Coming from the asp.net background, I really appreciated the concept of 'validationGroup' when adding validation to a page. I've been searching for a corresponding concept within mvc.net and haven't had much luck.
Is this concept available in mvc.net? If not, what alternatives do I have?
Unfortunately no, it doesn't come with anything like that.
I blogged about a workaround a wee while back.
ASP.NET MVC - Validation Summary with 2 Forms & 1 View
The jist of the blog post:
namespace System.Web.Mvc
{
public static class HtmlExtensions
{
public static string ActionValidationSummary(this HtmlHelper html, string action)
{
string currentAction = html.ViewContext.RouteData.Values["action"].ToString();
if (currentAction.ToLower() == action.ToLower())
return html.ValidationSummary();
return string.Empty;
}
}
}
And
<h2>Register</h2>
<%= Html.ActionValidationSummary("Register") %>
<form method="post" id="register-form" action="<%= Html.AttributeEncode(Url.Action("Register")) %>">
... blah ...
</form>
<h2>User Login</h2>
<%= Html.ActionValidationSummary("LogIn") %>
<form method="post" id="login-form" action="<%= Html.AttributeEncode(Url.Action("LogIn")) %>">
... blah ...
</form>
HTHs,
Charles
Expanding on Charlino's answer, and including HtmlAttributes and other ValidationSummary properties:
public static MvcHtmlString ActionValidationSummary(this HtmlHelper html, string action, bool excludePropertyErrors, string message, object htmlAttributes = null)
{
var currentAction = html.ViewContext.RouteData.Values["action"].ToString();
if (currentAction.ToLower() == action.ToLower())
{
return html.ValidationSummary(excludePropertyErrors, message, htmlAttributes);
}
return new MvcHtmlString(string.Empty);
}
Charles's method was the only approach I could find that actually worked for my purposes!
(I.e. two forms on one MVC page -> without doing forms inside partials and ajax loads for the partials. This was no good for me, as I wanted to return differing result sets to be rendered outside the form div, depending on which form was submitted)
I would advise a slight modification to the Html Extension though, because you still want a validation summary to be rendered for the non-matched validation summary so that client side validation works:
namespace System.Web.Mvc
{
public static class HtmlExtensions
{
public static MvcHtmlString ActionValidationSummary(this HtmlHelper html, string action)
{
string currentAction = html.ViewContext.RouteData.Values["action"].ToString();
if (currentAction.ToLower() == action.ToLower())
return html.ValidationSummary();
return new MvcHtmlString("<div class=\"validation-summary-valid\" data-valmsg-summary=\"true\"><ul><li style=\"display:none\"></li></ul></div>");
}
}
}
Related
I am working with a custom validation attribute and want to show my validation message, where I will specify a name like this:
return new ValidationResult(FormatErrorMessage("Hobbies"));
I found this html was there on the page:
<span data-valmsg-replace="true" data-valmsg-for="Hobbies" class="field-validation-valid text-danger"></span>
When I return message from the IsValid function of the ValidationAttribute class like this:
return new ValidationResult(FormatErrorMessage("Hobbies"));
Where I specify the name "Hobbies" then it should be added into
<span data-valmsg-for="Hobbies">
Why was my error message was not added?
If you want me to paste full code then please tell me.
I apologize, I'm not completely sure about your question. However, since you said "give me a clue what kind of mistake I have done," I'm going to go with explaining the approach that I've taken in a project which utilizes the ViewModel and a couple of custom validation-handling methods.
I don't think this is a direct answer to your question, but it should give you enough information to be able to make custom methods that build the HTML with the error message content inside it the way you want if you are using MVC w/ razor.
Utilizing ViewModels in razor for validation
Normally, with .NET MVC razor (you didn't mention which version of MVC you were using), you just utilize attributes in the view model for validation, e.g.
public class MyViewModel {
[Required(ErrorMessage = "Required")]
public string Name {get; set;}
}
These automatically get validated on post. This will set the property of the view model "Name" to required, and when the validation fails, the error message will be "Required."
Now, if you are doing some processing server side and doing complex validation that is not easy to setup in attributes, then you can manually add an error to your model, like so (my code for captcha validation):
//inside controller HttpPost method
var isCaptchaValid = ReCaptcha.IsCaptchaValid(Request.Form["g-recaptcha-response"] ?? "");
if (!isCaptchaValid)
{
ModelState.AddModelError("Captcha", "Verification Required");
}
Where "Captcha" is the field name and "Verification Required" is the error message.
Displaying Custom Error Messages
Then, stepping away from the standard approach, I have some classes that will build the Bootstrap 3 class "has-error" for the form-group and a custom error that wraps the error message in a label:
public static class HtmlExtensions {
public static string GetErrorClass(this HtmlHelper htmlHelper, bool hasError)
{
return " has-error";
}
public static MvcHtmlString ErrorLabel<TModel>(this HtmlHelper<TModel> helper, ModelStateDictionary modelState, string fieldName)
{
if (modelState[fieldName] != null )
{
var error = modelState[fieldName].Errors.FirstOrDefault();
if (error != null)
{
var span = new TagBuilder("span");
span.AddCssClass("label label-danger");
span.InnerHtml = error.ErrorMessage;
return MvcHtmlString.Create(span.ToString(TagRenderMode.Normal));
}
}
return MvcHtmlString.Empty;
}
}
From there, you can use it just like any of the other #Html
<div class='form-group#Html.GetErrorClass("Name")'>
<label class='control-label col-xs-12 col-sm-6' for='name'>#Html.ErrorLabel(ViewData.ModelState,"Name") Name:</label>
<div class='col-xs-12 col-sm-6'>
#Html.TextBoxFor(model => model.Name, new { #class = "form-control" })
</div>
</div>
Anyway, I hope that helps you with what you are trying to do. If this is so far away from an answer to your problem, please let me know and I'll remove the answer.
Applying to your HTML requirements:
Oh, and I guess to build the HTML the way you are wanting to, doing it this way, the extension method would look like this:
public static MvcHtmlString MyErrorExtension<TModel>(this HtmlHelper<TModel> helper, ModelStateDictionary modelState, string fieldName)
{
if (modelState[fieldName] != null)
{
var error = modelState[fieldName].Errors.FirstOrDefault();
//<span data-valmsg-replace="true" data-valmsg-for="Hobbies" class="field-validation-valid text-danger"></span>
var span = new TagBuilder("span");
span.Attributes.Add("data-valmsg-replace", "true");
span.Attributes.Add("data-valmsg-for", fieldName);
span.AddCssClass("field-validation-valid text-danger");
if (error != null)
{
span.InnerHtml = error.ErrorMessage;
}
return MvcHtmlString.Create(span.ToString(TagRenderMode.Normal));
}
return MvcHtmlString.Empty;
}
The above method will create your tag regardless, and it will populate it with the first error it finds if there are any errors for that field name.
I am creating a MVC-Project. Using MVC 4 and Razor. After building some pages I was wondering: what is the difference between
MvcHtmlString.Create()
and
Html.Raw()
Would be nice if you could help me here to understand that.
Thanks in advance!
This is an excellent opportunity to look at the source code that's available to us for ASP.NET (https://github.com/aspnet/AspNetWebStack/).
Looking at HtmlHelper.cs, this is the code for Html.Raw():
public IHtmlString Raw(string value)
{
return new HtmlString(value);
}
public IHtmlString Raw(object value)
{
return new HtmlString(value == null ? null : value.ToString());
}
And this is the code for the MvcHtmlString class:
namespace System.Web.Mvc
{
public sealed class MvcHtmlString : HtmlString
{
[SuppressMessage("Microsoft.Security", "CA2104:DoNotDeclareReadOnlyMutableReferenceTypes", Justification = "MvcHtmlString is immutable")]
public static readonly MvcHtmlString Empty = Create(String.Empty);
private readonly string _value;
public MvcHtmlString(string value)
: base(value ?? String.Empty)
{
_value = value ?? String.Empty;
}
public static MvcHtmlString Create(string value)
{
return new MvcHtmlString(value);
}
public static bool IsNullOrEmpty(MvcHtmlString value)
{
return (value == null || value._value.Length == 0);
}
}
}
The most significant difference is that Html.Raw() accepts any object, while MvcHtmlString.Create() only accepts strings.
Also, Html.Raw() returns an interface, while the Create method returns an MvcHtmlString object.
Lastly, the Create deals with null differently.
There is no practical difference.
The MvcHtmlString.Create creates an instance of MvcHtmlString, while the Html.Raw method creates an instance of HtmlString, but MvcHtmlString just inherits from HtmlString, so they work the same.
The other answers focus more on the technical differences, if there are any. I think however there is another aspect: They serve different use cases / are used in different situations.
Html.Raw(...) is a method of IHtmlHelper. These are intented for use in razor views. It can be used to render raw HTML strings 'as is', without them getting encoded.
Since rendering user generated HTML content can be a security risk, it is very important to know when a string can contain HTML code, and for it to be sanitized. One of the main sources of security problems with old languages like ASP and PHP is rendering strings un-encoded per default, so you can see why, per default, ASP.NET MVC renders strings encoded. You want the (few) cases where your program renders a raw HTML string to be 'opt-in' and clear to see.
To better indicate these cases, it is good practice to store the HTML strings in a dedicated data type, like HtmlString. These objects will be rendered un-encoded, so you don't need Html.Raw. For this you can use MvcHtmlString.Create(...), or, more simply, new HtmlString(...), even if you don't have access to an IHtmlHelper (for example in a view model).
To illustrate this, consider this example of a view model for an ASP.NET MVC view with a title that does not contain HTML, and a content that does:
class MyViewModel
{
public string Title { get; set; }
public HtmlString SomeHtmlContent { get; set; }
}
This can be rendered on the page like this - notice that you don't need Html.Raw to render the HTML content:
<div>
<h1>#Model.Title</h1>
<div>
#Model.SomeHtmlContent
</div>
<div>
Previous to MVC, when webforms was the only thing we had, I used to define a container for my controls (A Box you may call) and used this web control (with title, body and a couple of other properties) in other controls.
So if I wanted to change the look of all my visual controls, I just had to make one change in my Box control.
Here's a simplified snippet of what I used to do:
<%# Control Language="C#" AutoEventWireup="true" CodeBehind="Box.ascx.cs" Inherits="WebApp.Controls.Box" %>
<span class="boxtitle">
<asp:Literal ID="ltrTitle" runat="server"></asp:Literal>
</span>
<div class="boxContent" id="dvBox">
<asp:PlaceHolder runat="server" ID="BoxBodyContainer"/>
</div>
And in code-behind:
public Control BoxBody { get; set; }
public string Title
{
get { return this.ltrTitle.Text; }
set { this.ltrTitle.Text = value; }
}
protected void Page_Load(object sender, EventArgs e)
{
this.BoxBodyContainer.Controls.Add(this.BoxBody);
}
So I could use this along with other controls in my page as follows:
<MyControls:Box ID="Box1" Title="Foo" runat="server">
<boxbody>
<MyControls:CustomControl ID="Bar" runat="server" >
</MyControls:CustomControl>
</boxbody>
</MyControls:Box>
In order to have something alike in MVC 3, I think I should define a Box view and wherever I need the box, use Html.Partial or Html.Action and pass all my data (title, boxbody, etc) to this view and use #Html.Raw in Box view.
But I was wondering if there's any better, more standard way to achieve this.
What's the correct way of achieving this in MVC 3 (Razor)?
You can create an Html Helper extension method to do this. The best tutorial I could find was for MVC2, but it gives you the basics.
What the tutorial doesn't cover is that there are classes in the System.Web.MVC namespace that can help you create html in code.
Note: The following code hasn't been tested.
using System;
using System.Web.Mvc;
public static class HtmlExtensions
{
public static MvcHtmlString Box(this HtmlHelper helper, string title, MvcHtmlString body)
{
TagBuilder span = new TagBuilder("span");
span.AddCssClass("boxtitle");
span.SetInnerText(title.ToString());
TagBuilder div = new TabBuilder("div");
div.AddCssClass("boxContent");
div.InnerHtml = body;
return MvcHtmlString.Create(span.ToString() + div.ToString());
}
}
You can call this method from the razor view like so:
#Html.Box("foo", Html.Partial("bar"))
I wish to display content depending on the given role(s) of the active user , in the ASP.NET MVC.
Compare the old fashion way, using WebForms:
protected void Page_Load(Object sender, EventArgs e)
{
if(User.IsInRole("Administrator")) {
adminLink.Visible = true;
}
}
Now how would I go on writing that when using the ASP.NET MVC ?
From my point of view, it would be wrong to place it directly in the View File, and assigning a variable for every single view won't be pretty either.
Create Html helper and check current user roles in its code:
public static class Html
{
public static string Admin(this HtmlHelper html)
{
var user = html.ViewContext.HttpContext.User;
if (!user.IsInRole("Administrator")) {
// display nothing
return String.Empty;
// or maybe another link ?
}
var a = new TagBuilder("a");
a["href"] = "#";
a.SetInnerText("Admin");
var div = new TagBuilder("div") {
InnerHtml = a.ToString(TagRenderMode.Normal);
}
return div.ToString(TagRenderMode.Normal);
}
}
UPDATED:
Or create wrapper for stock Html helper. Example for ActionLink(this HtmlHelper htmlHelper, string linkText, string actionName, string controllerName):
public static class Html
{
public static string RoleActionLink(this HtmlHelper html, string role, string linkText, string actionName, string controllerName)
{
return html.ViewContext.HttpContext.User.IsInRole(role)
? html.ActionLink(linkText, actionName, controllerName)
: String.Empty;
}
}
No you would be placing it in the view file, like so actually:
<% If (User.IsInRole("Administrator")) { %>
<div>Admin text</div>
<% } %>
this worked for me:
<% MembershipUser mu = Membership.GetUser();
if (mu != null)
if (Roles.IsUserInRole(mu.UserName, "Administrator"))
{
%>
<li class="paddingleftThree"><%= Html.ActionLink("User Administration", "GetUsers", "Account")%></li> <%} %>
The separation of concerns approach suggested in ASP.NET MVC 4 How do you serve different HTML based on Role? in my opinion is a better way to go.
Personally I avoid IsInRole check as much as possible in the code and leave it to declarative means to achieve role based restriction as much as possible. This ensures code remains maintainable over time. I am not sure if this is a right or the wrong approach, but has worked well for me.
There has been many discussion on ASP.NET MVC and Codebehind-files, mostly where it has been pointed out that these Codebehind-files are evil.
So my question is, how do you handle page-specific logic?
What we don't want here is spaghetti-code in the inline-code and we don't want page-specific code scattered throughout helper-classes or on top of the HTML-helper-class.
An example would be:
<% for(int i = 0; i < companyList.Count; i++) { %>
RenderCompanyNameWithRightCapsIfNotEmpty(company, i)
<% } %>
With accompanying codebehind:
private string RenderCompanyNameWithRightCapsIfNotEmpty(string company, index)
{
if (index == 0) {
return string.Format("<div class=\"first\">{0}</div>", company);
}
// Add more conditional code here
// - page specific HTML, like render a certain icon
string divClass = (index % 2 == 0) ? "normal" : "alternate";
return string.Format("<div class=\"{1}\">{0}</div>", company, divClass);
}
This will only be used on one page and is most likely subject to change.
Update: A couple approaches I thought about where these:
1) Inline codebehind on page - with simple methods that returns strings.
<script runat="server">
private string RenderCompanyHtml(string companyName) ...
<script>
2) Putting a method which returns a string in the Controller. But that would be putting View-logic into the Controller.
public class SomeController : Controller
{
[NonAction]
private static string RenderCompanyHtml(string companyName) ...
public ActionResult Index() ...
}
You should put that code in the controlleraction where you prepare the viewdata.
I usually make a region "helper methods" in my controller class with a few [NonAction] methods to keep things clean.
So my (simplified) controller would look like this:
public class SomeController : Controller
{
#region Helper methods
[NonAction]
private static string CompanyNameWithRightCapsIfNotEmpty(string company)
{
if (string.IsNullOrEmpty(company)) {
return company;
}
return UpperCaseSpecificWords(company);
}
#endregion
public ActionResult Companies()
{
var companies = GetCompanies();
var companyNames = companies.Select(c => CompanyNameWithRightCapsIfNotEmpty(c.Name));
ViewData["companyNames"] = companyNames;
return view();
}
}
Helper methods are one good way of handling page specific code, but I think it is a;ways preferable to get your model to show the data you need.
If you're going to go for the helper option, you would be better served by making the operation it perfroms a bit less page specific. If your method RenderCompanyNameWithRightCapsIfNotEmpty has to be so specific it would be better if your model provided it. One way would be to have the model provide a list with the text already formatted, and expose it as a public property (say an IEnumerable of formatted company names).
Use Html Helpers.
Like so create the helper methods in a static class:
public static string Label(this HtmlHelper helper, string target, string text)
{
return String.Format("<label for='{0}'>{1}</label>", target, text);
}
.. then use in your view:
<span><% =Html.Label("FinishDateTime.LocalDatetime", "Finish Time:")%><br />
You could create a helper method called maybe RenderCompanyName(string[] companies) that checked for nulls, did the caps manipulation and rendered the html in between - all in the same helper if you like.
Also: controller action methods should be light - ie. only getting the data and returning views. You should delegate things like manipulation of data for presentation to views and Html helpers.
EDIT: Here is a helper that you might be after:
This helper renders an IList<> to html in the form of an unordered list <ul>...</ul>. The useful thing about it is that it gives you control over how the list is rendered thru css AND it allows you to render additional html/content for each item. Take a look - this is the helper:
public static string UnorderedList<TItem>(this HtmlHelper helper,
IList<TItem> items, Func<TItem, string> renderItemHtml,
string ulID, string ulClass, string liClass)
{
StringBuilder sb = new StringBuilder();
// header
if (!ulID.IsNullOrTrimEmpty()) sb.AppendFormat("<ul id='{0}'", helper.Encode(ulID.Trim()));
else sb.AppendFormat("<ul");
if (!ulClass.IsNullOrTrimEmpty()) sb.AppendFormat(" class='{0}'>", helper.Encode(ulClass.Trim()));
else sb.AppendFormat(">");
// items
foreach (TItem i in items)
{
if (!liClass.IsNullOrTrimEmpty())
sb.AppendFormat("<li class='{0}'>{1}</li>", helper.Encode(liClass.Trim()),
renderItemHtml(i));
else
sb.AppendFormat("<li>{0}</li>", renderItemHtml(i));
}
// footer
sb.AppendFormat("</ul>");
return sb.ToString();
}
..using it is easy. here is a simple example to render a list of tags:
<div id="tags">
<h2>Tags</h2>
<%=Html.UnorderedList<Tag>(Model.Tags.Tags,tag=>
{
return tag.Name;
},null,null,null) %>
</div>
..you can see in my usage example that i have chosen not to specify any css or id attribute and i simply return the name of the Tag item thru the use of the anonymous delegate. Anonymous delegates are way easy to use.. in your case maybe something like this would work:
<div id="tags">
<h2>Tags</h2>
<%=Html.UnorderedList<string>(ViewData["companies"],company=>
{
if (someCondition) return company.ToUpper();
else return company;
},null,null,null) %>
</div>
.. ViewData["companies"] is an IList<string> for simplicity.