Unexpected "string" keyword after "@" character. Once inside code, you do not need to prefix constructs like "string" with "@"

After upgrading an ASP.NET MVC 3 project to MVC 4 I noticed a change in the Razor parser that threw a Parser Error saying: 'Unexpected "string" keyword after "@" character. Once inside code, you do not need to prefix constructs like "string" with "@"'

Firstly this has always working when it was MVC 3 and Razor v1. I may have been getting the syntax wrong all along but if the syntax allowed it was it really wrong?

What I was doing was trying to put some server code in a Razor helper with no surrounding HTML tags, like this example:

@helper Currency1000s(int? value)
{
    if(value == null)
    {
        -
    }
    else
    {
        @string.Format("{0:C0}k", value / 1000.0)
    }
}

Interestingly if I were to replace line 9 with @value all would be fine. Anyway, it is an easy enough fix, you just need to wrap the string.Format in HTML tags or the text tags as I did here:

@helper Currency1000s(int? value)
{
    if(value == null)
    {
        -
    }
    else
    {
        @string.Format("{0:C0}k", value / 1000.0)
    }
}

Build Visual Studio solutions without Visual Studio

I have a project that has four separate Visual Studio solutions. It is a bit annoying when I do an update from SVN and have to open each solution in Visual Studio just so I can build them. Visual Studio is hardly a lightweight program so surely there's a simpler way?

Most sys admins or developers accustomed to automated builds will probably start to titter at this point, but you can do it easily using NotePad (and the various stuff already installed on your dev machine). I don't want a mega complex system to deploy in a special way to a different server using expensive software, I just want to build everything without having to load many Visual Studio instances. So here is how.

Simple way to build all solutions with a batch file

First open NotePad and write the following code:

@echo off
CALL "C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\vcvarsall.bat"
MSBUILD /v:q C:\Projects\Forums\Forums.sln
MSBUILD /v:q C:\Projects\MainSite.sln
MSBUILD /v:q C:\Projects\Users\UserMgmt.sln
MSBUILD /v:q C:\Projects\Core\Global.sln
PAUSE

Save this as something like BuildAll.bat then whenever you want to build everything just double click this file.

What was that?! Explain (a bit)

To use MSBUILD you must be running the Visual Studio command prompt but by default batch files run in normal compand prompt so line 2 enables all the Visual Studio-ness. Also, I added the /v:q parameter so that MSBUILD wont output every little detail about the build, just the important bits (PASS/FAIL).

To encodeURI or to encodeURIComponent?

Solved a bug today whilst encoding in JavaScript a URL that contained a certain special character: the hash character #.

I found a generated querystring was not working correctly because many of the params were not being passed to the server somehow. I was generating a link like so: var link = 'http://www.britishdeveloper.co.uk?link=' + encodeURI(url) + '&userID=232';

I was quite pleased with myself remembering to URL Encode params that are going into a querystring to get around special characters but I had not thought of something... the hash character #!

Say the url being placed in the querystring is '/my page.aspx#comment3' my link was coming out as http://www.britishdeveloper.co.uk?link=/my%20page.aspx#comment3&userID=232.

What's wrong with that?

Well it's not what I was expecting really but it was working up until I got urls with hashes in. As you may or may not know everything proceeding a # in a url is for browsers so your server will ignore everything after it. In this case the userID param was not seen by my server.

encodeURIComponent not encodeURI

For this particular scenario encodeURIComponent was what I needed since:

encodeURI('/my page.aspx#comment3')
//output: /my%20page.aspx#comment2

encodeURIComponent('/my page.aspx#comment3')
//output: %2Fmy%20page.aspx%23comment2

encodeURI is for encoding non-URI special characters from a string so the above example of encodeURI would have been great for appending it like so 'http://www.britishdeveloper.co.uk' + encodeURI(url)

encodeURIComponent is for encoding a string to be fit for a querystring param where characters such as . and # shouldn't really be included as in my above example.

So know your Javascript encoding!

Could not load file or assembly 'msshrtmi' or one of its dependencies

Sometimes after publishing my Azure solution I get a yellow screen of death giving a "System.BadImageFormatException" exception with a description of "Could not load file or assembly 'msshrtmi' or one of its dependencies. An attempt was made to load a program with an incorrect format."

