConnection(connectionString)) 
      { 
       cmd = new SqlCommand("SELECT COUNT(*) FROM tblBook", con); 
       con.Open(); 
       TotalRecords = int.Parse(cmd.ExecuteScalar().ToString()); 
       con.Close(); 
      } 
     } 
     catch (Exception ex) 
     { 
      MessageBox.Show(ex.Message); 
     } 
     return TotalRecords; 
    } 

    private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) 
    { 

     if (e.Cancelled) 
     { 
      label1.Text = "Cancelled by User Intentionally..."; 
     progressBar1.Value = 0; 
     } 
     // Check to see if an error occurred in the background process. 
     else if (e.Error != null) 
     { 
      label1.Text = e.Error.Message; 
     } 
     else 
     { 
      // BackGround Task Completed with out Error 
      label1.Text = " All Records Loaded..."; 
     } 
    } 

    private void button1_Click(object sender, EventArgs e) 
    { 
     // statusStrip1.Visible = true; 
     // toolStripStatusLabel1.Visible = true; 


     dataGridView1.ColumnCount = 2; 
     dataGridView1.Columns[0].Name = "Access No."; 
     dataGridView1.Columns[0].Width = 150; 
     dataGridView1.Columns[1].Width = 150; 
     dataGridView1.RowHeadersWidth = 21; 
     dataGridView1.ColumnHeadersHeightSizeMode = DataGridViewColumnHeadersHeightSizeMode.EnableResizing; 
     dataGridView1.ColumnHeadersHeight = 23; 
     dataGridView1.Columns[1].Name = "Author"; 


     progressBar1.Maximum = GetTotalRecords(); 

     if (!backgroundWorker1.IsBusy) 
     { 
      RetriveTableData TObj = new RetriveTableData(); 
      dataGridView1.Rows.Clear(); 
      // Start the BackGround Thread to Execute 
      backgroundWorker1.RunWorkerAsync(TObj); 
      // btStart.Enabled = false; 
      //btCancel.Enabled = true; 
     } 

    } 

に従ってください。私の低レベルのために私は画像を投稿できなかったので、あなたは出力を見ることができるリンクを置く。

https://krishnas.com.np/2.PNG

Answer 1

は、あなたはそれがより明確とBackgroundWorker

によって作成された余分なスレッドのない少しの入札を行うことができますナドその後、行ごとにオブジェクトのコレクションを作成 async-awaitで DataGridView

のデータソースとしてそのコレクションを使用する必要があります

private async Task<IEnumerable<RetriveTableData>> GetDataAsync() 
{ 
    var query = "SELECT * from tblBook"; 
    using (var connection = new SqlConnection(connectionString)) 
    using (var command = new SqlCommand(query, connection)) 
    { 
     await connection.OpenAsync(); 
     using (var reader = command.ExecuteReaderAsync()) 
     { 
      var data = new List<RetriveTableData>(); 
      while(await reader.ReadAsync()) 
      { 
       var temp = new RetriveTableData 
       { 
        EmpId = reader["C_FICH"].ToString(); 
        EmpName = reader["C_SITE"].ToString(); 
        AccessionNo = reader["accessionNo"].ToString(); 
        Obj.Author = reader["author"].ToString(); 
       }; 

       data.Add(temp); 
      } 

      return data; 
     } 
    } 
} 

たとえば、Form.Loadイベントハンドラでは、データを読み込むことができます。

private async void Form_Load(object sender, EventArgs e) 
{ 
    dataGridView1.DataSource = await GetDataAsync(); 
}