Related
I'm trying to write a custom validator that works on the client side that validates that all checkboxes have been ticked.
Here's the declaration on the model:
[DeclarationsAccepted(ErrorMessage = "You must tick all declarations")]
public IList<DeclarationQuestion> DeclarationQuestions { get; set; }
And here's the attribute:
public class DeclarationsAccepted : ValidationAttribute, IClientValidatable
{
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
var questions = value as IList<DeclarationQuestion>;
if (questions != null && questions.All(c => c.Answer))
{
return ValidationResult.Success;
}
return new ValidationResult("You must accepted all declarations to continue");
}
public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
{
var modelClientValidationRule = new ModelClientValidationRule
{
ValidationType = "declarationsaccepted",
ErrorMessage = FormatErrorMessage(metadata.DisplayName)
};
yield return modelClientValidationRule;
}
}
So far so good, works server side.
For the client I'm wiring this up as follows:
jQuery.validator.addMethod('declarationsaccepted', function (value, element, params) {
//Implement logic here to check all boxes are ticked
console.log(value);
return false;
}, '');
jQuery.validator.unobtrusive.adapters.add('declarationsaccepted', {}, function (options) {
options.rules['declarationsaccepted'] = true;
options.messages['declarationsaccepted'] = options.message;
});
I'm displaying the checkboxes like this:
#{ var questionIndex = 0; }
#foreach (var question in Model.DeclarationQuestions)
{
#Html.CheckBoxFor(model => Model.DeclarationQuestions[questionIndex].Answer, new { id = "DeclarationQuestions" + questionIndex})
questionIndex++;
}
And then displaying the validation message using this:
#Html.ValidationMessageFor(c => c.DeclarationQuestions)
When I submit the form the message is displayed but only after a post back to the server. Is there any way to get this to work on the client side?
The reason you will not get client side validation is because the html helpers generate data-val-* attributes for controls associated with properties. jquery.validate.unobtrusive reads those attributes when the form is parsed and using rules, displays an error message in the appropriate element generated by ValidationMessageFor() associated with that control (it does this by matching up the id attributes of the elements - the error message is generated in a span with <span for="TheIdOfTheAssociatedControl" ...>).
You don't (and cant) generate a control for property DeclarationQuestions (only for properties of each item in DeclarationQuestions so there is nothing that can be matched up.
You could handle this by including your own error message placeholder and intercepting the .submit event
html (add css to style #conditions-error as display:none;)
<span id="delarations-error" class="field-validation-error">
<span>You must accept all declarations to continue.</span>
</span>
Script
var declarationsError = $('#delarations-error');
$('form').submit(function() {
var isValid = $('.yourCheckBoxClass').not(':checked') == 0;
if(!isValid) {
declarationsError.show(); // display error message
return false; // prevent submit
}
});
$('.yourCheckBoxClass').change(function() {
if($(this).is(':checked')) {
declarationsError.hide(); // hide error message
}
});
Side note: You loop for generating the checkboxes should be
for (int i = 0; i < Model.DeclarationQuestions.Count; i++)
{
#Html.CheckBoxFor(m => m.DeclarationQuestions[i].Answer, new { id = "DeclarationQuestions" + i})
}
I need to validate 3 or more input fields (required at lest one). For example I have Email, Fax, Phone.
I require at least ONE to be filled in. I need both server and client 'unobtrusive validation'. please help. I looked into "Compare" method and tried modifying it but no luck. please help.
