In C#, constructors cannot be declared as async because they are special methods used for object initialization and cannot be awaited. However, you can use an asynchronous factory method or an initialization method to perform asynchronous operations during object creation. Here’s an example:
public class MyClass
{
private MyClass()
{
// Private constructor to enforce the usage of factory method
}
public static async Task<MyClass> CreateAsync()
{
var instance = new MyClass();
await instance.InitializeAsync();
return instance;
}
private async Task InitializeAsync()
{
// Perform asynchronous initialization tasks here
await Task.Delay(1000); // Example asynchronous operation
}
}
In the above example, the constructor for MyClass is marked as private to enforce the usage of the CreateAsync factory method. The CreateAsync method creates an instance of MyClass, calls the private constructor, and then asynchronously initializes the object by calling the InitializeAsync method. You can perform any necessary asynchronous operations within the InitializeAsync method.
To create an instance of MyClass, you would use the CreateAsync method as follows:
var myObject = await MyClass.CreateAsync();
By using this approach, you can achieve asynchronous behavior during object construction in C#.
Below is a bootstrap fragment to setup a dropdown input with images.
<html>
<head>
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css" rel="stylesheet"
integrity="sha384-EVSTQN3/azprG1Anm3QDgpJLIm9Nao0Yz1ztcQTwFspd3yD65VohhpuuCOmLASjC" crossorigin="anonymous">
<style>
.img-dropdown {
display: inline-block;
vertical-align: middle;
margin-right: 10px;
width: 20px;
height:20px;
}
</style>
</head>
<body>
<div class="container">
<div class="row">
<div class="col">
<div style="float:left">
<div class="dropdown">
<button class="btn btn-secondary" type="button" id="dropdownMenuButton"
data-bs-toggle="dropdown" aria-expanded="false">
<div id="languageButtonText">??</div>
</button>
<ul class="dropdown-menu" aria-labelledby="dropdownMenuButton" id="ulLanguages">
<li>
<a class="dropdown-item" href="#" data-value="DE">
<img src="img/de.svg" alt="Image 1" class="img-dropdown">
German
</a>
</li>
<li>
<a class="dropdown-item" href="#" data-value="FR">
<img src="img/fr.svg" alt="Image 2" class="img-dropdown">
French
</a>
</li>
<li>
<a class="dropdown-item" href="#" data-value="GB">
<img src="img/gb.svg" alt="Image 3" class="img-dropdown">
English
</a>
</li>
<li>
<a class="dropdown-item" href="#" data-value="NL">
<img src="img/nl.svg" alt="Image 4" class="img-dropdown">
Dutch
</a>
</li>
<li>
<a class="dropdown-item" href="#" data-value="Frisian">
<img src="img/frisian.svg" alt="Image 5" class="img-dropdown">
Frisian
</a>
</li>
</ul>
</div>
</div>
<div style="float:left">
<div id="selected-image" style="align-items: center; display:flex;margin-left:5px"></div>
</div>
</div>
</div>
</div>
</body>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.7.0/jquery.min.js"
integrity="sha512-3gJwYpMe3QewGELv8k/BX9vcqhryRdzRMxVfq6ngyWXwo03GFEzjsUm8Q7RZcHPHksttq7/GFoxjCVUjkjvPdw=="
crossorigin="anonymous" referrerpolicy="no-referrer"></script>
<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>
<script>
$(document).ready(function () {
// When a dropdown item is clicked
$('.dropdown-item').click(function () {
var lang = $(this).data('value');
var id = 'Language';
$('#' + id).val(lang);
// Get the image source of the clicked item
var selectedImageSrc = $(this).find('img').attr('src');
// Set the selected image in the div
$('#selected-image').html('<img src="' + selectedImageSrc + '" alt="Selected Image" width="51">');
$("#languageButtonText").html(lang);
});
$("#ulLanguages li a").filter("[data-value=" + "Frisian" + "]").trigger("click");
});
</script>
</html>
To enable syntax highlighting on your ASP.NET site follow the steps below:
In the Shared/_Layout.cshtml add both the prism.js and prism.css file.
In the Index.cshtml view add some code to test it out
<div class="row">
<div class="col line-numbers">
<pre><code class="language-csharp">public class HelloWorld
{
public static void Main(string[] args)
{
Console.WriteLine("Hello, World!");
}
}
</code>
</pre>
</div>
<div class="col">
<pre>
<code class="language-sql">
SELECT * FROM AspNetUsers u
LEFT JOIN AspNetRols on r.Id = u.Id
WHERE ID = 1;
</code>
</pre>
</div>
</div>
The resulting page will look like this
Sometimes you need to know the domain on which your app is running. If you are behind a proxy there is not a straightforward way to determine this.
To get the “real” domain name for your app check the “X-Forwarded-Host” HTTP header and use this as your host name when, for example, sending links in emails to your app.
First step is to get the host name:
public static string GetForwardedHost(HttpRequest Request)
{
string host = Request.Headers["X-Forwarded-Host"];
if (host == null)
{
host = Request.Host.ToString();
}
return host;
}
Next when you assemble a link for in example an email you want so sent use the code below
var host = Utils.GetForwardedHost(Request);
var callbackUrl = Url.Page(
"/Account/ResetPassword",
pageHandler: null,
values: new { area = "Identity", code },
protocol: Request.Scheme, host : host);
this.SendEmail(Input.Email, "Reset Password", $"Please reset your password by <a href='{HtmlEncoder.Default.Encode(callbackUrl)}'>clicking here</a>.");
When you get the error “Unable to connect to web server ‘IIS Express’ you probably try to start the website with a port that is in an excluded port range
Sometimes your ASP.NET tab disappears in the IIS manager. To show this tab again follow the steps below.