I tried everything to get rid of this msshrtmi complaint: building it again, rebuilding it, cleaning the solution, restarting my computer even and that fixes everything in Windows ever!

Very strange as my newly published Azure solution is fine but my development site is now at the mercy of this mysterious msshrtmi assembly.. whatever the hell that is.

Kill msshrtmi! Kill it with fire!

So it's is an assembly right? Assemblies go in the bin folder... let's look there... There it is! msshrtmi.dll. DELETE IT!

I don't know what it is and I didn't put it there so I deleted it and all is back to normal. Excellent.

How to turn off logging on Combres

I have been using Combres for my .NET app to minify, combine and compress my JavaScript and CSS. So far I have found it awesome.

It really does do everything it claims. Minifing your scripts and CSS, then combines them all so that all the code is sent via one HTTP request (well one for CSS and one for JavaScript). It also handles GZip or deflate compression should the request accept it. It is easy to set up since it is now available through NuGet and using it will make YSlow smile when it scans your site.

Logging

One thing that is annoying though is that Combres seems to log everything it does. "Use content from content's cache for Resource x...Use content from content's cache for Resource y" This is fine in development but unnecessary in production so I wanted to turn it off but couldn't find how to do this in any documentation.

The way I managed to turn off logging was to find the line in the web.config that combres put in that looks like this:

<combres definitionUrl="~/App_Data/combres.xml" logProvider="Combres.Loggers.Log4NetLogger" />

You simply need to remove the logProvider so it looks like this:

<combres definitionUrl="~/App_Data/combres.xml" />

If you still want logging on your development environment you can simply remove the logProvider attribute in a web.config transform.

Export and back up your SQL Azure databases nightly into blob storage

With Azure I have always believed, if you can do it with the Azure Management Portal then you can do it with a REST API. So I thought it would be a breeze to make an automated job to run every night to export and back up my SQL Azure database into a BACPAC file in blob storage. I was suprised to find scheduling bacpac exports of your SQL Azure databases is not documented in the Azure Service Management API. Maybe it is because the bacpac exporting and importing is in beta? Nevermind. I successfully have a worker role backing up my databases and here's how:

It is a REST API so you can't use nice WCF to handle all your POST data for you but there is a trick still to avoid writing out all your XML parameters by hand and instead strong typing a few classes.

Go to your worker role or console application and add a service reference to your particular DACWebService (it varies by region):

• North Central US: https://ch1prod-dacsvc.azure.com/DACWebService.svc
• South Central US: https://sn1prod-dacsvc.azure.com/DACWebService.svc
• North Europe: https://db3prod-dacsvc.azure.com/DACWebService.svc
• West Europe: https://am1prod-dacsvc.azure.com/DACWebService.svc
• East Asia: https://hkgprod-dacsvc.azure.com/DACWebService.svc
• Southeast Asia: https://sg1prod-dacsvc.azure.com/DACWebService.svc

Once you import this Service Reference you will have some new classes that will come in handy in the following code:

//these details are passed into my method but here is an example of what is needed
var dbServerName = "qwerty123.database.windows.net";
var dbName = "mydb";
var dbUserName = "myuser";
var dbPassword = "Password!";

//storage connection is in my ServiceConfig
//I know these the CloudStorageConnection can be obtained in one line of code
//but this way is necessary to be able to get the StorageAccessKey later
var storageConn = RoleEnvironment.GetConfigurationSettingValue("Storage.ConnectionString");
var storageAccount = CloudStorageAccount.Parse(storageConn);

//1. Get your blob storage credentials
var credentials= new BlobStorageAccessKeyCredentials();
//e.g. https://myStore.blob.core.windows.net/backups/mydb/2012-05-22.bacpac
credentials.Uri = string.Format("{0}backups/{1}/{2}.bacpac",
    storageAccount.BlobEndpoint,
    dbName,
    DateTime.UtcNow.ToString("yyyy-MM-dd"));
credentials.StorageAccessKey = ((StorageCredentialsAccountAndKey)storageAccount.Credentials)
                                   .Credentials.ExportBase64EncodedKey();