thanks
You could write a custom attribute:
public class AtLeastOneRequiredAttribute : ValidationAttribute, IClientValidatable
{
private readonly string[] _properties;
public AtLeastOneRequiredAttribute(params string[] properties)
{
_properties = properties;
}
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
if (_properties == null || _properties.Length < 1)
{
return null;
}
foreach (var property in _properties)
{
var propertyInfo = validationContext.ObjectType.GetProperty(property);
if (propertyInfo == null)
{
return new ValidationResult(string.Format("unknown property {0}", property));
}
var propertyValue = propertyInfo.GetValue(validationContext.ObjectInstance, null);
if (propertyValue is string && !string.IsNullOrEmpty(propertyValue as string))
{
return null;
}
if (propertyValue != null)
{
return null;
}
}
return new ValidationResult(FormatErrorMessage(validationContext.DisplayName));
}
public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
{
var rule = new ModelClientValidationRule
{
ErrorMessage = ErrorMessage,
ValidationType = "atleastonerequired"
};
rule.ValidationParameters["properties"] = string.Join(",", _properties);
yield return rule;
}
}
which could be used to decorate one of your view model properties (the one you want to get highlighted if validation fails):
public class MyViewModel
{
[AtLeastOneRequired("Email", "Fax", "Phone", ErrorMessage = "At least Email, Fax or Phone is required")]
public string Email { get; set; }
public string Fax { get; set; }
public string Phone { get; set; }
}
and then a simple controller:
public class HomeController : Controller
{
public ActionResult Index()
{
var model = new MyViewModel();
return View(model);
}
[HttpPost]
public ActionResult Index(MyViewModel model)
{
return View(model);
}
}
Rendering the following view which will take care of defining the custom client side validator adapter:
#model MyViewModel
<script src="#Url.Content("~/Scripts/jquery.validate.js")" type="text/javascript"></script>
<script src="#Url.Content("~/Scripts/jquery.validate.unobtrusive.js")" type="text/javascript"></script>
<script type="text/javascript">
jQuery.validator.unobtrusive.adapters.add(
'atleastonerequired', ['properties'], function (options) {
options.rules['atleastonerequired'] = options.params;
options.messages['atleastonerequired'] = options.message;
}
);
jQuery.validator.addMethod('atleastonerequired', function (value, element, params) {
var properties = params.properties.split(',');
var values = $.map(properties, function (property, index) {
var val = $('#' + property).val();
return val != '' ? val : null;
});
return values.length > 0;
}, '');
</script>
#using (Html.BeginForm())
{
#Html.ValidationSummary(false)
<div>
#Html.LabelFor(x => x.Email)
#Html.EditorFor(x => x.Email)
</div>
<div>
#Html.LabelFor(x => x.Fax)
#Html.EditorFor(x => x.Fax)
</div>
<div>
#Html.LabelFor(x => x.Phone)
#Html.EditorFor(x => x.Phone)
</div>
<input type="submit" value="OK" />
}
Of course the custom adapter and validator rule should be externalized into a separate javascript file to avoid mixing script with markup.
I spent more than 36 hours why the code did not work for me.. At the end , I found out that in my case , I was not supposed to use the property names in this line of code
[AtLeastOneRequired("Email", "Fax", "Phone", ErrorMessage = "At least Email, Fax or Phone is required")]
But I had to use the HTMl element Ids in place of the property names and it worked like magic.
Posting this here if it might help somebody.
Since you are using MVC 3, take a look at great video Brad Wilson had on mvcConf. There's everything you need to create client + server Unobtrusive Validation
#Darin Dimitrov 's solution is probably the standard of creating a custom validation attribute that works with unobtrusive validation. However, using custom validation attributes for unobtrusive validation have some disadvantages such as:
The custom validation attribute is only attached to one properties, so client validation will not work if there's a change event on the other two inputs.
The error message works fine with ValidationSummary, but if you want to display 1 error message for the whole group (which I think is the norm), it would be nearly impossible.
To avoid the first problem, we can add custom validation attribute to each element in the group, which will cause another problem: we have to validate all elements of the group, instead of stopping at the first invalid group element. And of course, the second problem - separate error messages for each element - still remains.
There's another way to handle client side validation of group of inputs, using groups setting in jquery validator (https://jqueryvalidation.org/validate/#groups). The only problem (and a big one) is that unobtrusive validation doesn't support jquery validation's groups by default, so we have to customize a little bit.
Although this answer is hardly "unobtrusive", in my opinion, it is worth trying to get rid of unnecessary complication of code, if your final goal is to validate a group of inputs while using Microsoft's unobtrusive validator library.
