Question

我正在尝试使用C＃/ LINQ（CodeBehind）和JavaScript（在.aspx中）开发代码，该代码将测试是否已经存在添加到数据库的值。我的目标是避免系统错误消息，暂停处理，并显示一个警告，指示尝试添加的值是重复值。似乎我正在使用的代码首先触发JavaScript（即在我的LINQ查询检查重复之前）。因此，我无法准确读取LINQ查询。 tbxChannel包含要添加到数据库的值。任何帮助将非常感谢。我正在使用VS 2010，我的代码如下：

LINQ / C＃：

var getChannel = (from c in db.Channel
                  where c.Channel1 == tbxChannel.Text
                  select new { c.Channel1 }).ToList();

if (getChannel.Count > 0)
{
    string tbxDupChannel = getChannel[0].Channel1;
    return;
}

JavaScript的：

if (document.getElementById("<% = tbxDupChannel.ClientID %>").value.length > 0)
{
    var dupChannel = document.getElementById("<% = tbxDupChannel.ClientID %>").value;

    window.alert("Update Aborted... " + dupChannel +
    " is already on the database and cannot be added a second time.");
    return;
}

Answer 1

尝试这样的事情

LINQ / C＃：

// Make DupChannel a public property
public string DupChannel { get; set; }

public void Page_Load(object sender, EventArgs e) 
{
var getChannel = (from c in db.Channel
                  where c.Channel1 == tbxChannel.Text
                  select new { c.Channel1 }).ToList();

if (getChannel.Count > 0)
{
    DupChannel = getChannel[0].Channel1;
    return;
}

JavaScript的：

var dupChannel = '<%= DupChannel %>';
if (dupChannel.length > 0)
{


    window.alert("Update Aborted... " + dupChannel +
    " is already on the database and cannot be added a second time.");
    return;
}

Answer 2

我采用了不同的方法，并通过将JavaScript Alert嵌入我的CodeBehind来解决我的问题：

if (getChannel.Count > 0)
{
    string dupChannel = getChannel[0].Channel1;

    Response.Write(@"<script language='javascript'>alert('Update Aborted... \n \nChannel " + dupChannel + " is already on the database and cannot be added a second time.');</script>");

   tbxChannel.Text = "";

   tbxChannel.Focus();

   return;
}

根据LINQ查询

2 个答案: