将ContextMenuStrips添加到多个TabPages上的多个DataGridViews

Question

I am trying to load multiple DataTables into DataGridViews in separate tabpages of a TabControl, the DataTables are stored in a Dictionary which is in turn stored in a DataObject class.

I can get everything displaying correctly but when I try to add loop through the Datagridview Header to add a contextmenustrip, for some reason I can get it to work for the first DataGridView but subsequent DataGridViews do not have the context menu applied? I have tried adding a print statentment just before the foreach loop and the DataGridView gets a column count of zero…so im guessing that's why the foreach loop isn't doing anything…but all the data is still displayed correctly in the dataGridViews in their respective tabs…any help in pointing out what I'm missing would be greatly appreciated.

Regards Amarino

Code given below

List<ImportObject> lImportObjects = new List<ImportObject>();

private void loadImportFilesToScreen(List<ImportObject> lImportObjects)
{
    foreach (ImportObject lImportObject in lImportObjects) {
        DisplayImportFiles(lImportObject);
    }
}

public void DisplayImportFiles(ImportObject pImportObject)
{
    string lTabName="";
    //load DataGridView with DataTable
    /*
    foreach (KeyValuePair<string, DataTable> lDT in pImportObject.DataTableDictionary)
    {
        lTabName = DisplayTabsInApp(pImportObject.FileName + "_" + lDT.Key, lDT.Key);
        LoadDatatableIntoGrid(lDT.Value, lTabName);
    }
    */
    for (int i = 0; i < pImportObject.DataTableDictionary.Count; i++)
    {
        KeyValuePair<string, DataTable> lItem = pImportObject.DataTableDictionary.ElementAt(i);
        string lKey = lItem.Key;
        DataTable lDT = lItem.Value;
        lTabName = DisplayTabs(pImportObject.FileName + "_" + lKey, lKey);
        LoadDatatableIntoGrid(lDT, lTabName);
        lDT = null;
    }
}

public string DisplayTabs(string pTabName, string pSheetName)
{
    // Create a new Tab Page for this file. Set heading, set name.
    TabPage lTabPage_NewFile = new TabPage();
    lTabPage_NewFile.Text = pTabName;
    lTabPage_NewFile.Name = "TAB_PAGE_" + pTabName;
    tabControl_ImportFiles.TabPages.Add(lTabPage_NewFile);
    return lTabPage_NewFile.Name;
}

public void LoadDatatableIntoGrid(DataTable pDataTable, string pTabName) {
    DataGridView lDGV = new DataGridView();
    lDGV.RowHeadersWidthSizeMode = DataGridViewRowHeadersWidthSizeMode.EnableResizing;
    lDGV.RowHeadersVisible = false;

    BindingSource BindingSource1 = new BindingSource(); //create new data binding source
    BindingSource1.DataSource = pDataTable;             //SetData source
    lDGV.DataSource = BindingSource1;
    lDGV.RowHeadersVisible = true;

    tabControl_ImportFiles.TabPages[pTabName].Controls.Add(lDGV);
    //DataGridView lDGV = tabControl_ImportFiles.TabPages[pTabName].Controls[0] as DataGridView;
    PrintToConsoleInARD("DataGridView Column Count: " + lDGV.Columns.Count.ToString()); 
    bool runOnce = true; 
    foreach (DataGridViewColumn lDGVColumn in lDGV.Columns) {
        lDGVColumn.HeaderCell.ContextMenuStrip = lCMS_ColumnHeaders;
    }
    lDGV.Dock = DockStyle.Fill;
    lDGV.VirtualMode = true;
    BindingSource1 = null;
    lDGV = null;
}

Answer 1

I am confident the reason for this is because the “tab page” is not displayed. As the trace is described inside the LoadDatatableIntoGrid method… if you put a breakpoint at the line…

tabControl_ImportFiles.TabPages[pTabName].Controls.Add(lDGV);

Add a watch to the variable lDGV.Columns.Count … will show that IDGV has zero (0) columns. Execute the line above and magically, the grid IDGV has columns. This appears correct since this is the first “tab page” and it is the active (displayed) tab page. Point being… if you do not add the grid to a “Active/Shown/Displayed” tab page most UI code will be ignored. This is why the next time around; the grid will be empty because the grid is added to a non “active/shown/displayed” tab page.

A simple solution is to simply “Show” the tab page before you add the grid to it. This appears to fix the issue you describe. Add the line below before the line above…

tabControl_ImportFiles.TabPages[pTabName].Show();

Hope this helps.