First, because groups settings of default jquery validator is not available in jquery unobtrusive validator, we have to override unobtrusive settings (ref. How can I customize the unobtrusive validation in ASP.NET MVC 3 to match my style?)
$("form").on('submit', function () {
var form = this;
var validator = $(this).data("validator");
if (validator.settings && !validator.settings.submitHandler) {
$.extend(true, validator.settings.rules, validationSettings.rules);
$.extend(true, validator.settings.groups, validationSettings.groups);
initGroups(validator);
var fnErrorReplacement = validator.settings.errorPlacement;
validator.settings.errorPlacement = function (error, element) {
validationSettings.errorPlacement(error, element, fnErrorReplacement, form);
}
validator.settings.submitHandler = formSubmitHandler;
}
});
function formSubmitHandler(form) {
form.submit();
}
After that, override unobtrusive validator's groups, rules and errorPlacement settings.
var validationSettings = {
groups: {
checkboxgroup: "Email Fax Phone"
},
rules: {
Email: {
required: function () {
return validateCheckboxGroup(["#Email", "#Fax", "#Phone"]);
}
},
Fax: {
required: function () {
return validateCheckboxGroup(["#Email", "#Fax", "#Phone"]);
}
},
Phone: {
required: function () {
return validateCheckboxGroup(["#Email", "#Fax", "#Phone"]);
}
}
}
,
errorPlacement: function (error, element, fnUnobtrusive, form) {
switch (element.attr("name")) {
case "Email":
case "Fax":
case "Phone":
onGroupError(error, "CheckBoxGroup", form);
break;
default:
fnUnobtrusive(error, element);
break;
}
}
}
function validateCheckboxGroup(names) {
var result = true;
$.each(names, function (index, value) {
if ($(value).is(":checked")) {
result = false;
}
});
return result;
}
Because unobtrusive validator does not implement groups setting of jquery validator, we need to reuse two functions from the two libraries to: (1).split group names (reusing code from jquery validator) and (2) append error element without remove 'input-validation-error' class (reusing function onError from unobtrusive library).
function initGroups(validators) {
validators.groups = {};
$.each(validators.settings.groups,
function (key, value) {
if (typeof value === "string") {
value = value.split(/\s/);
}
$.each(value,
function (index, name) {
validators.groups[name] = key;
});
});
}
function onGroupError(error, inputElementName, form) {
var container = $(form).find("[data-valmsg-for='" + inputElementName + "']"),
replaceAttrValue = container.attr("data-valmsg-replace"),
replace = replaceAttrValue ? $.parseJSON(replaceAttrValue) !== false : null;
container.removeClass("field-validation-valid").addClass("field-validation-error");
error.data("unobtrusiveContainer", container);
if (replace) {
container.empty();
error.appendTo(container);
}
else {
error.hide();
}
}
Finally, use HtmlExtensions.ValidationMessage to create error span of the checkbox group.
#Html.ValidationMessage("CheckBoxGroup", new { #class = "text-danger" })
The keeping of "input-validation-error" class is necessary, so that jquery validator will validate all 3 elements (Email, Phone, Fax) of checkbox group as a whole, instead of validating one by one. The unobtrusive validation library remove this class by default on function onError, so we have to customize this as shown in function onGroupError above.
I am using ASP.NET MVC 2 Beta. I can create a wizard like workflow using Steven Sanderson's technique (in his book Pro ASP.NET MVC Framework) except using Session instead of hidden form fields to preserve the data across requests. I can go back and forth between pages and maintain the values in a TextBox without any issue when my model is not a collection. An example would be a simple Person model:
public class Person
{
public string Name { get; set; }
public int Age { get; set; }
public string Email { get; set; }
}
But I am unable to get this to work when I pass around an IEnumerable. In my view I am trying to run through the Model and generate a TextBox for Name and Email for each Person in the list. I can generate the form fine and I can submit the form with my values and go to Step2. But when I click the Back button in Step2 it takes me back to Step1 with an empty form. None of the fields that I previously populated are there. There must be something I am missing. Can somebody help me out?
