Add CSS Class Conditionally - Asp.net

Question

I have gone through some posts with similar question but haven't find any good solution yet.

I am trying to add a css class in a div by checking that if there exists any error or not. Like below

<div class="form-group m-t-20 @((@Html.ValidationMessage("Email") != null && @Html.ValidationMessage("Email").ToString() != "") ? "has-danger has-error" : "")">

But when I do inspect-element then it seems that @Html.ValidationMessage("Email") is never empty (so has-danger has-error is always added) even though there is not validation message for Email, like

@Html.ValidationMessage("Email") translated to <span class="field-validation-valid" data-valmsg-for="Email" data-valmsg-replace="true"></span>

So is there a way to check if certain error is present then add a css class ? Also I would apperciate that I donot need to create new class (.cs file) for this small purpose.

PS: I am using Asp.net MVC. And at back-end I add error like this ModelState.AddModelError("Email", "User already exists");

Why not just use the class names that already are added - field-validation-valid (if its valid) and field-validation-error (if its not) — user3559349
– user3559349, Commented Jun 28, 2017 at 12:03
@StephenMuecke I want to add custom css class to div, my structure is <div class="custom-class"><input /></div>. Does class name matter here ? — Junaid S.
– Junaid S., Commented Jun 28, 2017 at 12:07
What is the purpose? Why not just style the field-validation-error class? — user3559349
– user3559349, Commented Jun 28, 2017 at 12:09

teo van kot · Accepted Answer · 2017-06-28 12:48:29Z

3

If you want to check errors in your model on View you should check ViewData.ModelState property.

Like this:

@if (!ViewData.ModelState.IsValid && ViewData.ModelState["Email"].Errors.Count > 0))
{
   <span>your message<span/>
}

Ternary version:

@((!ViewData.ModelState.IsValid && ViewData.ModelState["Email"].Errors.Count > 0)? "your message": String.Empty)

edited Jun 28, 2017 at 12:48

answered Jun 28, 2017 at 12:06

teo van kot

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8 Comments

Junaid S. Over a year ago

On IsValidField its giving me error

Compiler Error Message: CS1061: 'System.Web.Mvc.ViewDataDictionary<HospitalManagament.Models.SignupModel>' does not contain a definition for 'IsValidField' and no extension method 'IsValidField' accepting a first argument of type 'System.Web.Mvc.ViewDataDictionary<HospitalManagament.Models.SignupModel>' could be found (are you missing a using directive or an assembly reference?)

teo van kot Over a year ago

@Junaid what version of MVC do you use?

Junaid S. Over a year ago

I am using v5.2.3.0.

Junaid S. Over a year ago

I tried your solution, but its still adding has-danger has-error in both cases (error and no-error).

teo van kot Over a year ago

@Junaid and what's exactly inside ViewData.ModelState["Email"] with and withour error? Maby you should just ckeck in on String.Empty?

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