在列表框中未选择任何项目时禁用asp按钮(Disabling asp button when no items selected in list box)

在列表框中未选择任何项目时禁用asp按钮(Disabling asp button when no items selected in list box)

如果在列表框中没有选择任何项目，我希望我的按钮被禁用。 我有按钮Enable设置为false。 选择某个项目时，该按钮会启用true，但是，在启用该按钮后，如果未选择任何列表项，则不会禁用该按钮。

代码背后：

protected void Button2_Click(object sender, EventArgs e) { List<ListItem> itemsRemove = new List<ListItem>(); foreach (ListItem listItem in ListBox1.Items) { if (listItem.Selected) itemsRemove.Add(listItem); } foreach (ListItem listItem in itemsRemove) { ListBox1.Items.Remove(listItem); } } protected void ListBox1_SelectedIndexChanged(object sender, EventArgs e) { foreach (ListItem item in ListBox1.Items) { if (item.Selected) { Button2.Enabled = true; } } }

I would like my button to be disabled if no items are are selected in the Listbox. I have the button Enable set to false. When an item is selected the button does enable true, however, after the button is enabled it will not disable when there no list items selected.

Code behind:

protected void Button2_Click(object sender, EventArgs e) { List<ListItem> itemsRemove = new List<ListItem>(); foreach (ListItem listItem in ListBox1.Items) { if (listItem.Selected) itemsRemove.Add(listItem); } foreach (ListItem listItem in itemsRemove) { ListBox1.Items.Remove(listItem); } } protected void ListBox1_SelectedIndexChanged(object sender, EventArgs e) { foreach (ListItem item in ListBox1.Items) { if (item.Selected) { Button2.Enabled = true; } } }

最满意答案

尝试这个：

protected void ListBox1_SelectedIndexChanged(object sender, EventArgs e) { Button2.Enabled = false; foreach (ListItem item in ListBox1.Items) { if (item.Selected) { Button2.Enabled = true; } } }

但它不是这种功能的最佳解决方案，最好使用一些JavaScript代码来启用/禁用您的按钮。

编辑（最小解决方案）：

protected void ListBox1_SelectedIndexChanged(object sender, EventArgs e) { Button2.Enabled = ListBox1.Items.Any(x => x.Selected); }

Try this:

protected void ListBox1_SelectedIndexChanged(object sender, EventArgs e) { Button2.Enabled = false; foreach (ListItem item in ListBox1.Items) { if (item.Selected) { Button2.Enabled = true; } } }

But it is not the best solution for such functionality, it is better to use some javascript code to enable/disable your button.

EDIT (minimal solution):

protected void ListBox1_SelectedIndexChanged(object sender, EventArgs e) { Button2.Enabled = ListBox1.Items.Any(x => x.Selected); }