Here is my View:
<% using (Html.BeginForm()) { %>
<% int index = 0;
foreach (var person in Model) { %>
<fieldset>
<%= Html.Hidden("persons.index", index.ToString())%>
<div>Name: <%= Html.TextBox("persons[" + index.ToString() + "].Name")%></div>
<div>Email: <%= Html.TextBox("persons[" + index.ToString() + "].Email")%></div>
</fieldset>
<% index++;
} %>
<p><input type="submit" name="btnNext" value="Next >>" /></p>
<% } %>
And here is my controller:
public class PersonListController : Controller
{
public IEnumerable<Person> persons;
protected override void OnActionExecuting(ActionExecutingContext filterContext)
{
persons = (Session["persons"]
?? TempData["persons"]
?? new List<Person>()) as List<Person>;
// I've tried this with and without the prefix.
TryUpdateModel(persons, "persons");
}
protected override void OnResultExecuted(ResultExecutedContext filterContext)
{
Session["persons"] = persons;
if (filterContext.Result is RedirectToRouteResult)
TempData["persons"] = persons;
}
public ActionResult Step1(string btnBack, string btnNext)
{
if (btnNext != null)
return RedirectToAction("Step2");
// Setup some fake data
var personsList = new List<Person>
{
new Person { Name = "Jared", Email = "test#email.com", },
new Person { Name = "John", Email = "test2#email.com" }
};
// Populate the model with fake data the first time
// the action method is called only. This is to simulate
// pulling some data in from a DB.
if (persons == null || persons.Count() == 0)
persons = personsList;
return View(persons);
}
// Step2 is just a page that provides a back button to Step1
public ActionResult Step2(string btnBack, string btnNext)
{
if (btnBack != null)
return RedirectToAction("Step1");
return View(persons);
}
}
As far as I can tell, this is not supported in ASP.NET MVC 2 Beta, nor is it supported in ASP.NET MVC 2 RC. I dug through the MVC source code and it looks like Dictionaries are supported but not Models that are IEnumerable<> (or that contain nested IEnumerable objects) and it's inheritors like IList<>.
The issue is in the ViewDataDictionary class. Particularly, the GetPropertyValue method only provides a way to retrieve property values from dictionary properties (by calling GetIndexedPropertyValue) or simple properties by using the PropertyDescriptor.GetValue method to pull out the value.
To fix this, I created a GetCollectionPropertyValue method that handles Models that are collections (and even Models that contain nested collections). I am pasting the code here for reference. Note: I don't make any claims about elegance - in fact all the string parsing is pretty ugly, but it seems to be working. Here is the method:
// Can be used to pull out values from Models with collections and nested collections.
// E.g. Persons[0].Phones[3].AreaCode
private static ViewDataInfo GetCollectionPropertyValue(object indexableObject, string key)
{
Type enumerableType = TypeHelpers.ExtractGenericInterface(indexableObject.GetType(), typeof(IEnumerable<>));
if (enumerableType != null)
{
IList listOfModelElements = (IList)indexableObject;
int firstOpenBracketPosition = key.IndexOf('[');
int firstCloseBracketPosition = key.IndexOf(']');
string firstIndexString = key.Substring(firstOpenBracketPosition + 1, firstCloseBracketPosition - firstOpenBracketPosition - 1);
int firstIndex = 0;
bool canParse = int.TryParse(firstIndexString, out firstIndex);
object element = null;
// if the index was numeric we should be able to grab the element from the list
if (canParse)
element = listOfModelElements[firstIndex];
if (element != null)
{
int firstDotPosition = key.IndexOf('.');
int nextOpenBracketPosition = key.IndexOf('[', firstCloseBracketPosition);
PropertyDescriptor descriptor = TypeDescriptor.GetProperties(element).Find(key.Substring(firstDotPosition + 1), true);
// If the Model has nested collections, we need to keep digging recursively
if (nextOpenBracketPosition >= 0)
{
string nextObjectName = key.Substring(firstDotPosition+1, nextOpenBracketPosition-firstDotPosition-1);
string nextKey = key.Substring(firstDotPosition + 1);
PropertyInfo property = element.GetType().GetProperty(nextObjectName);
object nestedCollection = property.GetValue(element,null);
// Recursively pull out the nested value
return GetCollectionPropertyValue(nestedCollection, nextKey);
}
else
{
return new ViewDataInfo(() => descriptor.GetValue(element))
{
Container = indexableObject,
PropertyDescriptor = descriptor
};
}
}
}
return null;
}
And here is the modified GetPropertyValue method which calls the new method:
private static ViewDataInfo GetPropertyValue(object container, string propertyName) {
// This method handles one "segment" of a complex property expression
// First, we try to evaluate the property based on its indexer
ViewDataInfo value = GetIndexedPropertyValue(container, propertyName);
if (value != null) {
return value;
}
// If the indexer didn't return anything useful, continue...