//2. Get the DB you want to back up
var connectionInfo = new ConnectionInfo();
connectionInfo.ServerName = dbServerName;
connectionInfo.DatabaseName = dbName;
connectionInfo.UserName = dbUserName;
connectionInfo.Password = dbPassword;

//3. Fill the object required for a successful POST
var export = new ExportInput();
export.BlobCredentials = credentials;
export.ConnectionInfo = connectionInfo;

//4. Create your request
var request = WebRequest.Create("https://am1prod-dacsvc.azure.com/DACWebService.svc/Export");
request.Method = "POST";
request.ContentType = "application/xml";
using (var stream = request.GetRequestStream())
{
    var dcs = new DataContractSerializer(typeof(ExportInput));
    dcs.WriteObject(stream, export);
}

//5. make the POST!
using (var response = (HttpWebResponse)request.GetResponse())
{
    if (response.StatusCode != HttpStatusCode.OK)
    {
        throw new HttpException((int)response.StatusCode, response.StatusDescription);
    }
}

This code would run in a scheduled task or worker role to be set for 2am each night for example. It is important you have appropriate logging and notifications in the event of failure.

Conclusion

This sends off the request to start the back up / export of database into a bacpac file. The success of this is no indication that the back up was successful, only the request submition. If your credentials are wrong you will get a 200 OK response but it the back up will fail silently later.

To see if it has been successful you can check on the status of your exports via the Azure Management Portal, or by waiting a short while and having a look in your blob storage.

I have not covered Importing because, really, exporting is the boring yet important activity that must happen regularly (such as nightly). Importing is the one you do on the odd occassion when there has been a disaster and the Azure Management Portal is well suited to such an occassion.

How to get Azure storage Account Key from a CloudStorageAccount object

I have a CloudStorageAccount object and I want to get the AccountKey out of it. Seems like you should be able to get the Cloud Storage Key out of a CloudStorageAccount but I did struggle a bit at first.

I first used the CloudStorageAccount.FromConfigurationSetting(string) method at first and then played about in debug mode to see if I could find it.

I then found that that method doesn't return the correct type of object which left me unable to find my Azure storage access key. I then tried the same thing but using CloudStorageAccount.Parse(string) instead. This did have access to the Azure storage access key.

//this method of getting your CloudStorageAccount is no good here
//var account = CloudStorageAccount.FromConfigurationSetting("StorageConnectionStr");

//these two lines do...
var accountVal = RoleEnvironment.GetConfigurationSettingValue("StorageConnectionStr");
var account = CloudStorageAccount.Parse(accountVal);

//and then you can retrieve the key like this:
var key = ((StorageCredentialsAccountAndKey)account.Credentials)
          .Credentials.ExportBase64EncodedKey();

It is strange that CloudStorageAccount.FromConfigurationSetting doesn't give you access to the account key in your credentials but CloudStorageAccount.Parse does. Oh well, hope that helps.

Set maxlength on a textarea

It's annoyed me for quite a while that you can set a maximum length on an <input type="text" /> but not on a textarea. Why? Are they so different?

I immediately thought I was going to have to write some messy JavaScript but then I learned that HTML5 implements maxlength on text areas now and I'm only considering modern browsers! Wahoo!

Then I learnt that IE9 doesn't support it so JavaScript it is...

JavaScript textarea maxlength limiter

What I have done that works well is bind events keyup and blur on my text area to a function that removes characters over the maxlength provided. The code looks like this:

$('#txtMessage').bind('keyup blur', function () {
    var $this = $(this);
    var len = $this.val().length;
    var maxlength = $this.attr('maxlength')
    if (maxlength && len > maxlength) {
        $this.val($this.val().slice(0, maxlength));
    }
});

Conclusion

It works quite well because if the browser already supports maxlength on a textarea there will be no interruption because the value of the textarea will not go over that maxlength.

The keyup event doesn't fire when the user pastes text in using the mouse but that is where the blur event comes in. Also, an enter click makes a new line on a textarea so the user has to click the submit button (blurring the textarea).

Beware though that this is for usability only; a nasty user could easily bypass this so ensure you are checking the length server side if it is important to you.

jQuery - Don't use bind and definitely don't use live!

