Ignoring ReSharper Code Issues in Your New ASP.NET MVC 3 Application
ReSharper is a great tool for identifying problems with your code. Simply right-click on any project in the Solution Explorer and select Find Code Issues. After ReSharper analyzes all the files, you’ll see a window with several categories of issues including “Common Practices and Code Improvements”, “Constraint Violations”, and “Potential Code Quality Issues”.
Unfortunately, when you create a new ASP.NET MVC 3 application in Visual Studio 2010, Resharper will find thousands of code issues before you even start coding.
Most of these “issues” are in jQuery and Microsoft’s AJAX libraries, and your average developer is not going to go around adding semicolons all day when they have real work to do. So we need to tell ReSharper to ignore these known issues somehow.
It would be nice if ReSharper allowed you to ignore files using file masks, but it doesn’t. You must specify each file or folder individually. Go to ReSharper->Options…->Code Inspection->Settings. Click Edit Items to Skip.
My first instinct was to lasso or shift-click to select all the jQuery scripts, but this is not allowed! I certainly wasn’t going to bounce back and forth between dialog windows a dozen times just to add each file.
Luckily this is ReSharper, and we can move all the script files into another directory and update references automatically. Select all the jQuery scripts in the Scripts folder simultaneously, right-click, and go to Refactor->Move. Create a new jquery folder under Scripts and click Next.
Now you can go back into the ReSharper options and add this folder to the list of items to skip.
Move Microsoft’s script files into their own folder, and tell ReSharper to ignore these as well. I’m also using modernizr so I exluded the two modernizr scripts individually.
Find Code Issues again and things should look much better. I’ve only got 25 issues now.
With the help of ReSharper’s refactoring capabilities I was able to get this down to one issue in just a few minutes. Now you can get on with your project without having to mentally filter out a bunch of noise in the Inspection Results window.
Happy coding!
An HTML5 Music Visualizer for Dev:Unplugged
HTML5 is Here
Although HTML5 is still in development, the latest generation of popular browsers (those released within the past month or so) support a surprisingly consistent set of HTML5 features. This allows developers to start seriously targeting the future standard and taking advantage of its many benefits.
The Contest
Microsoft is currently running a contest called {Dev:Unplugged} that gives Web developers the opportunity to showcase their HTML5 skills. Entrants have the option of creating a game or music-related site, and compete for some awesome prizes. On May 9, an expert team of judges will start evaluating entries based on several criteria such as creativity, quality, and fit with the contest theme.
My Entry: html5beats.com
What it is
html5beats is a music visualizer that generates real time animations that respond to the beat of the music. In the past you had to use Flash or embedded media players to accomplish this. With HTML5 you can do it with JavaScript and markup alone.
How it works
To synchronize audio and video, you must have access to the raw audio data. Unfortunately, browsers don’t offer provide this access in a consistent way (and some don’t offer it at all). I wrote a small C# program that preprocesses the sound files and I add the output (RMS amplitude) to a JavaScript file. It doesn’t need to be high resolution (8 bit, 40Hz) so it works out to only about 20KB per song. At first I thought I invented this method, but I Googled around and discovered that someone else beat me to it. Nevertheless, it works well in practice and provides interesting results.
Features
Cross-browser compatibility
The following browsers are officially supported:
- Internet Explorer 9 (recommended)
- Chrome 10
- Opera 11
- Firefox 4
You can try other browsers with varying results. Some will trigger a compatibility message, while others (like Firefox 3.6) will mostly work, but the site won’t look as good.
Full screen mode
The HTML5 canvas does not explicitly support full screen. I solve this problem by using a second canvas that fills the entire page. The image from the smaller main canvas is copied to the larger one every frame. This may sound inefficient, but it performs well in all my tests.
Lyrics
This feature displays lyrics as the song plays, and can be turned on or off. Although the canvas supports text directly, drawing straight to the canvas would interfere with some of the inter-frame effects I’m using. Therefore, I position a div element over the canvas and change its inner text dynamically.
Pinned site features
Internet Explorer 9 offers a great new feature called “pinned sites” that provide Windows 7 desktop integration. I’ve taken advantage of several pinned site features that enhance the user experience under IE9.
Feature detection and discoverability
If you’re browsing with IE9, html5beats will detect it and prompt you to try pinning the site. If you don’t like seeing this prompt you can close it. Pinning your site adds a high-quality icon to the taskbar and gives you access to additional functionality.
Jump List
Right-clicking the taskbar icon shows a Jump List with tasks that can take you directly to a specific page within the site, even if the browser isn’t currently open.
Thumbnail Toolbar
This is one of the coolest aspects of pinning the site. Hovering over the taskbar reveals playback buttons so you can play, pause, and navigate songs even when the browser doesn’t have focus.
Update: Previous Track and Next Track buttons have been added for additional control of the player.
CSS3
Until now, effects like rounded corners, shadows, and translucency were only available through browser-specific features, custom images, and elaborate CSS trickery. CSS3 makes those techniques obsolete. html5beats exploits CSS3 to improve the aesthetics of the main UI.
Using the Code
For now I’m disallowing use of the code, mainly to prevent someone from using it in a competing entry. After the contest ends I plan on cleaning it up a bit and releasing it under an open-source license.
Please Consider Supporting the Site with Your Vote
In addition to a earning a high score from the judges, winning requires votes from the community. If you like my entry, please vote for it today… there’s only one week left! Also, look forward to new features and updates in the coming days – this is the home stretch.
Profiling Built-In JavaScript Functions with Firebug
Firebug is a Web development tool for Firefox. Among other things, it lets you profile your JavaScript code to find performance bottlenecks.
To get started, simply go to the Firebug Web site, install the plugin, load a page in Firefox and activate Firebug. Click the Profile button under the Console tab once to start profiling, and again to stop it. Firebug will display a list of functions, the number of times they were called, and the time spent in each one.
For example, here is a page that repeatedly draws a red rectangle and blue circle on the new HTML5 canvas:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Profiling Example</title>
</head>
<body>
Let’s assume your code is taking a long time to execute. Running the profile produces these results:
Click to enlarge
This isn’t very useful because only user-defined functions show up. There is only one significant function here so there’s nothing to compare. If there were some way to profile built-in JavaScript functions, we might get a better idea of which parts of the code are running slowly.
Note: This is a contrived example written to illustrate a point. It would be just effective, and probably a better design overall, to extract two methods named drawRectangle() and drawCircle(). See Extract Method.
As a workaround, you could wrap some of the native functions and call the wrappers in your program code, like this:
function drawShapes() {
var canvasElement = document.getElementById('canvasElement');
var context = canvasElement.getContext('2d');
context.fillStyle = 'rgb(255, 0, 0)';
// Draw a red rectangle many times.
for (var i = 0; i < 1000; i++)
{
fillRect(context, 30, 30, 50, 50);
}
context.fillStyle = 'rgb(0, 0, 255)';
// Draw a blue circle many times.
for (var i = 0; i < 1000; i++)
{
context.beginPath();
context.arc(70, 70, 15, Math.PI * 2, 0, true);
context.closePath();
fill(context);
}
}
function fillRect(context, x, y, w, h) {
context.fillRect(30, 30, 50, 50);
}
function fill(context) {
context.fill();
}
But that would impact your design and create unnecessary overhead. Ideally, you’ll want a solution that’s only active during debugging and doesn’t affect your production script. One way to do this is to write overrides for the native functions and store them in their own .js file (don’t forget to reference the script file in the HTML page):
if (window.console.firebug !== undefined)
{
var p = CanvasRenderingContext2D.prototype;
p._fillRect = p.fillRect;
p.fillRect = function (x, y, w, h) { this._fillRect(x, y, w, h) };
p._fill = p.fill;
p.fill = function () { this._fill() };
}
What we’re doing here is saving the original function by assigning it to another function with the same name, prefixed with an underscore. Then we’re writing over the original with our own function that does nothing but wrap the old one. This is enough to make it appear in the Firebug profiling results.
Click to enlarge
The beauty of this approach is that it only runs when the Firebug console is turned on. When it’s not, the conditional check fails and the code block is not executed. The check also fails in other browsers such as IE9 and Chrome 11 beta, which is exactly what we want.
One disadvantage is that you have to write a separate function for each native function you want to override. In the above example, a significant amount of time is probably spent in context.arc(), but we didn’t override it so there’s no way to tell. It may be possible to override and wrap every function in a specified object automatically, but I haven’t tried that yet. For now, I’ll leave it as an exercise for the reader.
Workaround for NullReferenceException in DBComparer
DBComparer 3.0 is a great tool if you want to synchronize your SQL Server database environments and don’t have hundreds of dollars to spend on Red Gate’s SQL Compare. It’s simple to use and free.
dbcomparer.com/
I used it for a couple of weeks without any problem until one day when I tried to compare with a particular server and it crashed:
Looking at the error message, we can deduce that the WriteRecentList() function saves the names of the servers you have typed in the recent servers list. This is sort of like the recent files list found in some applications.