// If the container is a ViewDataDictionary then treat its Model property
// as the container instead of the ViewDataDictionary itself.
ViewDataDictionary vdd = container as ViewDataDictionary;
if (vdd != null) {
container = vdd.Model;
}
// Second, we try to evaluate the property based on the assumption
// that it is a collection of some sort (e.g. IList<>, IEnumerable<>)
value = GetCollectionPropertyValue(container, propertyName);
if (value != null)
{
return value;
}
// If the container is null, we're out of options
if (container == null) {
return null;
}
// Third, we try to use PropertyDescriptors and treat the expression as a property name
PropertyDescriptor descriptor = TypeDescriptor.GetProperties(container).Find(propertyName, true);
if (descriptor == null) {
return null;
}
return new ViewDataInfo(() => descriptor.GetValue(container)) {
Container = container,
PropertyDescriptor = descriptor
};
}
Again, this is in the ViewDataDictionary.cs file in ASP.NET MVC 2 RC. Should I create a new issue to track this on the MVC codeplex site?
I'm using ValidationMessage control in MVC. When validating each property, it may have more than one error message to show, but the ValidationMessage only displays the first error message in the list.
Here is an example:
ModelState["Key"] = new ModelState();
ModelState["Key"].Errors.Add("Error 1");
ModelState["Key"].Errors.Add("Error 2");
and in the html I have: <%= Html.ValidationMessage("Key")%>
which displays: "Error 1"
I want to see all error messages on the page which will be "Error 1 Error 2"
Any idea how to do it?
I had exactly the same problem, so I created an extension method for HtmlHelper as replacement for the MVC ValidationMessage method.
The benefit of this over ValidationSummary method is that it displays error message per field so you can place it right next to each field (same as ValidationMessage method).
public static string AllValidationMessage(this HtmlHelper helper, string modelName)
{
StringBuilder builder = new StringBuilder();
TagBuilder ulTag = new TagBuilder("ul");
ulTag.AddCssClass("u-error-list");
builder.Append(ulTag.ToString(TagRenderMode.StartTag));
if (helper.ViewData.ModelState.ContainsKey(modelName) &&
helper.ViewData.ModelState[modelName].Errors.Count > 0)
{
foreach (var err in helper.ViewData.ModelState[modelName].Errors)
{
TagBuilder liTag = new TagBuilder("li") { InnerHtml = HttpUtility.HtmlEncode(err.ErrorMessage) };
liTag.AddCssClass("u-error-item");
builder.Append(liTag.ToString());
}
}
builder.Append(ulTag.ToString(TagRenderMode.EndTag));
var msgSpan = helper.ValidationMessage(modelName, "{placeholder}");
if (msgSpan == null)
return string.Empty;
return msgSpan.ToHtmlString().Replace("{placeholder}", builder.ToString());
}
public static string AllValidationMessageFor<TModel, TProperty>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TProperty>> expression)
{
return HtmlHelperExtensions.AllValidationMessage(helper, ExpressionHelper.GetExpressionText(expression));
}
Edit: added AllValidationMessageFor method
Edit: added a null check on msgSpan
With just out-of-the-box MVC, you'll have to add a ValidationSummary:
<%= Html.ValidationSummary() %>
That will show all ModelErrors.
