is it possible to use dash (-) in a member name of an anonymous class? I'm mainly interested in this to use with asp.net mvc to pass custom attributes to html-helpers, since I want my html to pass html5-validation, this starting with data-.
Exemple that doesn't work:
<%=Html.TextBoxFor(x => x.Something, new {data-animal = "pony"})%>
Putting a # in front of the member name doesn't do the trick either.
Update: If this isn't possible, is there a recommended way todo what I want? My current temporary solution is to add a replace to the whole thing like this:
<%=Html.TextBoxFor(x => x.Something, new {data___animal = "pony"}).Replace("___", "-")%>
But that sucks, because it's ugly and will break when Model.Something contains three underscores. Buhu.
Just found this post while searchching for the same problem.
I found this link:
http://blogs.planetcloud.co.uk/mygreatdiscovery/post/Using-custom-data-attributes-in-ASPNET-MVC.aspx
It resolves the problem. It mentions the following:
[...] or better yet, just use code from ASP.NET MVC source:
public static RouteValueDictionary AnonymousObjectToHtmlAttributes(object htmlAttributes)
{
RouteValueDictionary result = new RouteValueDictionary();
if (htmlAttributes != null)
{
foreach (System.ComponentModel.PropertyDescriptor property in System.ComponentModel.TypeDescriptor.GetProperties(htmlAttributes))
{
result.Add(property.Name.Replace('_', '-'), property.GetValue(htmlAttributes));
}
}
return result;
}
Collecting the Asp-Mvc version specific ways to do data- here:
MVC 3+ : Use an underscore _ and it will be automatically replaced by mvc
MVC 1?,2: see #Jean-Francois answer, which points to this
No, because the dash is a C# operator (minus), and white space isn't significant.
Right now the compiler thinks you are trying to subtract animal from data, which doesn't work unless the - operator is specified for the types in question.
It is not possible to use - as part of any identifier.
http://msdn.microsoft.com/en-us/library/aa664670(VS.71).aspx
No, you can't use the hyphen character. You need to use alphanumeric characters, underscores, or the other characters described here. '-' is treated as a minus. data-animal would be treated the same as data - animal, so that won't even compile unless you have separately defined data and animal (and it could present subtle bugs if you have!).
Edit: With C#'s capability to have identifiers with Unicode escape sequences, you can get the effect of a dash in an identifier name. The escape sequence for "&mdash" (the longer dash character) is "U+2014". So you would express data-animal as data\u2014animal. But from a coding style point of view, I'm not sure why you wouldn't choose a more convenient naming convention.
Also, another point to highlight from "2.4.2 Identifiers (C#)": You can't have two of these escape sequences back to back in an identifier (e.g. data\u2014\u2014animal).
Related
Let's say I want to assign a text (which contains many double quotes) into variable. However, the only way seems to manually escape:
string t = "Lorem \"Ipsum\" dummy......
//or//
string t = #"Lorem ""Ipsum"" dummy.....
Is there any way to avoid manual escaping, and instead use something universal (which I dont know in C#) keywoard/method to do that automatically? In PHP, it's untoldly simple, by just using single quote:
$t = 'Lorem "Ipsum" dummy .......
btw, please don't bomb me with critiques "Why do you need to use that" or etc. I need answer to the question what I ask.
I know this answer may not be satisfying, but C# sytnax simply won't allow you to do such thing (at the time of writing this answer).
I think the best solution is to use resources. Adding/removing and using strings from resources is super easy:
internal class Program
{
private static void Main(string[] args)
{
string myStringVariable = Strings.MyString;
Console.WriteLine(myStringVariable);
}
}
The Strings is the name of the resources file without the extension (resx):
MyString is the name of your string in the resources file:
I may be wrong, but I conjecture this is the simplest solution.
No. In C# syntax, the only way to define string literals is the use of the double quote " with optional modifiers # and/or $ in front. The single quote is the character literal delimiter, and cannot be used in the way PHP would allow - in any version, including the current 8.0.
Note that the PHP approach suffers from the need to escape ' as well, which is, especially in the English language, frequently used as the apostrophe.
