ASP .Net MVC: Razor view ignores or skips validation ViewBag - asp.net-mvc

Question

I am trying to have validation for my Search option field, which is inside Index.cshtml :
When I enter name it works fine and displays all matching results inside DetailsBySurname.cshtml :
This is DetailsBySurname.cshtml
This Razor view supposed to show Validation Success or Error messages depending on whats inside the ViewBag, but when it redirects from Controller IActionResult to my Razor View with Error Messages inside ViewBag it skips(i think) the block of code with if statement and goes directly to foreach loop which is supposed to be activated only when there are NO Error messages. Then i get this error:
Here is Code for the Razor view DetailsBySurname.cshtml:
#model IEnumerable<codeRed_Capstone.Models.Employee>
#{
ViewData["Title"] = "DetailsBySurname";
Layout = "~/Views/Shared/_Layout.cshtml";
}
#if (ViewBag.Message != null)
{
<p class="alert-#(ViewBag.Error != null ? "danger" : "success")">#(ViewBag.Message)</p>
if (ViewBag.Error != null)
{
<ul>
#foreach (Exception e in ViewBag.Exception.ValidationExceptions)
{
<li class="alert-danger">#(e.Message)</li>
}
</ul>
}
}
<h1>Details</h1>
<div>
<h4>Employee</h4>
<hr />
#foreach (var item in Model)
{
<dl class="row">
<dt class="col-sm-2">
#Html.DisplayNameFor(item => item.FirstName)
</dt>
<dd class="col-sm-10">
#Html.DisplayFor(modelItem => item.FirstName)
</dd>
<dt class="col-sm-2">
#Html.DisplayNameFor(model => item.LastName)
</dt>
<dd class="col-sm-10">
#Html.DisplayFor(modelItem => item.LastName)
</dd>
</dl>
}
</div>
This is block of code from Controller for the IAction result DetailsBySurname:
public async Task<IActionResult> DetailsBySurname(string lastName)
{
if (Request.Query.Count > 0)
{
try
{
ValidationException exception = new ValidationException();
lastName = !string.IsNullOrWhiteSpace(lastName) ? lastName.Trim() : null;
using (CompanyContext context = new CompanyContext())
{
if (string.IsNullOrWhiteSpace(lastName))
{
exception.ValidationExceptions.Add(new Exception("Last Name Not Provided"));
}
// Category ID fails parse.
// Common validation points (5) and (5a).
int n;
bool isNumeric = int.TryParse(lastName, out n);
if (isNumeric)
{
exception.ValidationExceptions.Add(new Exception("ID Not Valid string"));
}
else
{
// Category ID exists.
// Common validation point (7).
if (!context.Employees.Any(x => x.LastName == lastName))
{
exception.ValidationExceptions.Add(new Exception("Last Name Does Not Exist"));
}
}
if (exception.ValidationExceptions.Count > 0)
{
throw exception;
}
}
var employees = _context.Employees.Where(m => m.LastName == lastName);
ViewBag.Message = $"Successfully Found {lastName}!";
return View(employees);
}
// Catch ONLY ValidationException here.
catch (ValidationException e)
{
ViewBag.LastName = lastName;
ViewBag.Message = "There exist problem(s) with your submission, see below.";
ViewBag.Exception = e;
ViewBag.Error = true;
return View(e);
}
}
return View();
}
finally here is code for the search field inside Index.cshtml view:
#model IEnumerable<codeRed_Capstone.Models.Employee>
#{
ViewData["Title"] = "Index";
Layout = "~/Views/Shared/_Layout.cshtml";
}
<nav class="navbar navbar-expand-lg navbar-light bg-light">
<a class="navbar-brand" href="#">Navbar</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav mr-auto">
<li class="nav-item active">
</li>
<li class="nav-item dropdown">
<form action="/Employee/Index" method="get">
<lable for="filter"> Show Laid of Staff</lable>
<input type="checkbox" id="filter" name="filter" value="laidoff" />
<input class="btn btn-outline-success my-2 my-sm-0" type="submit" value="Go!" />
</form>
</li>
</ul>
<form action="/Employee/DetailsByEmail" method="get" class="form-inline my-2 my-lg-0">
<input id="email" name="email" data-val="true" data-val-required="Email is required" class="form-control mr-sm-2" type="search" placeholder="Search by Email" aria-label="Search">
<span class="field-validation-valid" data-valmsg-for="email" data-valmsg-replace="true"></span>
<button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
</form>
<form action="/Employee/DetailsBySurname" method="get" class="form-inline my-2 my-lg-0">
<input id="lastName" name="lastName" data-val="true" data-val-required="Last Name is required" class="form-control mr-sm-2" type="search" placeholder="Search by Last Name" aria-label="Search">
<span class="field-validation-valid" data-valmsg-for="lastName" data-valmsg-replace="true"></span>
<button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
</form>
</div>
</nav>
I watched debugging it works as expected goes all the way till the end, only when it jumps to Razor View it gives me this error that i mentioned above.
I also have Class created to handle all Validation exceptions but its working fine. I'm sure problem is some where here between Controller and Razor view. Or maybe problem somewhere else, i'm new to ASP .Net MVC, any suggestions?

Answer 1

I fixed it with a different validation approach.
For the DetailsBySurname i removed if(ViewBag... and added different if(ViewData... - statement to check if returned result is null then don't run foreach loop). To catch error messages use another if statement #if(!ViewData.ModelState.IsValid) like this:
#model IEnumerable<codeRed_Capstone.Models.Employee>
#{
ViewData["Title"] = "DetailsBySurname";
Layout = "~/Views/Shared/_Layout.cshtml";
}
<h1>Details</h1>
<div>
#if (ViewData.ModelState.IsValid)
{
<h4>Employee</h4>
<hr />
#foreach (var item in Model)
{
<dl class="row">
<dt class="col-sm-2">
#Html.DisplayNameFor(item => item.FirstName)
</dt>
<dd class="col-sm-10">
#Html.DisplayFor(modelItem => item.FirstName)
</dd>
<dt class="col-sm-2">
#Html.DisplayNameFor(item => item.LastName)
</dt>
<dd class="col-sm-10">
#Html.DisplayFor(modelItem => item.LastName)
</dl>
}
}
</div>
<div class="form-row">
<div class="form-group col-md-2">
#if (!ViewData.ModelState.IsValid)
{
<span class="field-validation-error">#ViewData.ModelState["LastName"].Errors[0].ErrorMessage</span>
}
</div>
</div>
Then inside Controller for the IAction result DetailsBySurname I changed validation method to built-in validation which looks something like this:
public async Task<IActionResult> DetailsBySurname(string lastName)
{
lastName = !string.IsNullOrWhiteSpace(lastName) ? lastName.Trim() : null;
if (string.IsNullOrWhiteSpace(lastName))
{
ModelState.AddModelError("LastName", "Last Name not Provided");
//exception.ValidationExceptions.Add(new Exception("Last Name Not Provided"));
}
bool exists;
if (!(exists = _context.Employees.Any(m => m.LastName == lastName)))
{
//return NotFound(new Exception("Email not found"));
ModelState.AddModelError("LastName", "Last Name not found");
}
if (!ModelState.IsValid)
{
return View();
}
else
{
var employee = _context.Employees.Where(m => m.LastName == lastName);
return View(employee);
}
}