Asp.Net Core Razor display an error message from if...else

I have a button triggering OnPost action

"PTWIssue" asp-route-idPTWNo="@Model.PTWNo" type="submit" class="btn btn-link text-info font-weight-bolder mt-2 mb-2" style="font-size:20px;" data-toggle="tooltip" data-placement="top" title="Issue the Permit to Work and send to Receiver">Issue Permit To Work

On OnPost I have a check for string. I want to verify that there is no status "Awaiting" and then continue with OnPost. If the check fail, I want a simple message "Error on check" and the process to not continue. I have the following

var checkIsoCert = await (from a in _context.IsoCerts.Where(s => s.PTWNo == idPTWNo)
join b in _context.IsoDetails on a.IdIC equals b.IdIC into TempData1
from c in TempData1
select new { c.IsStatus }).ToListAsync();
string myString = "Awaiting";
var matchingvalues = checkIsoCert.Where(x => x.IsStatus.Equals(myString));
if(matchingvalues == null)
{
var ptwStatus = _context.PTWContents.First(s => s.PTWNo == idPTWNo);
ptwStatus.PTWStatus = "Issued";
await _context.SaveChangesAsync();
return RedirectToPage("PTWForm", "PTWNoId", new { ptwNoId = idPTWNo });
}
else
{
//show an error message such as -You have not complete IsoCert-
}

What I need is to display the message on error. How do I do that on Razor pages?

don't use script

use bootstrap alert , it looks good.

Also in your method , don't use int to store data , other wise it will never be null , by default int has 0 when it has nothing , if you can't use string then use nullable "int ?"

@if (Model.Error==0)
{
class="alert alert-danger" role="alert">
This is a danger alert—check it out!

Forget about old school, I will have the error message displayed at the top of the page, it looks better than popup. Thank you Sachin

It works as alert, highlighting the error, agree, but I am old school, I would like to have it as a popup and for some reasons, jquery modal popup is not working on if else

I have a pop up with

@if (Model.Error == null)
{
"text/javascript">
var message = "Not all Isolation steps are implemented";
if (message)
alert(message);
}

but it doesn't look too good.

any other ideeas?

OK, got it figuered out by

int error = PTWIsoDetails.Count(x => x.IsStatus.Equals(myString));
Error = error.ToString();

and

@if(Model.Error == null)
{
This is an error
}

but now I think a popup twill look better to show the message, most probably a jquery

in page model create one more property

like public string Error {get;set;}

set it on method and use it like normal model property in razor.

Ok, the error is not related to the message, was different source and fixed. However, I still can't show the message

When I use

string myString = "Awaiting";
var matchingvalues = checkIsoCert.Where(x => x.IsStatus.Equals(myString));
if (matchingvalues == null)
{
var ptwStatus = _context.PTWContents.First(s => s.PTWNo == idPTWNo);
ptwStatus.PTWStatus = "Issued";
await _context.SaveChangesAsync();
return RedirectToPage("PTWForm", "PTWNoId", new { ptwNoId = idPTWNo });
}
else
{
ViewData["MyString"] = "You havn't completed IsoCert";
}
return Page();

and

class="col-12 d-flex justify-content-center">
"PTWIssue" asp-route-idPTWNo="@Model.PTWNo" type="submit" class="btn btn-link text-info font-weight-bolder mt-2 mb-2" style="font-size:20px;" data-toggle="tooltip" data-placement="top" title="Issue the Permit to Work and send to Receiver">Issue Permit To Work

also test with viewdata , it should work

ViewData["MyString"] = "Error Message"; // in Page model

@ViewData["MyString"] // in razor

check this

https://www.learnrazorpages.com/razor-pages/viewdata

this ViewBag has to be a model and it is not

obviously you can use sir

give it a try

But Sachin, can I use ViewBag in Razor pages? This is only for MVC

simply use viewbag sir

if(matchingvalues == null)
{
var ptwStatus = _context.PTWContents.First(s => s.PTWNo == idPTWNo);
ptwStatus.PTWStatus = "Issued";
await _context.SaveChangesAsync();
return RedirectToPage("PTWForm", "PTWNoId", new { ptwNoId = idPTWNo });
}
else
{
ViewBag.ErrorMessage="You havn't completed IsoCert";
}
// in Razor page
@ViewBag.ErrorMessage

I can'y implement your solution because my check doesn't work as intended. Let try to work arround and update later

yes sir return error message or any variable with value and check in razor page with if block .

if(condition){
//your code
}
else{
return view ("YourView",new{error="yes"})
}

So you are trying to say that in else statement I just add the error text? And it will be shown in browser? That simple?

My variable is list type, how do I get this into model? Please give an example

You can return view in else part with a new variable or model property then check in your razor page if that property has value which you pass from here then show error message like below .

@if(MyVar=="error")
{
<b>This is your error messageb>
}

18 Replies

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Sachin Singh5y ago
Accepted answer
don't use script
use bootstrap alert , it looks good.
Also in your method , don't use int to store data , other wise it will never be null , by default int has 0 when it has nothing , if you can't use string then use nullable "int ?"
@if (Model.Error==0)
    {
        class="alert alert-danger" role="alert">
  This is a danger alert—check it out!
}