Problem Displaying Bootstrap Modal in ASP.NET Core Razor Page - asp.net-core

Question

I'm new to ASP.NET Core and trying to figure out how to display a Bootrstap modal based on a string property of the underlying page Model (Model.Message). I've tried several different things and nothing is working. Below is a sample Bootrstap modal I found on the Bootstrap website. I can get the modal to display with a button, but that's not the functionality I am looking for.
<!-- Modal -->
<div class="modal fade" id="UserDialog" data-bs-backdrop="static" data-bs-keyboard="false" tabindex="-1" aria-labelledby="staticBackdropLabel" aria-hidden="true">
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<h5 class="modal-title" id="staticBackdropLabel">Modal title</h5>
<button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button>
</div>
<div class="modal-body">
...
</div>
<div class="modal-footer">
<button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
<button type="button" class="btn btn-primary">Understood</button>
</div>
</div>
</div>
</div>
EDIT: Added code to my scripts section at the bottom of the page and a new JavaScript function in an external .js file.
Here's my scripts section on the Razor page
#section scripts
{
<script>
$(document).ready(function () {
ShowModalDlg();
var message = '#Model.Message';
if (message != "") {
ShowModalDlg();
}
});
</script>
}
Here's the new JavaScript function in my external file
function ShowModalDlg()
{
$("#UserDialog").modal("show");
}
The ShowModalDlg() function does get called when it is supposed to, but the bootstrap modal is not showing. The button I added to test "showing" the modal still works. I also added (although not shown here) a temporary call to alert("I'm here!") inside of the ShowModalDlg() function and the alert shows perfectly. I did just check the Chrome debug console and I am getting an error that seems to indicate I am loading jquery twice. That error message is:
"$(...).modal is not a function"
So it looks like I need to figure out where that's happening.
I have the following in my _Layout.cshtml page:
<script src="https://code.jquery.com/jquery-1.12.4.js"></script>
<script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"></script>
<script src="https://cdn.jsdelivr.net/npm/bootstrap#5.0.2/dist/js/bootstrap.min.js" integrity="sha384-cVKIPhGWiC2Al4u+LWgxfKTRIcfu0JTxR+EQDz/bgldoEyl4H0zUF0QKbrJ0EcQF" crossorigin="anonymous"></script>

Answer 1

If I understand you, this kind of approach might solve your problem. We define a ShowModal variable sent from the controller as a javascript variable, then we trigger the modal by checking the value of this variable.
EDIT: We expect 'show' string as showModal variable from controller.
<script>
var showModal = '#Model.showModal';
if(showModal == 'show'){
$("#exampleModal").modal("show");
}
</script>
If you use it this way it will work. You can check it here.
<script src="https://cdn.jsdelivr.net/npm/jquery#3.6.0/dist/jquery.min.js"></script>
<script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"></script> <!-- You may not really need this. -->
<!-- Bootstrap 5 (https://getbootstrap.com/docs/5.0/getting-started/download/) -->
<link href="https://cdn.jsdelivr.net/npm/bootstrap#5.0.2/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-EVSTQN3/azprG1Anm3QDgpJLIm9Nao0Yz1ztcQTwFspd3yD65VohhpuuCOmLASjC" crossorigin="anonymous">
<script src="https://cdn.jsdelivr.net/npm/bootstrap#5.0.2/dist/js/bootstrap.bundle.min.js" integrity="sha384-MrcW6ZMFYlzcLA8Nl+NtUVF0sA7MsXsP1UyJoMp4YLEuNSfAP+JcXn/tWtIaxVXM" crossorigin="anonymous"></script>

Answer 2

I fixed the problem by combining the answer above with the following:
$(window).load(function ()
{
var message = '#Model.Message';
if (message != "") {
ShowModalDlg();
}
});
I should not have had that code inside of document ready, which is why it wasn't working and also causing the error message.