Based on the solutions presented here and in How to display multiple validation errors with #Html.ValidationMessageFor?, I created my own multiline validation message for a property. It behaves somewhat like ValidationSummary but can be used per field. I use it present a validation message for a collection field of a model. This allows me to present a summary message for the collection and only the collection.
public static MvcHtmlString MultilineValidationMessageFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, object htmlAttributes = null)
{
var propertyName = ExpressionHelper.GetExpressionText(expression);
var modelState = htmlHelper.ViewData.ModelState;
// If we have multiple (server-side) validation errors, collect and present them.
if (modelState.ContainsKey(propertyName) && modelState[propertyName].Errors.Count > 1)
{
var msgs = new StringBuilder();
foreach (ModelError error in modelState[propertyName].Errors)
{
msgs.AppendLine(error.ErrorMessage + "<br />");
}
// Return standard ValidationMessageFor, overriding the message with our concatenated list of messages.
var msgSpan = htmlHelper.ValidationMessageFor(expression, "{0}", htmlAttributes as IDictionary<string, object> ?? htmlAttributes);
var msgDiv = msgSpan.ToHtmlString().Replace("span", "div");
return new MvcHtmlString(string.Format(msgDiv, msgs.ToString()));
}
// Revert to default behaviour.
return htmlHelper.ValidationMessageFor(expression, null, htmlAttributes as IDictionary<string, object> ?? htmlAttributes);
}
A more straight to the point approach:
Controller:
ModelState.AddModelError("other", "error 1");
ModelState.AddModelError("other", "error 2");
ModelState.AddModelError("other", "error 3");
View:
<ul>
#foreach (var error in Html.ViewData.ModelState["other"].Errors)
{
<li>#error.ErrorMessage</li>
}
</ul>
As ModelState follows a dictionary pattern for errors, it seems ultimately we need to concatenate all the errors into the single ModelState key:
ModelState["Key"].Errors.Add("Error 1. " + "Error 2");
If you use the IValidatableObject convention to perform custom validations, you can convert the validation result failures to ModelState entries as follows:
var resultsGroupedByMembers = validationResults
.SelectMany(_ => _.MemberNames.Select(
x => new {MemberName = x ?? "",
Error = _.ErrorMessage}))
.GroupBy(_ => _.MemberName);
foreach (var member in resultsGroupedByMembers)
{
ModelState.AddModelError(
member.Key,
string.Join(". ", member.Select(_ => _.Error)));
}
The cross join is needed noting there may be more than one MemberName per Validation Result. Unbound results are bound to "" and should be available to the ValidationSummary.
Also in your Controller Action you can check the
ModelState.IsValid
and if its false, just return the View and the ValidationSumary will be populated.
I want to get all the error messages out of the modelState without knowing the key values. Looping through to grab all the error messages that the ModelState contains.
How can I do this?
Using LINQ:
IEnumerable<ModelError> allErrors = ModelState.Values.SelectMany(v => v.Errors);
foreach (ModelState modelState in ViewData.ModelState.Values) {
foreach (ModelError error in modelState.Errors) {
DoSomethingWith(error);
}
}
See also How do I get the collection of Model State Errors in ASP.NET MVC?.
Building on the LINQ verison, if you want to join all the error messages into one string:
string messages = string.Join("; ", ModelState.Values
.SelectMany(x => x.Errors)
.Select(x => x.ErrorMessage));
I was able to do this using a little LINQ,
public static List<string> GetErrorListFromModelState
(ModelStateDictionary modelState)
{
var query = from state in modelState.Values
from error in state.Errors
select error.ErrorMessage;
var errorList = query.ToList();
return errorList;
}
The above method returns a list of validation errors.
Further Reading :
How to read all errors from ModelState in ASP.NET MVC
During debugging I find it useful to put a table at the bottom of each of my pages to show all ModelState errors.
