Zenji Web Development

ASP.NET MVC ActionFilters and Response.Redirect

Posted by Jason on December 19, 2008 at 5:28 pm

There is an issue with using the following code in an action filter:
filterContext.HttpContext.Response.Redirect(loginUrl, true);
which is a bit of code quite common in an authentication filter. The problem is it will throw a ThreadAbortException as soon as you put your code on a live site resulting in the error page for anyone who is not logged in. This is probably not what you want since you are attempting to redirect them to the login page.

Now it is a little unfair to say that it’s an issue because that is the intended functionality. But it doesn’t fit well with MVC controllers, especially since Microsoft’s official suggestion is to set the endResponse flag to false. That is just downright misleading since your controller action (which the filter just decided you can’t access) is still executed after the filter fails authentication - resulting in the action code being executed anyway whilst you see the login screen on the browser and assume it all went swimmingly! Meanwhile those files that this user shouldn’t have access to got deleted.

Yeah, that’s what I just did during testing whilst proving to myself that you can’t fake the URL as a non-registered user. Imagine my surprise. It’s true that the chances of a malicious user actually working out the URL might be low, but that’s no reason to leave the door open.

Oh, and your unit tests probably won’t catch this because the filters don’t get executed by the unit tests. But I digress…

To cut a long story short, this bit of code in your base controller (assuming you have one, otherwise stick in in all of the controllers) will prevent the issue:

        protected override void OnException(ExceptionContext filterContext)        {            if (filterContext.Exception is ThreadAbortException)            {                filterContext.ExceptionHandled = true;            }        }

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Posted in ASP.NET MVC, Web, Gotchas, Software Development by Jason @ 5:28 pm

Maximum Request Length Exceeded

Posted by Jason on December 11, 2008 at 9:52 am

It’s hard to believe how badly this is handled in IIS. Admittedly I’ve only tried it in IIS 6, but I see no evidence that it gets any better in IIS 7.

So here’s the problem - you create a website that allows the upload of images (or any file types for that matter). It’s very likely you’re going to want to limit the size of those uploads or you’ll end up in a world of pain when your users go and use up all your disk space. By default IIS allows upload sizes of 4Mb which is ample for image purposes. However, if someone uploads a file above that size you’re likely to want to notify them by telling them gently they’re an idiot for not reading the note above the file input field and then allow them to reselect a file.

But you can’t because the requests never gets to your page. IIS simply drops the request and seems to respond with nothing at all. That leaves the user looking at a ‘Web site could not be found’ error, which is misleading and just plain wrong. (more…)

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Posted in IIS, Web by Jason @ 9:52 am

Creating Strongly-Typed Views in ASP.NET MVC Beta

Posted by Jason on December 5, 2008 at 12:42 pm

One of the big problems with the early adoption of any framework is the documentation. No books are released yet, if they are ever going to be, and so turning to Google is your best bet. In fact it’s your only option and my own preference is using Google over books anyway.

But frameworks change during development and you come across the issue that all of the top hits for your query are based on previous versions. When that previous version did it differently you’re stuck! I had this problem today when trying to create strongly-typed views. I love strongly-typed anythings, but I’m just a sucker for having a project that is more likely to work when another developer makes an edit and doesn’t bother fully checking the effects of their changes. It’s another safety net, and I’m a sucker for safety nets as well.

So, this is how I did it in bite-sized chunks. First the controller function:
public ActionResult Index() { var ContentObject = new ContentClass() return View(ContentModel.Load(ContentObject)); }
Next I created a new view by right-clicking the above method (bear in mind that I’m using Visual Studio 2008) and checking the ‘Create a strongly-typed view’ before entering the full name of the object type (ContentClass). That produces an aspx.cs which looks something like this:
public partial class Index : ViewPage<ContentClass>
So far so good, but where I really came unstuck was actually using this in the view. Turns out it’s simpler than ever. All you need to use is the ViewData.Model parameter, which is automatically typed to whatever you set the view up as previously:
<% foreach (var portfolio in ViewData.Model.Portfolios) { %> <p><%= portfolio.ID %></p> <% } %>
All that I have to do now is pass that through to a UserControl. I’m assuming I can strongly-type those as well. We shall see.

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Posted in ASP.NET MVC, Web, Software Development by Jason @ 12:42 pm

Deploying ASP.NET MVC Applications

Posted by Jason on November 28, 2008 at 10:56 pm

Now I’m a huge fan of the ASP.NET MVC framework. So much so that I have taken to porting across applications already started using the Castle Monorail framework. Why? Well, there’s just a nice, warm, supported feeling when using a framework that is built-in to your chosen development platform.

Or at least that’s what you’d think. You know how it is - you get it all working on your lovely development machine and then once the decision has been made on where to host the final result, you upload your application and…bang…

HttpException (0x80004005): The incoming request does not match any route.

