c# - 动态生成文本框 asp.net
问题描述
我创建了一个函数来根据从文本框中选择的数量动态创建文本框,另外我正在使用这些文本框来显示来自数据库的数据。但是,当用户从下拉列表中选择了五个,并且已经存在三个文本框时,它不会再添加 2 个文本框,而是添加额外的 5 个文本框。为了添加额外的文本框,我做了什么?
protected void TotalSeal_SelectedIndexChanged(object sender, EventArgs e)
{
populate();
}
public void populate()
{
int count = Convert.ToInt32(TotalSeal.SelectedItem.Value);
for (int i = 0; i < count; i++)
{
if (i < 0)
{
}
else
{
TextBox tx = new TextBox();
tx.MaxLength = 10;
tx.Width = 100;
phSealNum.Controls.Add(tx);
phSealNum.Controls.Add(new LiteralControl(" "));
ControlCache.Add(tx);
}
}
}
更新
public void populate()
{
//ControlCache = new List<Control>();
//phSealNum.Controls.Clear();
int targetCount = Convert.ToInt32(TotalSeal.SelectedItem.Value);
int currentItems = phSealNum.Controls.OfType<TextBox>().Count();
int totalitems = targetCount - currentItems;
if (totalitems <= 7)
{
for (int i = 0; i < totalitems; i++)
{
TextBox tx = new TextBox();
tx.MaxLength = 10;
tx.Width = 100;
phSealNum.Controls.Add(tx);
phSealNum.Controls.Add(new LiteralControl(" "));
ControlCache.Add(tx);
}
}
else
{
lblError.Text = targetCount + " exceeds number of seals";
}
}
解决方案
使用@indrit-kello 逻辑应该是这样的:
protected void TotalSeal_SelectedIndexChanged(object sender, EventArgs e)
{
populate();
}
public void populate()
{
int targetCount = Convert.ToInt32(TotalSeal.SelectedItem.Value);
if(targetCount > 7)
targetCount = 7;
int currentItems = 0;//TODO
for (int i = currentItems; i < targetCount; i++)
{
TextBox tx = new TextBox();
tx.MaxLength = 10;
tx.Width = 100;
phSealNum.Controls.Add(tx);
phSealNum.Controls.Add(new LiteralControl(" "));
ControlCache.Add(tx);
}
}