Question

我正在尝试将asp.net DataPager控件扩展为具有预定义模板的自定义控件。这是所需的输出

enter image description here

问题：

当我第一次加载包含自定义DataPager的页面时，我SelectMethod的{{1}}被调用了3次。
当我尝试使用DataPager加载另一页数据时，会调用SelectMethod两次。
当我尝试使用Next / Previous按钮或DropDownList加载另一页数据时，页面不会更改。我运行了一些调试，发现它没有将正确的值传递给SelectMethod的StartRowIndexParameter（它每次调用方法时都传递0）。

以下是我的自定义控件的代码。

ObjectDataSource

这就是我的页面：

public class DataPagerDDL : DataPager
{
    protected override void RenderContents(HtmlTextWriter writer)
    {
        //add custom template
        TemplatePagerField templateField = new TemplatePagerField();
        templateField.PagerTemplate = new CustomTemplate();
        Fields.Add(templateField);

        //add previous/next page template
        NextPreviousPagerField nextPreviousField = new NextPreviousPagerField();            
        nextPreviousField.ShowFirstPageButton = false;
        nextPreviousField.ShowLastPageButton = false;
        nextPreviousField.PreviousPageText = "<<";
        nextPreviousField.NextPageText = ">>";
        Fields.Add(nextPreviousField);

        base.RenderContents(writer);
    }

    public void cmbPage_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList cmbPage = (DropDownList)sender;
        this.SetPageProperties(cmbPage.SelectedIndex * MaximumRows, MaximumRows, true);
    }
}

public class CustomTemplate : ITemplate
{
    /// <summary>
    /// Insert an instance of text and controls into the specified container.
    /// </summary>
    public void InstantiateIn(Control container)
    {
        DataPagerFieldItem caller = (DataPagerFieldItem)container;
        DataPagerDDL pager = (DataPagerDDL)caller.Parent;
        int totalPages = pager.TotalRowCount / pager.MaximumRows;
        if (pager.TotalRowCount % pager.MaximumRows > 0) totalPages += 1;
        int currentPage = (pager.StartRowIndex / pager.MaximumRows) + 1;

        DropDownList cmbPage = new DropDownList();
        cmbPage.ID = "cmbPage";
        cmbPage.AutoPostBack = true;
        cmbPage.SelectedIndexChanged += new EventHandler(pager.cmbPage_SelectedIndexChanged);
        for (int i = 1; i <= totalPages; i++)
        {
            ListItem item = new ListItem(i.ToString(), i.ToString());
            if (i == currentPage) item.Selected = true;
            cmbPage.Items.Add(item);
        }

        pager.Controls.Add(new LiteralControl("Page "));
        pager.Controls.Add(cmbPage);
        pager.Controls.Add(new LiteralControl(" of " + totalPages.ToString() + " pages | "));
    }
}

如何使我的自定义DataPager按预期工作？提前致谢！：）

Answer 1

我怀疑您在页面生命周期中太晚创建了分页器字段。尝试从Init类的DataPagerDDL事件创建它们。

此外，您的CustomTemplate应该将控件添加到container，而不是pager。

public class DataPagerDDL : DataPager
{
    protected override void OnInit(EventArgs e)
    {
        CreateDefaultPagerFields();
        base.OnInit(e);
    }

    protected virtual void CreateDefaultPagerFields()
    {
        //add custom template
        TemplatePagerField templateField = new TemplatePagerField();
        templateField.PagerTemplate = new CustomTemplate();
        Fields.Add(templateField);

        //add previous/next page template
        NextPreviousPagerField nextPreviousField = new NextPreviousPagerField();            
        nextPreviousField.ShowFirstPageButton = false;
        nextPreviousField.ShowLastPageButton = false;
        nextPreviousField.PreviousPageText = "<<";
        nextPreviousField.NextPageText = ">>";
        Fields.Add(nextPreviousField);
    }

    public void cmbPage_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList cmbPage = (DropDownList)sender;
        SetPageProperties(cmbPage.SelectedIndex * MaximumRows, MaximumRows, true);
    }
}

public class CustomTemplate : ITemplate
{
    public void InstantiateIn(Control container)
    {
        DataPagerFieldItem caller = (DataPagerFieldItem)container;
        DataPagerDDL pager = (DataPagerDDL)caller.Parent;
        int totalPages = pager.TotalRowCount / pager.MaximumRows;
        if (pager.TotalRowCount % pager.MaximumRows > 0) totalPages += 1;
        int currentPage = (pager.StartRowIndex / pager.MaximumRows) + 1;

        DropDownList cmbPage = new DropDownList();
        cmbPage.ID = "cmbPage";
        cmbPage.AutoPostBack = true;
        cmbPage.SelectedIndexChanged += pager.cmbPage_SelectedIndexChanged;

        for (int i = 1; i <= totalPages; i++)
        {
            ListItem item = new ListItem(i.ToString(), i.ToString());
            if (i == currentPage) item.Selected = true;
            cmbPage.Items.Add(item);
        }

        container.Controls.Add(new LiteralControl("Page "));
        container.Controls.Add(cmbPage);
        container.Controls.Add(new LiteralControl(" of " + totalPages + " pages | "));
    }
}

自定义DataPager的问题

1 个答案: