Tag: c#

Get file path in .net core from wwwroot folder

This is how;

public class HomeController : Controller {
    private IWebHostEnvironment _hostEnvironment;

    public HomeController(IWebHostEnvironment environment) {
        _hostEnvironment = environment;
    }

    [HttpGet]
    public IActionResult Get() {
        string path = Path.Combine(_hostEnvironment.WebRootPath, "Sample.PNG");
        return View();
    }
}

References

https://weblog.west-wind.com/posts/2020/Feb/26/Working-with-IWebHostEnvironment-and-IHostingEnvironment-in-dual-targeted-NET-Core-Projects#out-with-old-in-with-the-new-iwebhostenvironment

Decode JWT Token

Decoding JWT token and return value;

protected string GetCalimValue(string token)
{
   var handler = new JwtSecurityTokenHandler();
   var jsonToken = handler.ReadToken(token);
   var tokenJWT = jsonToken as JwtSecurityToken;
   //var jwtSecurityToken = handler.ReadJwtToken(token);

   var jti = tokenJWT.Claims.First(claim => claim.Type == "jti").Value;
   return jti;
}

Validating and Decoding JWT Token and return value;

protected string ValidateTokenAndGetClaimValue(string token)
{
    string secret = "this is a string used for encrypt and decrypt token";
    var key = Encoding.ASCII.GetBytes(secret);
    var handler = new JwtSecurityTokenHandler();
    var validations = new TokenValidationParameters
    {
        ValidateIssuerSigningKey = true,
        IssuerSigningKey = new SymmetricSecurityKey(key),
        ValidateIssuer = false,
        ValidateAudience = false
    };
    var claims = handler.ValidateToken(token, validations, out var tokenSecure);

    var tokenJWT = tokenSecure as JwtSecurityToken;
    var emailAddress = tokenJWT.Claims.First(claim => claim.Type == "email").Value;
    return emailAddress;
}

We want to keep token inside cookies on a successful token acquisition;

Response.Cookies.Append("X-Access-Token", login.JwToken, new CookieOptions() { HttpOnly = true, SameSite = SameSiteMode.Strict });
Response.Cookies.Append("X-Email", login.Email, new CookieOptions() { HttpOnly = true, SameSite = SameSiteMode.Strict });

References

https://stackoverflow.com/questions/38340078/how-to-decode-jwt-token

https://www.codemag.com/Article/2105051/Implementing-JWT-Authentication-in-ASP.NET-Core-5

Search string array in collection using LINQ

LINQ behavior is that LINQ wouldn’t return null when results are empty rather it will return an empty enumerable. We can check this with .Any() method;

if (!YourResult.Any())

This is a LinqPad example;

var lst = new List<int>() { 1, 2, 3 };
var ans = lst.Where( i => i > 3 );

(ans == null).Dump();  // False
(ans.Count() == 0 ).Dump();  // True

Let’s go through another example where I have this string array to search;
{“dog”,”cat”};

in this string;
“This is a string and may or may not contain a word we are looking for like cat”

string input = "This is a string and may or may not contain a word we are looking for like cat";
List<string> search = new List<string>() { "dog", "cat"};
bool found = input.Split(' ').Any(x => search.Contains(x));

It works like this: the string gets split into an array of words. Then Any checks whether there is an x in this array where search.Contains(x).

Enumerable.Any(TSource) Method (IEnumerable(TSource)) (System.Linq)

Reference

What does linq return when the results are empty

Find all items in list which exist in another list using linq

Hide/Show Div with javascript

To display and hide DIV in html;

<div class="card-body">
   <div id="divMessage">                
        @Html.Raw(@TempData["message"]);
    </div>
    </div>  
    <div> 
       <!--need to hide this form-->         
       <form method="post" asp-antiforgery="true" id="formDiv">
          <div class="card mb-3">
             <h5 class="card-header text-white">
                  Welcome To Div Hide/Display
             </h5>
        </form>
    </div>
</div>

Use this javascript;

@section Scripts
{
  <script>
     $(document).ready(function () {
            //show/hide login sections based on SSO
            divFormSection();
        });

        function divFormSection() {
            var isDivFormVisible = '@TempData["IsDivFormVisible"]';
            if (isDivFormVisible == 'false') {
                //alert(isDivFormVisible);
                $("#formDiv").hide();
            }
        }
     }
    </script>
}

We need to pass parameters from controller in TempData;

TempData["message"] = "Form Hide/Display demo";
TempData["IsDivFormVisible"] = "false";

Use TempData or ViewBag to render HTML

This is a very basic example;

Declare this in a controller.

var fontAwesomeIcon = "<span class=\"fa fa-redo\" style=\"font-size:30px; color: red; margin-bottom: 20px; \">&nbsp;Try again</span>";

TempData["message"] = $"{fontAwesomeIcon} <h5>Something went wrong. Please try again. If problem persist, reach out to your point of contact for additional information</h5>";

And you can use it in your view;

<div class="card-body">
  <div id="divMessage">
     @Html.Raw(@TempData["message"]);
  </div>
</div>