<table class="model-state">
#foreach (var item in ViewContext.ViewData.ModelState)
{
if (item.Value.Errors.Any())
{
<tr>
<td><b>#item.Key</b></td>
<td>#((item.Value == null || item.Value.Value == null) ? "<null>" : item.Value.Value.RawValue)</td>
<td>#(string.Join("; ", item.Value.Errors.Select(x => x.ErrorMessage)))</td>
</tr>
}
}
</table>
<style>
table.model-state
{
border-color: #600;
border-width: 0 0 1px 1px;
border-style: solid;
border-collapse: collapse;
font-size: .8em;
font-family: arial;
}
table.model-state td
{
border-color: #600;
border-width: 1px 1px 0 0;
border-style: solid;
margin: 0;
padding: .25em .75em;
background-color: #FFC;
}
</style>
As I discovered having followed the advice in the answers given so far, you can get exceptions occuring without error messages being set, so to catch all problems you really need to get both the ErrorMessage and the Exception.
String messages = String.Join(Environment.NewLine, ModelState.Values.SelectMany(v => v.Errors)
.Select( v => v.ErrorMessage + " " + v.Exception));
or as an extension method
public static IEnumerable<String> GetErrors(this ModelStateDictionary modelState)
{
return modelState.Values.SelectMany(v => v.Errors)
.Select( v => v.ErrorMessage + " " + v.Exception).ToList();
}
In case anyone wants to return the Name of the Model property for binding the error message in a strongly typed view.
List<ErrorResult> Errors = new List<ErrorResult>();
foreach (KeyValuePair<string, ModelState> modelStateDD in ViewData.ModelState)
{
string key = modelStateDD.Key;
ModelState modelState = modelStateDD.Value;
foreach (ModelError error in modelState.Errors)
{
ErrorResult er = new ErrorResult();
er.ErrorMessage = error.ErrorMessage;
er.Field = key;
Errors.Add(er);
}
}
This way you can actually tie the error in with the field that threw the error.
Outputting just the Error messages themselves wasn't sufficient for me, but this did the trick.
var modelQuery = (from kvp in ModelState
let field = kvp.Key
let state = kvp.Value
where state.Errors.Count > 0
let val = state.Value?.AttemptedValue ?? "[NULL]"
let errors = string.Join(";", state.Errors.Select(err => err.ErrorMessage))
select string.Format("{0}:[{1}] (ERRORS: {2})", field, val, errors));
Trace.WriteLine(string.Join(Environment.NewLine, modelQuery));
This code snippet is useful too and give you a List that contains of Error Messges.
var errors = ModelState.Values.SelectMany(x => x.Errors.Select(c => c.ErrorMessage)).ToList();
For just in case someone need it i made and use the following static class in my projects
Usage example:
if (!ModelState.IsValid)
{
var errors = ModelState.GetModelErrors();
return Json(new { errors });
}
Usings:
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.Mvc;
using WebGrease.Css.Extensions;
Class:
public static class ModelStateErrorHandler
{
/// <summary>
/// Returns a Key/Value pair with all the errors in the model
/// according to the data annotation properties.
/// </summary>
/// <param name="errDictionary"></param>
/// <returns>
/// Key: Name of the property
/// Value: The error message returned from data annotation
/// </returns>
public static Dictionary<string, string> GetModelErrors(this ModelStateDictionary errDictionary)
{
var errors = new Dictionary<string, string>();
errDictionary.Where(k => k.Value.Errors.Count > 0).ForEach(i =>
{
var er = string.Join(", ", i.Value.Errors.Select(e => e.ErrorMessage).ToArray());
errors.Add(i.Key, er);
});
return errors;
}
public static string StringifyModelErrors(this ModelStateDictionary errDictionary)
{
var errorsBuilder = new StringBuilder();
var errors = errDictionary.GetModelErrors();
errors.ForEach(key => errorsBuilder.AppendFormat("{0}: {1} -", key.Key,key.Value));
return errorsBuilder.ToString();
}
}
Anybody looking for asp.net core 3.1. Slightly updated than the above answer. I found that this is what [ApiController] returns
Dictionary<string, List<string>> errors = new Dictionary<string, List<string>>();
foreach (KeyValuePair<string, ModelStateEntry> kvp in ViewData.ModelState)
{
string key = kvp.Key;
ModelStateEntry entry = kvp.Value;
if (entry.Errors.Count > 0)
{
List<string> errorList = new List<string>();
foreach (ModelError error in entry.Errors)
{
errorList.Add(error.ErrorMessage);
}
errors[key] = errorList;
}
}
return new JsonResult(new {Errors = errors});
And this works too:
var query = from state in ModelState.Values
from error in state.Errors
select error.ErrorMessage;
var errors = query.ToArray(); // ToList() and so on...