Oh yes, that works so well.

Suddenly that belief that, finally, someone has produced a framework which is so nicely integrated with your target platform comes crashing down around your head as you weep softly into your keyboard. No, ASP.NET MVC is not actually supported on anything under IIS7. Does your host offer IIS7 at the moment? I guess not.

Now don’t get me wrong, it does work on IIS6 but you have to mangle it a bit and unless you pay a fortune each month for access to your own virtual server then you’re likely to lose those pretty urls. That’s not the same as being supported. For those that have spent the last two hours Googling and still getting the same problem, here is the man with the answer:

http://haacked.com/archive/2008/11/26/asp.net-mvc-on-iis-6-walkthrough.aspx

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Posted in ASP.NET MVC, Web by Jason @ 10:56 pm

The trouble with the right-alignment of input fields

Posted by Jason on July 11, 2008 at 11:32 am

Everyone knows that when you have a text box which accepts a number, it should automatically right-align the text content. Well maybe not everyone, but accountants certainly do and if you’re writing an application for an accountant it just won’t look right unless the values are right-aligned.

Simple, I thought - text-align:right in the CSS and the jobs a good ‘un. Well yes, you would think so. The fact of the matter is that text-align:right is only supposed to apply to block level elements (according to the CSS2 specs), although it isn’t quite implemented that way in all browsers. So, add display:block in there as well just to be on the safe side:

Left Align: <input style=”padding: 0px; text-align: right; display: block” type=”text” />

Right Align: <input style=”padding: 0px; display: block” type=”text” />

Job done! Well, not quite if you are viewing this in Internet Explorer 7. Click in the input field which is aligned to the right and no cursor displays at all! I must be tired today because this took me ages to work out and I found no reference to it anywhere in the web. For some reason the cursor is there - it’s just off to the right a little too far. I say ’some reason’ when I now know that the actual reason is that the padding is set to 0px. The reason for this happens to be because it has inherited the property from other elements in my form layout, but in this example I have added it specifically. Add a little padding to the right and hey presto:

Left Align: <input style=”padding: 0px 1px 0px 0px; text-align: right; display: block” type=”text” />

Right Align: <input style=”padding: 0px 1px 0px 0px; display: block” type=”text” />

That’s just strange. Zero padding displays the cursor on the left, but not the right. Except in Firefox, which just shows it correctly in either case.

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Posted in Web, Gotchas, Software Development by Jason @ 11:32 am

CakePHP and clean URLs

Posted by Jason on July 28, 2007 at 11:39 am

Now don’t get me wrong - I love CakePHP and I know there’s a good reason for the controller/action format of urls. In fact I often find it helps to have a framework that forces that sort of thinking on me all the time since most of the sites I write are more application than website. It’s a bit like the good old days when I was struggling to get my head around the concept of OO after coming from a very procedural background. I could probably have done with a framework then too.

So I do think that it’s great for web applications, but not necessarily for web sites. Clean urls have many touted advantages over controller/action urls for a web site. I’m not sure how many are true (things like Google favouring them seem like a good reason, if that is actually the case) but for me it’s best simply because they are not controller actions. A ‘contact me’ page is a ‘contact me’ page. It’s not really an action on a particular controller in your application. An ‘about’ page is similar - it just seems wrong to say ‘about’ is an action on ‘pages’. Well, it does to me anyway. Whilst I usually write web applications there is almost always a web site component like this to them and I think it’s fine to seperate those two concepts even when they’re on the same site.

Now it’s true that you can write static pages directly to the webroot, but my clients almost always want some management control over those pages. As much as I’d like them to have to come back to me every time they want to change a word it just doesn’t seem particularly fair and just harms my chances of repeat business! All of the other solutions I came across just seemed rather complex and often slightly dodgy. So I came up with a simple solution of my own that works fine.

Basically you add an entry to routes.php for each of these pages:
$Route->connect('/contact/*', array('controller' => 'pages', 'action' => 'contact'));
This will redirect any call to ‘/contact’ to ‘/pages/contact’, but without giving that fact away to the user. It’s true that you can’t now have a controller called ‘contact’ but then you wouldn’t want one anyway (the main reason being controller names should be plural when following the Cake conventions!). You can add as many of these lines as you like. If you end up with more than 2 or 3 you might want to question whether those pages should have been part of a controller!

