如何在按钮单击时更改 FooterRow 和列的可见性 - C#

Question

我有一个大约 16 列的 GridView，出于美学原因，我只想显示某些列，但是如果用户想要插入一行（使用页脚行），我需要使其余列可见。

页面加载时：

protected void Page_Load(object sender, EventArgs e)
{
    if (Add_Button.Text != "Cancel")
    {
        GridView1.FooterRow.Visible = false;
        GridView1.Columns[10].Visible = false;
        GridView1.Columns[11].Visible = false;
        GridView1.Columns[12].Visible = false;
        GridView1.Columns[13].Visible = false;
        GridView1.Columns[14].Visible = false;
        GridView1.Columns[15].Visible = false;
        GridView1.Columns[16].Visible = false;
    }
    else
    {
        GridView1.FooterRow.Visible = true;
    }
}

点击按钮后：

protected void Add_Button_Click(object sender, EventArgs e)
{
    if (GridView1.FooterRow.Visible == false)
    {
        GridView1.Columns[8].Visible = true;
        GridView1.Columns[9].Visible = true;
        GridView1.Columns[10].Visible = true;
        GridView1.Columns[11].Visible = true;
        GridView1.Columns[12].Visible = true;
        GridView1.Columns[13].Visible = true;
        GridView1.Columns[14].Visible = true;
        GridView1.FooterRow.Visible = true;
        Add_Button.Text = "Cancel";
        Panel2.Visible = false;
    }
    else
    {                    
        Add_Button.Text = "Add New Record"; 
        GridView1.FooterRow.Visible = false;
    }
}

客户端页脚行的可见性设置为真，额外列的可见性设置为假。我一直在尝试将页脚行的可见性设置为 false，将列的可见性设置为 true 等等，但似乎没有什么能给我想要的结果。

目前，在第一次单击按钮时，额外的行和页脚行可见，而在第二次单击时，应该使它们再次不可见，它只会使页脚行不可见，而不是列。有什么解决方法吗？

Answer 1

问题

由于您的Page_Load 方法中没有if (!this.IsPostBack) 块，因此当您单击Add_Button 时，Page_Load 方法中的所有代码将在执行Add_Button_Click 方法之前执行。

在第二次点击时，Page_Load 会发生以下情况：

protected void Page_Load(object sender, EventArgs e)
{
    if (Add_Button.Text != "Cancel")
    {
        GridView1.FooterRow.Visible = false;
        GridView1.Columns[10].Visible = false;
        GridView1.Columns[11].Visible = false;
        GridView1.Columns[12].Visible = false;
        GridView1.Columns[13].Visible = false;
        GridView1.Columns[14].Visible = false;
        GridView1.Columns[15].Visible = false;
        GridView1.Columns[16].Visible = false;
    }
    else
    {
        // this block is executed because Add_Button.Text is "Cancel",
        // which was the result of the first click
        GridView1.FooterRow.Visible = true;
    }
}

这就是Add_Button_Click 发生的事情：

protected void Add_Button_Click(object sender, EventArgs e)
{
    if (GridView1.FooterRow.Visible == false)
    {
        GridView1.Columns[8].Visible = true;
        GridView1.Columns[9].Visible = true;
        GridView1.Columns[10].Visible = true;
        GridView1.Columns[11].Visible = true;
        GridView1.Columns[12].Visible = true;
        GridView1.Columns[13].Visible = true;
        GridView1.Columns[14].Visible = true;
        GridView1.FooterRow.Visible = true;
        Add_Button.Text = "Cancel";
        Panel2.Visible = false;
    }
    else
    {
        // this block is executed because GridView1.FooterRow.Visible is true,
        // which was the result of Page_Load execution on the second click
        Add_Button.Text = "Add New Record"; 
        GridView1.FooterRow.Visible = false;
    }
}

这就是为什么在第二次点击时列不可见的原因。

解决方案

我假设您当前在Page_Load 方法中拥有的内容应该在页面的第一次加载时执行，因此您需要添加if (!this.IsPostBack) 块，如下所示：

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        if (Add_Button.Text != "Cancel")
        {
            GridView1.FooterRow.Visible = false;
            GridView1.Columns[10].Visible = false;
            GridView1.Columns[11].Visible = false;
            GridView1.Columns[12].Visible = false;
            GridView1.Columns[13].Visible = false;
            GridView1.Columns[14].Visible = false;
            GridView1.Columns[15].Visible = false;
            GridView1.Columns[16].Visible = false;
        }
        else
        {
            GridView1.FooterRow.Visible = true;
        }
    }
}

并改变Add_Button_Click方法如下：

protected void Add_Button_Click(object sender, EventArgs e)
{
    if (GridView1.FooterRow.Visible == false)
    {
        GridView1.Columns[8].Visible = true;
        GridView1.Columns[9].Visible = true;
        GridView1.Columns[10].Visible = true;
        GridView1.Columns[11].Visible = true;
        GridView1.Columns[12].Visible = true;
        GridView1.Columns[13].Visible = true;
        GridView1.Columns[14].Visible = true;
        GridView1.FooterRow.Visible = true;
        Add_Button.Text = "Cancel";
        Panel2.Visible = false;
    }
    else
    {
        GridView1.Columns[8].Visible = false;
        GridView1.Columns[9].Visible = false;
        GridView1.Columns[10].Visible = false;
        GridView1.Columns[11].Visible = false;
        GridView1.Columns[12].Visible = false;
        GridView1.Columns[13].Visible = false;
        GridView1.Columns[14].Visible = false;
        GridView1.FooterRow.Visible = false;
        Add_Button.Text = "Add New Record"; 
    }
}