我使用後臺工作器在C#中生成報告,但我收到此錯誤。在C#中生成報告導致錯誤
源代碼如下:
- 我要訪問我的datagridview記錄來訪問它的數據。
- 在我的datagridview中打開一個小窗口,要求用戶輸入日期並生成報告,然後訪問我的datagridview轉換爲數據表寫入XML文件並生成報告。
全局變量
// This is the form where the data lies, I'm accessing it's instance.
Records TR = new Records();
// This is the form where report will be displayed.
TReportDisplay TRD = new TReportDisplay();
// This is the report.
Treport treport1 = new Treport();
private void button1_Click(object sender, EventArgs e)
{
// FIXED HERE - 1
// FIXED - 2 IN THE ANSWER BELOW.
// Accessing my DataGridView Form Instance.
TR = Application.OpenForms.OfType<Records>().ElementAt(0);
treport1.SetDataSource(TR.ds);
TRD.crystalReportViewer2.ReportSource = treport1;
backgroundWorker1.RunWorkerAsync();
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
try
{
TRD.crystalReportViewer2.ReportSource = treport1;
ParameterFieldDefinitions Parameters;
ParameterFieldDefinition Parameter;
ParameterValues Values = new ParameterValues();
ParameterDiscreteValue DiscreteValue = new ParameterDiscreteValue();
DiscreteValue.Value = dateTimePicker1.Text;
Parameters = treport1.DataDefinition.ParameterFields;
Parameter = Parameters["fromdate"];
Values = Parameter.CurrentValues;
Values.Clear();
Values.Add(DiscreteValue);
Parameter.ApplyCurrentValues(Values);
DiscreteValue.Value = dateTimePicker2.Text;
Parameters = treport1.DataDefinition.ParameterFields;
Parameter = Parameters["todate"];
Values = Parameter.CurrentValues;
Values.Add(DiscreteValue);
Parameter.ApplyCurrentValues(Values);
}
}
catch (Exception ex) { MessageBox.Show(ex.Message.ToString(), "Message"); };
}
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
}
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
TRD.ShowDialog();
}
有兩個問題,第一,從一個不同的線程,我得到的答案全部更新進度條,經過後臺工作的另一個電話形式的實例是造成問題,只需將變量放在後臺工作者啓動異步並修復之前。
錯誤真的說明了一切。看看這裏:[鏈接](http://stackoverflow.com/questions/7609839/accessing-a-forms-control-from-a-separate-thread) – parvee