Question

I’m having some troubles with ASP MVC error handling.

On a form that a user tries to connect to a device. If the uses input an invalid device name, it’s pretty straightforward to tell the user the name is invalid.

I’m implementing IEnumerable<RuleViolation> GetRulesViolations() on all my data classes. The RuleViolation class has two fields: PropertyName and ErrorMessage and if I get an error on submit I just call the GetRulesViolations method and set the errors on the ModelState:

catch {
     foreach (var issue in device.GetRulesViolations()) {
          ModelState.AddModelError(issue.PropertyName, issue.ErrorMessage);
     }
     return View();
}

and with some background asp mvc magic the error appears on the view in the ValidationMessage placeholder for the model.Name:

@using (Html.BeginForm()) {
    @Html.ValidationSummary(true)
    <fieldset>

        <div class="editor-label">
            @Html.LabelFor(model => model.Name)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.Name)
            @Html.ValidationMessageFor(model => model.Name)
        </div>

        <p>
            <input type="submit" value="Connect" />
        </p>
    </fieldset>
}

Now the problem:

If the error i’m getting is something like “Could not connect to the device” that’s not a problem related to the Name field. It’s a message that should appear above the form because it’s related to the whole form.

Is there a straightforward way to set this like ModelState.AddError(“error message”) without telling the key so it would apply to the whole form or should I create an Error hidden property on the Data classes and place a validation message for that property above the form?

Answer 1

Yes, empty field name, like this :

ModelState.AddModelError("", issue.ErrorMessage);