I'm rendering a usual textarea like this:
#Html.TextAreaFor(x => x.Description)
I expected to see an empty textarea but here is what I see instead (I selected the first line to make it more clear):
I checked out the generated html and it contains a line break between an opening and closing tags:
<textarea class="form-control" cols="20" id="Description" name="Description" rows="2">
</textarea>
Is that done by design? Can I change this behaviour?
After saw your question, I research on Google to see what is the issue behind extra line in #Html.TextAreaFor. Have a look.
There are some articles those are related to your issue:-
http://www.peschuster.de/2011/11/new-line-bug-in-asp-net-mvcs-textarea-helper/
ASP.NET MVC Textarea HTML helper adding lines when using AntiXssLibrary
Articles suggested that basic issue in TextAreaHelper class which is used by #Html.TextAreaFor.
private static MvcHtmlString TextAreaHelper(HtmlHelper htmlHelper,
ModelMetadata modelMetadata, string name, IDictionary<string,
object> rowsAndColumns, IDictionary<string, object> htmlAttributes)
{
// Some initialization here...
TagBuilder tagBuilder = new TagBuilder("textarea");
// Some more logic...
tagBuilder.SetInnerText(Environment.NewLine + attemptedValue);
return tagBuilder.ToMvcHtmlString(TagRenderMode.Normal);
}
and the issue in above code is
tagBuilder.SetInnerText(Environment.NewLine + attemptedValue);
That's why actual output of #Html.TextAreaFor will be like this and extra line shows up:-
<textarea>
This is the content...</textarea>
The workaround of this problem is to
1st Workaround Implementing a Javascript onLoad fix to remove the offending encoding from all textareas:
$("textarea").each(function () { $(this).val($(this).val().trim()); });
2nd Workaround create your own helper for rendering textarea markup in views
public static MvcHtmlString FixedTextAreaFor<TModel, TProperty>(
this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression)
{
return new MvcHtmlString(htmlHelper.TextAreaFor(expression)
.ToHtmlString()
.Replace(">
", ">" + Environment.NewLine));
}
These articles also suggested that this problem will be fixed in MVC 4 Developer Preview!
Related
I'm creating a website with ASP.NET MVC5 and I'm using MaterializeCSS for the first time, which looks like a very exciting framework.
However, the checkboxes generated by CheckBoxFor helper become hidden !
When I write :
#Html.CheckBoxFor(m => m.IsAgreeTerms)
The generated HTML is :
<input name="IsAgreeTerms" type="hidden" value="false">
Why does Materialize change my type=checkbox into type=hidden ?
I tried to add type="checkbox" in the CheckboxFor helper, but it doesnt change anything. The only way is to modify in in my browser's console.
The only solution I found is this SO thread.
However, the accepted answer doesn't change anything for me.
The other answer works, but I think it's ugly to add some JS script to modify what Materialize modifies without my consent.
Is there any way to say "Hey, I ask for a type=checkbox, so just let my type=checkbox in the generated HTML" ?
Thank you
UPDATE :
My full ASP.NET MVC code is :
#Html.CheckBoxFor(m => m.IsAgreeTerms, new { #type = "checkbox" })
#Html.LabelFor(m => m.IsAgreeTerms, new { #class = "login-label" })
The full generated HTML is
<input data-val="true" data-val-required="Le champ IsAgreeTerms est requis." id="IsAgreeTerms" name="IsAgreeTerms" type="checkbox" value="true"
<input name="IsAgreeTerms" type="hidden" value="false">
<label class="login-label" for="IsAgreeTerms">IsAgreeTerms</label>
Here's a solution in the form of a html helper. It constructs a checkbox and label in the correct order:
public static IHtmlString CheckBoxWithLabelFor<TModel>(
this HtmlHelper<TModel> htmlHelper,
Expression<Func<TModel, bool>> expression,
string labelText,
object htmlAttributes = null
)
{
if (expression == null)
{
throw new ArgumentNullException(nameof(expression));
}
var checkBoxWithHidden = htmlHelper.CheckBoxFor(expression, htmlAttributes).ToHtmlString().Trim();
var pureCheckBox = checkBoxWithHidden.Substring(0, checkBoxWithHidden.IndexOf("<input", 1, StringComparison.Ordinal));
var labelHtml = htmlHelper.LabelFor(expression, labelText).ToHtmlString().Trim();
var result = pureCheckBox + Environment.NewLine + labelHtml + Environment.NewLine + $"<input type=\"hidden\" name=\"{ExpressionHelper.GetExpressionText(expression)}\" value=\"false\" />";
return new MvcHtmlString(result);
}
Is there other html generated by materialize.css? I think this happens because it is not possible apply a custom CSS to element input of type checkbox.