To back that up, the EBNF of the string literal in current C# is still this:
regular_string_literal '"' { regular_string_literal_character } '"'
The only change in the compiler in version 8.0 was that now, the order of the prefix modifiers $ (interpolated) and # (verbatim) can be either #$ or $#; it used to matter annoyingly in earlier versions.
Alternatives:
Save it to a file and use File.ReadAllText for the assignment, or embed it as a managed ressource, then the compiler will provide a variable in the namespace of your choice with the verbatim text as its runtime value.
Or use single quotes (or any other special character of your choice), and go
var t = #"Text with 'many quotes' inside".Replace("'", #"""");
where the Replace part could be modeled as an extension to the String class for brevity.
I have to encode strings to remove parentheses for Ids for HTML elements.
Parentheses (these ones (,)) aren't valid in HTML Ids, are there standard strings (like those used in URLs) to use?
Is there an existing method that can be used in ASP.NET MVC?
N.B. System.Web.Mvc.HttpUtility.HtmlEncode(string), does not encode parentheses.
As per the HTML specification (and this question about id's) parentheses aren't allowed in the HTML id attribute. If you need them, you could use string replace, e.g.:
// ( = 'op--' Opening Parenthesis
// ) = 'cp--' Closing Parenthesis
string id = "collectionName.get_Item(index)";
// encode
string encodedId = id.Replace("(", "op--").Replace(")", "cp--");
// decode
string decodedId = encodedId.Replace("op--", "(").Replace("cp--", ")");
I don't think I understand the question, cos it feels like the answer is to substitute [ and ]. Or even %28 and %29 from the Wikipedia link you gave.
Have I got hold of the wrong end of the stick?
EDIT: From what has been said in the comments, it seems that %28 and %29 are not okay as the % character is also invalid, in which case you could select a substitute that won't appear elsewhere.
EG Something like ( becomes ---28--- (or even ---openbracket---) or something else you can guarantee won't appear elsewhere in the ID (which should be possible).
If the elements are dynamically created then why not just do a .Replace on the id changing parentheses for, say, underscores?
If the elements are not dynamically created then why do they have parentheses in the ids?!
I have a database field (postcode) that I want to contain upper case characters, spaces and numbers. No lower case or other punctuation. I'd like to deal with that as declaratively as possible. One way would be to use a regular expression DataAnnotation to validate, [A-Z][0-9]\w (or similar - I'm not a regular expression expert, but I'm sure the right regular expression is there to be found). That would do half of what I want - it would force the user to input in uppercase, but it wouldn't convert to uppercase.
If I want to convert to uppercase there are some solutions in Stack Overflow question How can I force input to uppercase in an ASP.NET textbox?, but none of them are particularly declarative. At the moment I'm thinking of a combination of the validation and jQuery to spot anything with a class of "uppercaseonly" and convert the data, but it's a bit messy.
Am I missing anything?
CSS text-transform: uppercase?
http://www.w3schools.com/css/pr_text_text-transform.asp
UPDATE:
Try implementing a custom ModelBinder. Here's an example: http://www.agileatwork.com/custom-model-binder-in-asp-net-mvc/
Instead of AddRoles just set the property to uppercase. No need to touch your EF classes.
Why not just change the setter to store the received value as uppercase?
So, in your class object, instead of the shorthand property { get; set; } change to;
get { return this.property; }
set { this.property = value.ToUpper(); }
In my answer to this question, I mentioned that we used UpperCamelCase parsing to get a description of an enum constant not decorated with a Description attribute, but it was naive, and it didn't work in all cases. I revisited it, and this is what I came up with:
var result = Regex.Replace(camelCasedString,
#"(?<a>(?<!^)[A-Z][a-z])", #" ${a}");
result = Regex.Replace(result,
#"(?<a>[a-z])(?<b>[A-Z0-9])", #"${a} ${b}");
The first Replace looks for an uppercase letter, followed by a lowercase letter, EXCEPT where the uppercase letter is the start of the string (to avoid having to go back and trim), and adds a preceding space. It handles your basic UpperCamelCase identifiers, and leading all-upper acronyms like FDICInsured.