Useful for passing array of error messages to View, perhaps via Json:
messageArray = this.ViewData.ModelState.Values.SelectMany(modelState => modelState.Errors, (modelState, error) => error.ErrorMessage).ToArray();
This is expanding upon the answer from #Dunc . See xml doc comments
// ReSharper disable CheckNamespace
using System.Linq;
using System.Web.Mvc;
public static class Debugg
{
/// <summary>
/// This class is for debugging ModelState errors either in the quick watch
/// window or the immediate window.
/// When the model state contains dozens and dozens of properties,
/// it is impossible to inspect why a model state is invalid.
/// This method will pull up the errors
/// </summary>
/// <param name="modelState">modelState</param>
/// <returns></returns>
public static ModelError[] It(ModelStateDictionary modelState)
{
var errors = modelState.Values.SelectMany(x => x.Errors).ToArray();
return errors;
}
}
In addition, ModelState.Values.ErrorMessage may be empty, but ModelState.Values.Exception.Message may indicate an error.
<div class="text-danger" style="direction:rtl" asp-validation-summary="All"></div>
simply use asp-validation-summary Tag Helper
For AJAX Request better solution:
public IActionResult Demo(DemoInfo formData)
{
if (!ModelState.IsValid)
{
IEnumerable<object> formErrors = ModelState.Select((s) => new {
fieldName = s.Key,
fieldValue = s.Value.RawValue,
fieldMessage = s.Value.Errors.FirstOrDefault()?.ErrorMessage
});
return Json(new { formValid = 0, formErrors });
}
return Json(new { formValid = 1 });
}
Response format will be:
{"formValid":0,
"formErrors":[{
"fieldName":"name of field from object",
"fieldValue":"value from browser",
"fieldMessage":null /*Error message from model annotations if field is valid the value will be null */
}]
}
For more details about Func<> check this page : Func<TSource,Int32,TResult>)
var x = new Dictionary<string,string>();
for (var b = 0; b < ViewData.ModelState.Values.Count(); b++)
{
if (ViewData.ModelState.Values.ElementAt(b).Errors.Count() > 0)
x.Add(ViewData.ModelState.Keys.ElementAt(b), String.Join(",", ViewData
.ModelState.Values.ElementAt(b).Errors.Select(c => c.ErrorMessage)));
}
get error with Field Name and Error Message
var errors = new List<ErrorDto>();
foreach (KeyValuePair<string, ModelStateEntry> kvp in context.ModelState)
{
if (kvp.Value.Errors.Count > 0)
{
errors.Add(new ErrorDto()
{
FieldName = kvp.Key,
ErrorMessage = string.Join(",", kvp.Value.Errors.Select(v => v.ErrorMessage))
});
}
}
Error Model
public class ErrorDto
{
public string FieldName { get; set; }
public string ErrorMessage { get; set; }
}
In your implementation you are missing static Class, this should be.
if (!ModelState.IsValid)
{
var errors = ModelStateErrorHandler.GetModelErrors(this.ModelState);
return Json(new { errors });
}
rather
if (!ModelState.IsValid)
{
var errors = ModelState.GetModelErrors();
return Json(new { errors });
}
var result = string.Join(',',ModelState.Values.SelectMany(v => v.Errors).Select(a=>a.ErrorMessage));