SettingsBase is part of the .NET Framework, and this part of the code is probably used to persist application settings. A little digging around on the MSDN library reveals this:
Specific user data is stored in a file named user.config, stored under the user’s home directory. If roaming profiles are enabled, two versions of the user configuration file could exist. In such a case, the entries in the roaming version take precedence over duplicated entries in the local user configuration file.
A look in the user.config file confirms our theory that this is where the list of recent servers are stored. However, DBComparer is only designed to support 10 recent server names (5 on each side of the comparison). Any more than that and it blows up.
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<userSettings>
<DBCompare.Properties.Settings>
<setting name="RecentServerName11" serializeAs="String">
<value>server1</value>
</setting>
<setting name="RecentServerName12" serializeAs="String">
<value>server2</value>
</setting>
<setting name="RecentServerName13" serializeAs="String">
<value>server3</value>
</setting>
<setting name="RecentServerName14" serializeAs="String">
<value>server4</value>
</setting>
<setting name="RecentServerName15" serializeAs="String">
<value>server5</value>
</setting>
<setting name="RecentServerName21" serializeAs="String">
<value>server6</value>
</setting>
<setting name="RecentServerName22" serializeAs="String">
<value>server7</value>
</setting>
<setting name="RecentServerName23" serializeAs="String">
<value>server8</value>
</setting>
<setting name="RecentServerName24" serializeAs="String">
<value>server9</value>
</setting>
<setting name="RecentServerName25" serializeAs="String">
<value>server10</value>
</setting>
</DBCompare.Properties.Settings>
</userSettings>
</configuration>
As a workaround until this bug is fixed, you can delete some or all of the server names in the value tags to make room for more and prevent the error.
Same Markup, Same Browser, Different Results
Here is a simple HTML5 page I created:
<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8" /> <title>Inconsistent Rendering</title> </head> <body> <span style="px; overflow: visible; background-color: Green;"> <h1>This is a test.</h1> </span> </body> </html>
And here is that page rendered in Internet Explorer 8. In one case it’s being served on my laptop, and the other on the local intranet.
The markup, the Web servers, and the browser are all set up 100% the same. These should be identical, shouldn’t they? What’s the problem? The answer is Compatibility View.
Compatibility View is a “feature” of Internet Explorer that causes it to ignore modern Web standards. That would be fine, except Compatibility View settings vary by zone, and different zones have different defaults. Also, the Compatibility View button in the address bar isn’t always available, which means there’s no visual indicator as to what mode you’re in, and you can’t change modes for the current page easily.
Compatibility View settings can be accessed in the Tools –> Compatibility View Settings menu, but if you’ve developed a standards compliant intranet site, you need a better fix than simply asking each individual user to reconfigure their browser. Group Policy is one option, but there is a much simpler solution. Just add the following meta tag to your pages, and it will force IE 8 to use the !DOCTYPE declaration in the page to determine the rendering mode.
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE8" />
If you’re experiencing rendering inconsistencies with the same markup being served from different environments, have a look into Compatibility View. It just might be the culprit.
Mercurial HTTP Error 500: Access is denied on 00changelog.i
Today I created a new Mercurial repository on a Windows server. I cloned it, made some changes, tried to push, and was greeted with this:
C:\myapplication>hg push
pushing to servername/myapplication
searching for changes
abort: HTTP Error 500: .hg\store0changelog.i: Access is denied
My user account had write permission to the myapplication folder on the server, and the odd thing is that I’ve created repositories there before and never had a problem pushing changes. I compared 00changelog.i to the same file in another repository that was working. Turns out I was using anonymous authentication and IUSR was missing write permission. I gave full control to IUSR on hg\store folder and…
C:\myapplication>hg push
pushing to servername/myapplication
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 114 changes to 114 files
Success!
If you’re having problems pushing to a central server with Mercurial, make sure the IIS anonymous authentication account (IUSR or IUSR_MachineName) you have write permission to the hg\store folder and subfolders in your repository.
Conditional Validation with Data Annotations in ASP.NET MVC
In the simple blog engine I’m building, I encountered a scenario where I wanted to display different UI elements depending on whether the user was logged in:
Not logged in
Logged in
When the user is authenticated, their name and email is known, so it’s unnecessary to display them on the comment input form. While it would be possible to hide just those fields, I decided to make separate partial views and display them in the Post view with the following code:
<%
if (Model.AllowComments)
{
var commentControlName = Request.IsAuthenticated ? AuthenticatedCommentFormControl" : "CommentFormControl";
Html.RenderPartial(commentControlName, new DotBlog.Models.ViewModels.CommentViewModel(Model.PostId));
}
%>
This is the view model I used for both partial views:
public class CommentViewModel
{
...
