Insert C# string variable into Javascript alert in ASP.NET code behind

Question

I'm using a Gridview with some text boxes and a drop down box in it. When the user clicks on a row (text box or DDL), I want to pop up a Javascript alert that tells them what the row number is. I can get an event to fire when a user clicks on one of the text boxes, but I can't tell them which row it is inside the alert because I can't seem to figure out how to put a C# variable into a Javascript alert.

Here's what I've tried:

public void gv_instruments_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
       TextBox txtBox1 = (TextBox)e.Row.FindControl("txt_partNumbers");
       if (txtBox1 != null)
       {
           txtBox1.Attributes.Add("onclick", "javascript:alert('Message')"); //works

           Int32 selectedRow = e.Row.RowIndex;//get row index number
           string message = "You've selected row: " + selectedRow.ToString();
           message = "javascript:alert('" + message + "')";

           //txtBox1.Attributes.Add("onclick", message); //doesn't work 

           string title = "title";
           //ScriptManager.RegisterStartupScript(Page, Page.GetType(), 
                title, "alert('" + message + "');", true); //doesn't work

           //ScriptManager.RegisterClientScriptBlock(Page,Page.GetType(), 
                title, "alert('" + message + "');",true); //doesn't work
            }
        }
    }

I've found pages on the internet that use the "javascript:alert('" + message + "')"; construct, but it doesn't work (or at least I can't get it to work). I've been careful with the double quotes & single quotes and I can see what looks like a valid message in the debugger (EG: javascript:alert('You've selected row: 0'), I also thought the apostrophe in "you've" might have been the problem, so I removed that & replaced it with "you have", but that doesn't work either. The only construct that I can get to work is this:

txtBox1.Attributes.Add("onclick", "javascript:alert('Message')");

What am I missing?

This is just bad. You should leave front-end logic to front-end. Why not just add javascript code into your HTML that will listen on table-row clicks and then display the appropriate message? — Stan
– Stan, Commented May 6, 2013 at 21:02

anandd360 · Accepted Answer · 2017-02-26 10:16:48Z

3

just try this

string noofrows = dt.Rows.Count.ToString();
string message = "alert('"+ noofrows +" rows found')";
ScriptManager.RegisterClientScriptBlock((sender as Control), this.GetType(),"alert", message, true);
return;

answered Feb 26, 2017 at 10:16

anandd360

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Comments

Win · Accepted Answer · 2013-05-06 21:30:25Z

If you move your javascript to front end, your code will be a lot cleaner.

Here is an example which displays an alert box if you click on a textbox.

enter image description here

<script type="text/javascript">
    function showMessage(id) {
        alert('You have selected row: ' + id);
    }
</script>        
<asp:GridView runat="server" ID="gv_instruments" 
    OnRowDataBound="gv_instruments_RowDataBound"
    AutoGenerateColumns="False">
    <Columns>
        <asp:BoundField HeaderText="Id" DataField="Id" />
        <asp:BoundField HeaderText="FirstName" DataField="FirstName" />
        <asp:BoundField HeaderText="LastName" DataField="LastName" />
        <asp:TemplateField HeaderText="Click Me">
            <ItemTemplate>
                <asp:TextBox runat="server" ID="txt_partNumbers">
                </asp:TextBox>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

public class User
{
    public int Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        var collection = new List<User>()
            {
                new User {Id = 1, FirstName = "John", LastName = "Doe"},
                new User {Id = 2, FirstName = "Marry", LastName = "Doe"},
                new User {Id = 3, FirstName = "David", LastName = "Newton"},
            };

        gv_instruments.DataSource = collection;
        gv_instruments.DataBind();
    }
}

public void gv_instruments_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        var txtBox1 = (TextBox) e.Row.FindControl("txt_partNumbers");
        if (txtBox1 != null)
        {
            txtBox1.Attributes.Add("onclick", 
              string.Format("showMessage('{0}')", e.Row.RowIndex));
        }
    }
}

thanks for the answer and all the work you went to, I appreciate it. While I've got a working solution, I want to incorporate your methods because I agree they're cleaner. Thanks again and I'll accept your answer once I've done the incorporation.

Steve · Accepted Answer · 2013-05-06 21:01:25Z

1

Probably it doesn't work because the second message contains a single quote.

"You've selected row: "
    ^

Try to write

"You&apos;ve selected row: "

answered May 6, 2013 at 21:01

Steve

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3 Comments

delliottg Over a year ago

Thanks, but as pointed out in the OP, that's not the problem.

Steve Over a year ago

Strange, I am sure that if you leave the single quote it doesn't work because there are many questions here on this case. Could you try with the Unicode \u0027 escape character? See a similar problem in this question

delliottg Over a year ago

thanks for the link & the suggestion. I tried using the unicode string, but I still get nothing when I click on the textbox. So then I tried a simple string in there, & voila, it worked. So, I added the row number to the simple string (just five random alpha characters), and that works as well. So I thought it must be something else in the original string, I eliminated the colon, spaces, etc as culprits. Now I'm using "You have selected row: " + selectedRow.ToString(); which is working. I'm still mystified because I don't see anything that's changed all that much.

Shai Aharoni · Accepted Answer · 2013-05-06 21:03:56Z

0

Your problem occurs beacuse of the apostrophe (') in "You've" . You should escape the apostrophe and use : "You\'ve selected row: "

answered May 6, 2013 at 21:03

Shai Aharoni

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1 Comment

delliottg Over a year ago

Thanks, but as pointed out in the OP, that's not the problem.

OnoSendai · Accepted Answer · 2013-05-06 21:06:50Z

0

You may try populating all buttons with the ItemIndex property at render time, like this:

txtBox1.Attributes.Add(
    "onclick", 
    "javascript:alert('" + e.Item.ItemIndex.ToString() + "')"
    );

At line 8 in your example.

answered May 6, 2013 at 21:06

OnoSendai

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1 Comment

delliottg Over a year ago

Thanks for the suggestion, but this isn't exactly what I need.

rog wool · Accepted Answer · 2024-04-09 02:54:16Z

0

in javascript write a C# string in an alert

@:alert('@name');

answered Apr 9, 2024 at 2:54

rog wool

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