So, the checkbox becomes hidden and other html component represents visually the checkbox. Many components work like that.
UPDATE:
Why is Html checkbox generating an additional hidden input
OP here. Problem looks like more complex.
Actually, when using #Html.CheckBoxFor, MVC5 generates 3 fields, in that order :
Your input, with type="checkbox", binded to your model property
An hidden field (see the Claudio's link for an explaination)
Your label, generated by #Html.LabelFor
Problem is Materialize expects that in another order to work.
In your browser's console, just move the <label> element between the input and the hidden field, and everything works fine !
I found this very useful link, where, basically, it is said that the order of the generated fields by #Html.checkBoxFor will change ... In MVC6 !
As I'm working with MVC5, I use this very ugly solution in my _Layout:
$(":checkbox").each(function () {
$(this).nextAll("label").before($(this))
})
If anyone has a better idea, please feel free to post an elegant solution.
I don't know how to output a variable in Razor as part of an attribute name after a dash:
<span data-#(DataAttributeName)="value"/>
// fails, output:
<span data-#(DataAttributeName)="value"/>
<span data- #(DataAttributeName)="value"/>
// works, however, the space results in invalid HTML:
<span data- myname="value"/>
How to do that properly?
Currently, I have the following workaround:
<span #("data-" + DataAttributeName)="value"/>
But I don't like it for obvious style reasons + Visual Studio tells me that "an attribute name is expected" and shows an error (although it seems to work properly), also something I don't like.
That's a tricky part in razor engine, it tries to be smart to save some escape but sometimes leave no easy solution in scenarios like this.
Just to stay neat, I may create a HtmlHelper Extension, which might be a overkill, but just in case you are sick of red things in editor like me :)
public static class MyHtmlHelperExtension
{
public static MvcHtmlString DataAttribute(this HtmlHelper helper, string attrName, string value)
{
return new MvcHtmlString(string.Format("data-{0}='{1}'", attrName, value));
}
}
Then in your view it can be somehow cleaner:
<span #Html.DataAttribute(DataAttributeName, "value") />
I have a model that contains a collection, such as this:
class MyModel
{
public List<MySubModel> SubModels { get; set; }
}
In the view, I want to dynamically add/remove from this list using Javascript before submitting. Right now I have this:
$("#new-submodel").click(function () {
var i = $("#submodels").children().size();
var html = '<div>\
<label for="SubModels[' + i + '].SomeProperty">SomeProperty</label>\
<input name="SubModels[' + i + '].SomeProperty" type="textbox" />\
</div>'
$("#submodels").append(html);
});
This works, but it's ugly. And, if I want to show those labels/textboxes for the existing items, there's no clean way to do that either (without duplicating).
I feel like I should be able to use Razor helpers or something to do this. Any ideas? Help me stay DRY.
You approach may lead to unexpected errors if you when you are removing or adding the divs. For example you have 4 items, you remove the first item, then $('#submodels').children().size() will return 3, but your last inserted div has the name attribute value set SubModels[3].SomeProperty which results in a conflict. And if your posted values contain SubModels[1] but not SubModels[0] the default model binder will fail to bind the list (it will bind it as null). I had to learn this the hard way...
To eliminate the aforementioned problem (and your's) I suggest you do something like this:
$("#addBtn").click(function() {
var html = '<div class="submodel">\
<label>SomeProperty</label>\
<input type="textbox" />\
</div>'; // you can convert this to a html helper!
$("#submodels").append(html);
refreshNames(); // trigger after html is inserted
});
$(refreshNames); // trigger on document ready, so the submodels generated by the server get inserted!
function refreshNames() {
$("#submodels").find(".submodel").each(function(i) {
$(this).find("label").attr('for', 'SubModels[' + i + '].SomeProperty');
$(this).find("label").attr('input', 'SubModels[' + i + '].SomeProperty');
});
}
Then your view (or even better an EditorTemplate for the SubModel type) can also generate code like:
<div class="submodel">
#Html.LabelFor(x => x.SomeProperty);
#Html.EditorFor(x => x.SomeProperty);
</div>
It would also be possible to convert the code generation to a html helper class, and use it in the EditorTemplate and in the JavaScript code
I would recommend you going through the following blog post.
Is there a utility function for escaping JavaScript in ASP.NET MVC views? I often need to init a little snippet of JavaScript using some values from the view; for instance I may have something like:
<script type="text/javascript">
var page = new Page({ currentUser: "<%= Model.UserName %>" });
page.init();
</script>
I would expect something like:
<script type="text/javascript">
var page = new Page({ currentUser: "<%= Html.JavaScriptEscape(Model.UserName) %>" });
page.init();
</script>
I could, of course, write the function myself. But since there are already built-in utilities form HTML encoding, and since one of the selling points of ASP.NET MVC is that the <% %> is the default rendering mode, and since what I'm trying to achieve is quite common, it makes me wonder why I cannot find anything like that already built-in. Is there, for instance, an easy and elegant way to serialize an object to JSON in views?