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Posted in Web, Software Development by Jason @ 11:39 am

Using checkboxes in CakePHP

Posted by Jason on July 3, 2007 at 10:26 pm

Something that’s had me confused for a couple of hours today is using a checkbox in my CakePHP application. I’ve been using the html helper to create the relevant html and was initially confused by the fact that it not only creates the input element but also a preceding hidden input element.
<input type="hidden" name="data[Item][big_rock]" value="0" id="ItemBigRock_" /> <input type="checkbox" name="data[Item][big_rock]" id="ItemBigRock" value="1" />
So I did the best thing I could think of and ignored it, but when I came to creating the form to edit existing values I just ended up getting strange results. The checkboxes seemed to have a life of their own, checking and un-checking at will between post-backs. Google came up with several posts about the general problem most people come across with checkboxes - the fact that they post back nothing if they are not checked, but it took me far too long to actually put the strange hidden input field and this standard behaviour together. In my defence, there is very little documentation on this (that I could find) for CakePHP.
(more…)

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Posted in Web, Software Development by Jason @ 10:26 pm

Setting up CakePHP with fastCGI

Posted by Jason on July 2, 2007 at 11:36 am

I’ve been using CakePHP for quite a while now with no .htaccess issues at all, either running locally or on hosted sites. That all changed last night when I couldn’t get it to work at all on one of my budget hosting sites. Instead of my application all I saw were 500 Internal Server Errors.

I found that the issue was definitely down to one line in the root .htaccess (which was unmodified from the original CakePHP download):
RewriteRule (.*) app/webroot/$1 [L]
Unfortunately my cheaper hosting doesn’t allow me access to the error logs so it was difficult to diagnose the problem. By 11:00 last night I was certainly not in a good mood and no closer to an answer. I managed to Google plenty of references to similar issues but none solved my problem.

This morning I resorted to the hosting company themselves and within an hour they came up trumps! My thanks to Rob at VirtualNames support who not only worked it out, he even changed the file for me!

It looks like the problem is that the mod_rewrite rules don’t like fastcgi, which is the preferred option for this hosting account - it seems to try and redirect the internal URLs for fast cgi causing a rewriting loop. VirtualNames support felt it would probably work if the PHP mode is switched back to module mode, but they also came up with a fix to the .htaccess in the domain folder to (the root .htaccess for the CakePHP installation):
<IfModule mod_rewrite.c> RewriteEngine on RewriteCond %{REQUEST_URI} !^/cgi-bin/ RewriteRule ^$ app/webroot/ [L] RewriteCond %{REQUEST_URI} !^/cgi-bin/ RewriteRule (.*) app/webroot/$1 [L] </IfModule>
This stops it trying to redirect the fastcgi internal access urls, and appears to cure the problem. It looks like the other .htaccess files do not need changing. .htaccess and rewrite rules are still a bit of a black art to me. After this they are going on my list of things to pick up!

I can also recommend VirtualNames as a budget hosting solution should you need one. Their support people actually do…erm…’support’

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Posted in Web, Gotchas, Software Development by Jason @ 11:36 am

Setting up for web development on OS X

Posted by Jason on June 16, 2007 at 4:12 pm

I’ve been slowly working through all of the bits I usually use for web development on my MacBook, attempting to get it set up in a similar way to my PC. No particular reason for that, it’s just what works for me and means I can swap between machines whenever I like - PC for the working week and Mac for out-of-hours seems to be my pattern…

On the whole it has gone fairly smoothly, though it hasn’t been entirely without problems. Here is the detail of what I have set up and where I came across issues. It might help someone if they come from a similar background to me of PC development.
(more…)

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Posted in Web, Software Development by Jason @ 4:12 pm

Google has the right idea

Posted by Jason on September 28, 2006 at 5:22 pm

I envy this guy deeply:

http://steve-yegge.blogspot.com/2006/09/good-agile-bad-agile_27.html

I’ve spent a lot of time recently using Google and Google based technologies (Google Earth, Google Mail, Google Home Pages, Google Analytics, Google Spreadsheets, etc, etc) and I just never fail to be impressed. I didn’t even mention creating my own modules for my Google Home Page which is just a joy. Being a developer of SharePoint Web Parts from time to time I have a view of the ‘other side’ and just how hard it is to get things to work as you want. It’s always too complicated - people just want information and my job of getting that to them is far harder than it should be.

But Google stuff just works! It’s simple, and it JUST WORKS! The way they get to work results in people creating stuff that other people want. It must be the way they work, I can’t see anything else that would cause that effect.

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Posted in Web, Software Development by Jason @ 5:22 pm

Zenji Web Development

Website development and consultancy

ASP.NET MVC ActionFilters and Response.Redirect

Maximum Request Length Exceeded

Creating Strongly-Typed Views in ASP.NET MVC Beta

Deploying ASP.NET MVC Applications

The trouble with the right-alignment of input fields

CakePHP and clean URLs

Using checkboxes in CakePHP

Setting up CakePHP with fastCGI

Setting up for web development on OS X

Google has the right idea

Zenji Web Development is based in York, North Yorkshire, UK and specialises in web application and software development.