The second Replace looks for a lowercase letter followed by an uppercase letter or a number, and inserts a space between the two. This is to handle special but common cases of middle or trailing acronyms, or numbers in an identifier (except leading numbers, which are usually prohibited in C-style languages anyway).
Running some basic unit tests, the combination of these two correctly separated all of the following identifiers: NoDescription, HasLotsOfWords, AAANoDescription, ThisHasTheAcronymABCInTheMiddle, MyTrailingAcronymID, TheNumber3, IDo3Things, IAmAValueWithSingleLetterWords, and Basic (which didn't have any spaces added).
So, I'm posting this first to share it with others who may find it useful, and second to ask two questions:
Anyone see a case that would follow common CamelCase-ish conventions, that WOULDN'T be correctly separated into a friendly string this way? I know it won't separate adjacent acronyms (FDICFCUAInsured), recapitalize "properly" camelCased acronyms like FdicInsured, or capitalize the first letter of a lowerCamelCased identifier (but that one's easy to add - result = Regex.Replace(result, "^[a-z]", m=>m.ToString().ToUpper());). Anything else?
Can anyone see a way to make this one statement, or more elegant? I was looking to combine the Replace calls, but as they do two different things to their matches it can't be done with these two strings. They could be combined into a method chain with a RegexReplace extension method on String, but can anyone think of better?
So while I agree with Hans Passant here, I have to say that I had to try my hand at making it one regex as an armchair regex user.
(?<a>(?<!^)((?:[A-Z][a-z])|(?:(?<!^[A-Z]+)[A-Z0-9]+(?:(?=[A-Z][a-z])|$))|(?:[0-9]+)))
Is what I came up with. It seems to pass all the tests you put forward in the question.
So
var result = Regex.Replace(camelCasedString, #"(?<a>(?<!^)((?:[A-Z][a-z])|(?:(?<!^[A-Z]+)[A-Z0-9]+(?:(?=[A-Z][a-z])|$))|(?:[0-9]+)))", #" ${a}");
Does it in one pass.
not that this directly answers the question, but why not test by taking the standard C# API and converting each class into a friendly name? It'd take some manual verification, but it'd give you a good list of standard names to test.
Let's say every case you come across works with this (you're asking us for examples that won't and then giving us some, so you don't even have a question left).
This still binds UI to programmatic identifiers in a way that will make both programming and UI changes brittle.
It still assumes your program will only be used in one language. Either your potential market it so small that just indexing an array of names would be scalable enough (e.g. a one-client bespoke or in-house project), or you are assuming you will never be successful enough to need to be available to other languages or other dialects of your first-chosen language.
Does "well, it'll work as long as we're a failure" sound like a passing grade in balancing designs?
Either code it to use resources, or else code it to pass the enum name blindly or use an array of names, as that at least will be modifiable afterwards.
PHP has a great function called htmlspecialcharacters() where you pass it a string and it replaces all of HTML's special characters with their safe equivalents, it's almost a one stop shop for sanitizing input. Very nice right?
Well is there an equivalent in any of the .NET libraries?
If not, can anyone link to any code samples or libraries that do this well?
Try this.
var encodedHtml = HttpContext.Current.Server.HtmlEncode(...);
System.Web.HttpUtility.HtmlEncode(string)
Don't know if there's an exact replacement, but there is a method HtmlUtility.HtmlEncode that replaces special characters with their HTML equivalents. A close cousin is HtmlUtility.UrlEncode for rendering URL's. You could also use validator controls like RegularExpressionValidator, RangeValidator, and System.Text.RegularExpression.Regex to make sure you're getting what you want.
Actually, you might want to try this method:
HttpUtility.HtmlAttributeEncode()
Why? Citing the HtmlAttributeEncode page at MSDN docs:
The HtmlAttributeEncode method converts only quotation marks ("), ampersands (&), and left angle brackets (<) to equivalent character entities. It is considerably faster than the HtmlEncode method.
In an addition to the given answers:
When using Razor view engine (which is the default view engine in ASP.NET), using the '#' character to display values will automatically encode the displayed value. This means that you don't have to use encoding.
On the other hand, when you don't want the text being encoded, you have to specify that explicitly (by using #Html.Raw). Which is, in my opinion, a good thing from a security point of view.