Question

我有一个.aspx应用程序，用户输入一个名称，并将该名称添加到列表中。这最多可以完成五次。当用户单击该按钮时，输入的第一个名称将显示在第一个标签中。当用户输入另一个名称并单击该按钮时，第一个标签保持不变，下一个标签显示新名称，依此类推。我的问题是在PostBack上重置列表。我试图使用ViewState来帮助解决这个问题，但没有成功。非常感谢任何帮助。

编辑：我得到了它的工作，所以谢谢大家的帮助。仍有很大的改进空间，但这是一个很好的起点。

       [Serializable]
    class Recipient
    {
        public string Fname { get; set; }
        public string MInit { get; set; }
        public string Lname { get; set; }
        public string Suffix { get; set; }
    }

    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void btnEnter_Click(object sender, EventArgs e)
    {
        Recipient recipients = new Recipient();

        List<string> FName = (List<string>)ViewState["recipientList"];
        List<string> MInit = (List<string>)ViewState["recipientList"];
        List<string> LName = (List<string>)ViewState["recipientList"];


        if (FName == null && MInit == null && LName == null)
        {
            FName = new List<string>();
            MInit = new List<string>();
            LName = new List<string>();
        }

        recipients.Fname = txtFName.Text;
        recipients.MInit = txtMinit.Text;
        recipients.Lname = txtLName.Text;
        FName.Add(recipients.Fname);
        MInit.Add(recipients.MInit);
        LName.Add(recipients.Lname);
        ViewState["recipientList"] = FName;
        ViewState["recipientList"] = MInit;
        ViewState["recipientList"] = LName;

        if (FName.Count == 1 && MInit.Count == 1 && LName.Count == 1)
        {
            lblFName.Text = FName[0] + " " + MInit[0] + " " + LName[0];
        }

        if (FName.Count == 4 && MInit.Count == 4 && LName.Count == 4)
        {
            lblFName1.Text = FName[1] + " " + MInit[2] + " " + LName[3];
        }

    }

Answer 1

你真的需要一份清单吗？你可以做......

if(lblFName.Text.Equals(String.Empty))
{
    lblFName.Text = value;
}
else if(lblFName1.Text.Equals(String.Empty))
{
    lblFName1.Text = value;
}//and so on...

Answer 2

我不确定收件人类的目的。无论如何，你想在添加收件人之前实例化收件人列表。

enter image description here

<asp:TextBox runat="server" ID="txtFName" /><br />
<asp:Button runat="server" ID="btnEnter" Text="Submit" OnClick="btnEnter_Click" /><br />
<asp:Label runat="server" ID="lblFName" /><br />
<asp:Label runat="server" ID="lblFName1" /><br />
<asp:Label runat="server" ID="lblFName2" /><br />
<asp:Label runat="server" ID="lblFName3" /><br />
<asp:Label runat="server" ID="lblFName4" /><br />

[Serializable]
public class Recipient
{
    public string name { get; set; }
}

public List<Recipient> recipientList
{
    get
    {
        if (ViewState["recipientList"] != null)
            return (List<Recipient>)ViewState["recipientList"];
        return new List<Recipient>();
    }
    set { ViewState["recipientList"] = value; }
}

protected void btnEnter_Click(object sender, EventArgs e)
{
    List<Recipient> recipient = recipientList;
    recipient.Add(new Recipient{ name = txtFName.Text.Trim()});
    recipientList = recipient;

    int count = recipient.Count;

    if (count == 1)
        lblFName.Text = recipientList[0].name;

    if (count > 1)
        lblFName1.Text = recipientList[1].name;

    if (count > 2)
        lblFName2.Text = recipientList[2].name;

    if (count > 3)
        lblFName3.Text = recipientList[3].name;

    if (count > 4)
        lblFName4.Text = recipientList[4].name;
}

Answer 3

如果按下回车按钮后会触发回发。然后，您需要处理重新构建Page_Load中的列表。像这样：

 protected void Page_Load(object sender, EventArgs e)
 {
    if (!IsPostBack)
    {
        recipientList = (List<string>)ViewState["recipientList"];

        //now load the list
    }
  }

列表在PostBack之后保持填充状态

3 个答案: