未从C＃函数ASP.Net触发Javascript函数

Question

I am using a asp:Repeater control while trying to develop a screen as shown below: Submit form

When ToolId is entered on the TextChanged Event I am getting value for MaxToolLife stored as double. When an user enter values greater than the stored value for the field ToolLife I need to show Yes/No popup stating "The value entered is greater than existing value. Do you want to proceed?" on button submit or textchanged event. Currently I am using the below code but I am not getting Javascript alert.

protected void btnSubmit_Click(object sender, EventArgs e)
{
    if (Convert.ToDouble(txtToolLifeAchieved.Text) > maxToolLife)
    {
        Page.ClientScript.RegisterStartupScript(Page.GetType(), "Confirm", "javascript:Confirm();", true);

        if (hdnconfirm.Value=="Yes")
        {
            row["Pcs Produced"] = Convert.ToDouble(txtToolLifeAchieved.Text);
        }
        else
        {
            txtToolLifeAchieved.Text = "1";
            txtToolLifeAchieved.Focus();
            return;
        }
    }
    else
    {
        row["Pcs Produced"] = Convert.ToDouble(txtToolLifeAchieved.Text);
    }
}

In place of Page.ClientScript I have also used "Page.ClientScript.RegisterClientScriptBlock" & /ScriptManager.RegisterStartupScript. Nothing is working as of now. I am unable to call the javascript function from code behind. Any immediate response would help a lot.

The confirm() is as shown below:

 function Confirm() { var confirm_value = document.createElement("INPUT"); confirm_value.type = "hidden"; confirm_value.name = "confirm_value"; if (confirm("The data already exists. Do you want to Overwrite data?")) { confirm_value.value = "Yes"; document.getElementById('<%= hdnconfirm.ClientID %>').value = "Yes"; } else { confirm_value.value = "No"; document.getElementById('<%= hdnconfirm.ClientID %>').value = "No"; } document.forms[0].appendChild(confirm_value); } 

Answer 1

So, I will stick to your original code, and this is how your server method should look like:

// This is just to illustrate the limit
private const double MaxToolLife = 100;


protected void btnSubmit_Click(object sender, EventArgs e)
{
    // Check the limit first
    if (Convert.ToDouble(txtToolLifeAchieved.Text) > MaxToolLife)
    {
        // If the hidden field is empty show the confirm
        // By default the hidden field is empty, it means that user just
        // pressed the submit button but not the confirmation dialog
        if (string.IsNullOrWhiteSpace(hdnconfirm.Value))
        {
            ClientScript.RegisterStartupScript(this.GetType(), "Confirm", "Confirm();", true);
            return;
        }

        // If the hidden field is not empty, this postback was made by the confirm
        // So check for the value of the hidden field
        if (hdnconfirm.Value == "Yes")
        {
            // Handle 'Yes'
        }
        else
        {
            // Handle 'No'
        }
    }
    else
    {
        // The limit is not reached
    }
}

I omitted your specific code above. This is how the form looks like:

<form id="form1" runat="server">
    <!-- Hidden field for the confirm result -->
    <asp:HiddenField ID="hdnconfirm" runat="server" />
    <!-- Text box for user input -->
    <asp:TextBox ID="txtToolLifeAchieved" runat="server"></asp:TextBox>
    <!-- Submit button -->
    <asp:Button ID="btnSubmit" runat="server" Text="Submit" OnClick="btnSubmit_Click" />
</form>

Than right before the form tag in your page, place your javascript function, it must be place before the form tag, because calling ClientScript.RegisterStartupScript will append the script at the end of your form tag and that time your Confirm() method be defined. And this is your javascript method:

<script type="text/javascript">
    function Confirm() {
        if (confirm("The data already exists. Do you want to Overwrite data?")) {
            document.getElementById('<%= hdnconfirm.ClientID %>').value = "Yes";
        }
        else {
            document.getElementById('<%= hdnconfirm.ClientID %>').value = "No";
        }

        // Post the form back to server using the '__EVENTTARGET' hidden field
        var form = document.getElementById("form1");

        // Create hidden field
        var input = document.createElement("input");
        input.setAttribute("type", "hidden");
        input.setAttribute("name", "__EVENTTARGET");
        input.setAttribute("id", "__EVENTTARGET");
        input.setAttribute("value", '<%= btnSubmit.ClientID %>');

        // Append input to the form element
        form.appendChild(input);

        // Submit the form
        form.submit();
    } 
</script>

There is no need to create another hidden field for the confirmation result. Instead just right after the confirm you need to create hidden field with name set to __EVENTTARGET , and the value of that hidden field must be the name of the submit button, and than just call submit method on the form. This will case postback to the server, with the hdnconfirm set to Yes or No while your btnSubmit_Click method will be executed.