[Required]
[StringLength(50)]
[DisplayName("Name")]
public string CommenterName { get; set; }
public DateTime Date { get; set; }
[Required]
[StringLength(100)]
public string Email { get; set; }
[StringLength(100)]
[DisplayName("Web Site")]
public string WebSite { get; set; }
[Required]
[StringLength(1024)]
[DisplayName("Comment")]
public string CommentText { get; set; }
...
}
As you can see, I’m using data annotations to enforce required fields and string lengths. The problem is, even though the name and email aren’t always displayed, they are still required. I needed a way to validate certain fields conditionally. Here are the options I came up with:
- Stop using data annotations and find a different solution for validation
- Use two different view models: one for each partial view
- Use actual conditional data annotations, like the library built by Simon Ince.
- When the form is posted, remove the fields from the model state so they’re not validated.
Let’s look at each of these individually:
Stop Using Data Annotations
Data annotations are not the only way to specify validation rules, but they’re easy to implement. xVal was fine for ASP.MVC 1.0, but is now deprecated. Custom validation code with ModelState.AddModelError() is flexible, but requires extra work.
Use Two Different View Models
Since I’m using two partial views for the comment form (one for authenticated users and one for guests), I could use a dedicated view model for each. One would omit the data annotations on name and email and therefore not cause any validation problems. This was my original implementation, but lead to unnecessary code duplication and other design problems.
Use Conditional Data Annotations
Simon Ince has built a cool library for conditional annotations that allows you to write code like this:
public class ValidationSample
{
[RequiredIf("PropertyValidationDependsOn", true)]
public string PropertyToValidate { get; set; }
public bool PropertyValidationDependsOn { get; set; }
}
Conditionally Remove Fields from the Model State in the Controller
In the end, this is the solution I went with. The controller executes this code when the form is posted:
if (Request.IsAuthenticated)
{
...
// We don't need to validate user fields if user is logged in.
ModelState.Remove("CommenterName");
ModelState.Remove("Email");
}
By removing the fields from the model state, it won’t be invalid when they are missing. This method is simple and avoids adding additional dependencies.
Entity Framework StoreGeneratedPattern Bug Persists
I’m using System.Data.SQLite v1.0.66.0 with Entity Framework 4.0 and Visual Studio 2010. I designed some tables in SQLite and generated an Entity Data Model from those tables. One of them (we’ll call it Person for the sake of argument) has an autogenerated integer primary key. I manually set the StoreGeneratedPattern property to Identity in the designer, but when I started creating new rows in the database I encountered a problem.
I create new Person entities with a dummy PersonID of -1. The first row inserts fine, but instead of generating a new ID it uses the dummy value. That means when I insert the second row, it fails:
Abort due to constraint violation
PRIMARY KEY must be unique
I did a little Googling and realized I’m not the only person experiencing this:
- EF4: Bug in StoreGeneratedPattern SSDL | geek#
- edmx designer properties does not set StoreGeneratedPattern=”Computed” in SSDL
- StoreGeneratedPattern in Entitiy framework – Stack Overflow
It seems there is a bug in which the StoragePattern property is not updated in the SSDL when you change it in the designer, even though the CSDL is.
The impact of this is that you have to open the .edmx file in the XML editor and manually add the StorageGeneratedPattern property to the definition for your entity in the StorageModels section:
<EntityType Name="Person">
<Key>
<PropertyRef Name="PersonID" />
</Key>
<Property Name="PersonID" Type="integer" Nullable="false" StoreGeneratedPattern="Identity" />
<Property Name="Name" Type="nvarchar" Nullable="false" MaxLength="50" />
<Property Name="Age" Type="integer" Nullable="false" />
</EntityType>
Even worse, you’ll have to do this for every identity column every time you update the model from the database because the property gets clobbered. The workaround does work, technically, but it’s a major nuisance during development when things change often.
Identity columns are not uncommon, which means that this issue should have been uncovered early during testing. Why didn’t Microsoft fix it right away? According to some claims, it’s been around since EF 1.0. In a couple of weeks I’m starting a new job where they use NHibernate. It will be interesting to compare it to EF 4.0 and see if I run into the same kind of bugs. Perhaps it will also help to wean me off graphical designers altogether.