Or am doing something against ASP.NET MVC principles? When I hit a problem like this, it usually makes it think that either I’m doing something wrong since I assume that the framework designers spent some time thinking about real world scenarios.
In .NET 4, The HttpUtility class has a variety of static encoding methods for various contexts, including a JavaScriptStringEncode method for this particular purpose.
It's often simpler to just use JSON deserialization, though.
In MVC 5 using Razor templates, the following is possible:
<script type="text/javascript">
var page = new Page({ currentUser: #Html.Raw(Json.Encode(Model.UserName)) });
page.init();
</script>
After some time working in ASP.NET MVC, I concluded that (most likely) there is no build-in helper for it. Of course, it's trivial to write your own. Here is it for the sake of completeness:
using System.Web.Mvc;
using System.Web.Script.Serialization;
namespace MyProject.Helpers
{
public static class JsonExtensions
{
public static string Json(this HtmlHelper html, object obj)
{
JavaScriptSerializer jsonSerializer = new JavaScriptSerializer();
return jsonSerializer.Serialize(obj);
}
}
}
In a view, it can be used as follows:
<script type="text/javascript">
var page = new Page(<%= Html.Json(new { currentUser: Model.UserName } ) %>);
page.init();
</script>
In my case I needed a string not a json object and this is for Asp.Net Core:
#functions{
public Microsoft.AspNetCore.Html.IHtmlContent ToJS(string value)
{
return Html.Raw("'" + value.Replace("'", "\\'").Replace("\r", "\\r").Replace("\n", "\\n") + "'");
}
public Microsoft.AspNetCore.Html.IHtmlContent ToJS(int value)
{
return Html.Raw("" + value);
}
}
This will escape the ' and end of line characters. Also it leaves numbers (int) as a number. This could be overloaded to include float, decimal, etc. as needed.
So, I don't have to think about it or do anything different for each type:
var serverName = #ToJS(m.ServerName);
var appSiteUrl = #ToJS(m.SiteUrl);
var facebookId = #ToJS(m.FacebookAppId);
I have this cute little progress bar looking thing in a dashboard page. Once it is started up, it updates itself every minute via ajax, javascript, blah, blah. Since some of my viewers are looking at it on older Blackberries, I normally figure out how big the bar should be for the initial rendering server-side, and draw the page accordingly, then let the javascript take over after that, on those viewers that have it.
The old code, plain old ASP.NET has an asp:Label in the page where the img tag goes, and on the server I cat together the whole thing. As I refactor to an MVC way of looking at things, I thought how wonderful it would be to only write the width style attribute of the image on the server. The code on the page would be a good deal more understandable that way.
But it doesn't work. Example:
<img src="/content/images/blue_1px.png" class="productionBar_variableBar"
style="width: <% =dbd["ThisShiftProduction_variableBar"] %>;"/>
Unfortunately, Visual Studio doesn't seem to recognize the <% %> escape inside of the quoted style attribute.
Any suggestions?
Siggy
The simplest way - creating HtmlHelper extension:
public static class Html
{
public static string ProgressBar(this HtmlHelper html, int width)
{
StringBuilder sb = new StringBuilder();
sb.AppendFormat("img src=\"/content/images/blue_1px.png\" class=\"productionBar_variableBar\" style=\"width: {0};\" />", width);
return sb.ToString();
}
// OR
public static string ProgressBar(this HtmlHelper html, int width, string src, string cssClass)
{
TagBuilder tagBuilder = new TagBuilder("img");
tagBuilder.AddCssClass(cssClass);
tagBuilder.MergeAttribute("style", "width: " + width.ToString());
string srcUrl = new UrlHelper(html.ViewContext.RequestContext).Content(src);
tagBuilder.MergeAttribute("src", srcUrl);
return tagBuilder.ToString(TagRenderMode.Normal);
}
}
Using it:
<%= Html.ProgressBar(dbd["ThisShiftProduction_variableBar"]) %>
<!-- OR -->
<%= Html.ProgressBar(dbd["ThisShiftProduction_variableBar"], "~/content/images/blue_1px.png", "productionBar_variableBar") %>
Have you tried doing this instead
<img src="/content/images/blue_1px.png" class="productionBar_variableBar" style='width: <% =dbd["ThisShiftProduction_variableBar"] %>;'/>
Notice the single quotes instead of the double quotes in the style attribute