If you use jQuery you have almost certainly used the .click(fn) event. You may know that just calls .bind('click', fn). You may have used live(). You may know that live() is weird and buggy and inefficient. You may have heard you should not use it in favour of .delegate(). You may have heard of the new .on(). But which is better? bind vs live vs delegate vs on?

Take the following html:

<div id="myContainer">
    <input type="button" id="myBtn" value="Click me!" />
</div>
<script type="text/javascript>
    $('#myBtn').click(doSomething);
</script>

I have a button that has a javascript function called doSomething attached to it. This works fine until I dynamically replace the inner HTML of the div myContainer with a new button (with same ID etc). doSomething will no longer be attached to the new myBtn button so it will not be called when the button is clicked.

FYI, $('#myBtn').click(doSomething); is just shorthand for writing $('#myBtn').bind('click', doSomething);

So you can change the JavaScript code above to $('#myBtn').live('click', doSomething); and it will still work even when the button is brought in or generated dynamically. Up until now I have found that the live function uses magic to just make it all work even after ajax abuse and therefore it is better.

However, recently (in a more complex implementation) I found it was causing some undesired behaviour so I had a dig into it. Turns out live() is buggy and badly performing and has actually been deprecated as of jQuery v1.7 so do not use live! What should you be using for this type of functionality then?

Well, delegate has been the popular replacement since it attaches the method once to a selected container but still targets the inner element as bind or click would. The importance is two fold:

1. The functionality is not wastefully attached to each element matched and instead just once to the containing element
2. Dynamically added items that match the selector will still fire the event since the event is not attached to this element, it is attached to the container that has remained static

In fact live does the same as delegate but it's containing element cannot be defined, it is the whole document which, if you have a deep DOM, finding the originating element using the selector could cause it to search a long way. Lame... In fact, I found bugs with it and there are other details which mean you should use delegate instead. I say should because there is a new cool kid on the block.

So what is better than bind, live and delegate?

You should use .on(). All the cool kids are doing it. Want me to name drop users of on? Well, ME! Perhaps more famous in the JavaScript world is jQuery, and they use it! If you look at the jQuery library bind, live and delegate all just call on as of jQuery v1.7+

So my JavaScript code above should change to:

Bind and click are still fine in my opinion as nice little shortcuts but only when using it them to attach a function to one specific element and only when you are not attaching to dynamic objects. If you are attaching to, say, multiple <li>’s in a <ul> you should use on() instead to attach the event to the <ul> and target the event to the <li>’s. This way there is only one function and multiple references to it rather than creating the function once for each of the <li>’s.

What to do with LastIndexOf unexpected ArgumentOutOfRangeException behaviour

Using string.LastIndexOf(char value, int startIndex, int count); started giving me some behaviour I wasn't expecting when it started giving me an ArgumentOutOfRangeException Exception with a description of: "Count must be positive and count must refer to a location within the string/array/collection."

Let me give you an example:

var message = ".NET is unusually faultless!";
var maxSearch = 16;
var count = message.LastIndexOf('l', 0, maxSearch);
var newMsg = message.Substring(0, count);

This should work right? What could be wrong with this? Well according to IntelliSense "Reports the index position of the last occurrence of the specified Unicode character in a substring within this instance. The search starts at a specified character position and examines a specified number of character positions." Hmm.. Okay. And the count parameter that I am getting wrong? "The number of character positions to examine." Seems legit.

I decided to disassemble .NET to have a peep at what's going on internally... Have I found a bug in .NET?! Can't tell because the method is extern, so I cannot look at it. I instead did some experimenting and worked it out.

How to properly use LastIndexOf

Turns out I was just using it incorrectly and blaming my tools. Although I am convinced some blame lies with IntelliSense for forgetting to mention that LastIndexOf searches backwards through the string! Should I have known that? I don't know. Anyway this is what I should have written:

var message = ".NET is unusually faultless!";
var maxSearch = 16;
var count = message.LastIndexOf('l', maxSearch, maxSearch);
var newMsg = message.Substring(0, count);

The startIndex parameter should be at the last point you want to search backwards from. The count then specifies the amount of chars for your search to go back through.

Maybe I'm just being stupid or maybe it is just that Console.WriteLine(newMsg);