ASP.NET MVC JavaScript Routing
- by zowens
Have you ever done this sort of thing in your ASP.NET MVC view?
The weird thing about this isn’t the alert function, it’s the code block containing the Url formation using the ASP.NET MVC UrlHelper. The terrible thing about this experience is the obvious lack of IntelliSense and this ugly inline JavaScript code. Inline JavaScript isn’t portable to other pages beyond the current page of execution. It is generally considered bad practice to use inline JavaScript in your public-facing pages. How ludicrous would it be to copy and paste the entire jQuery code base into your pages…? Not something you’d ever consider doing.
The problem is that your URLs have to be generated by ASP.NET at runtime and really can’t be copied to your JavaScript code without some trickery.
How about this?
Does the hard-coded URL bother you? It really bothers me. The typical solution to this whole routing in JavaScript issue is to just hard-code your URLs into your JavaScript files and call it done. But what if your URLs change? You have to now go an track down the places in JavaScript and manually replace them. What if you get the pattern wrong? Do you have tests around it? This isn’t something you should have to worry about.
The Solution To Our Problems
The solution is to port routing over to JavaScript. Does that sound daunting to you? It’s actually not very hard, but I decided to create my own generator that will do all the work for you.
What I have created is a very basic port of the route formation feature of ASP.NET routing. It will generate the formatted URLs based on your routing patterns. Here’s how you’d do this:
Does that feel familiar? It looks a lot like something you’d do inside of your ASP.NET MVC views… but this is inside of a JavaScript file… just a plain ol’ .js file. Your first question might be why do you have to have that “.toUrl()” thing. The reason is that I wanted to make POST and GET requests dead simple. Here’s how you’d do a POST request (and the same would work with a GET request):
The first parameter is extra data passed to the post request and the second parameter is a function that handles the success of the POST request. If you’re familiar with jQuery’s Ajax goodness, you’ll know how to use it. (if not, check out http://api.jquery.com/jQuery.Post/ and the parameters are essentially the same).
But we still haven’t gotten rid of the magic strings. We still have controller names and action names represented as strings. This is going to blow your mind…
If you’ve seen T4MVC, this will look familiar. We’re essentially doing the same sort of thing with my JavaScript router, but we’re porting the concept to JavaScript. The good news is that parameters to the controllers are directly reflected in the action function, just like T4MVC.
And the even better news… IntlliSense is easily transferred to the JavaScript version if you’re using Visual Studio as your JavaScript editor.
The additional data parameter gives you the ability to pass extra routing data to the URL formatter.
About the Magic
You may be wondering how this all work.
It’s actually quite simple. I’ve built a simple jQuery pluggin (called routeManager) that hangs off the main jQuery namespace and routes all the URLs. Every time your solution builds, a routing file will be generated with this pluggin, all your route and controller definitions along with your documentation. Then by the power of Visual Studio, you get some really slick IntelliSense that is hard to live without.
But there are a few steps you have to take before this whole thing is going to work.
First and foremost, you need a reference to the JsRouting.Core.dll to your projects containing controllers or routes.
Second, you have to specify your routes in a bit of a non-standard way. See, we can’t just pull routes out of your App_Start in your Global.asax. We force you to build a route source like this:
The way we determine the routes is by pulling in all RouteSources and generating routes based upon the mapped routes.
There are various reasons why we can’t use RouteCollection (different post for another day)… but in this case, you get the same route mapping experience. Converting the RouteSource to a RouteCollection is trivial (there’s an extension method for that).
Next thing you have to do is generate a documentation XML file. This is done by going to the project settings, going to the build tab and clicking the checkbox. (this isn’t required, but nice to have).
The final thing you need to do is hook up the generation mechanism. Pop open your project file and look for the AfterBuild step. Now change the build step task to look like this:
The “PathToOutputExe” is the path to the JsRouting.Output.exe file. This will change based on where you put the EXE. The “PathToOutputJs” is a path to the output JavaScript file. The “DicrectoryOfAssemblies” is a path to the directory containing controller and routing DLLs. The JsRouting.Output.exe executable pulls in all these assemblies and scans them for controllers and route sources.
Now that wasn’t too bad, was it :)
The State of the Project
This is definitely not complete… I have a lot of plans for this little project of mine. For starters, I need to look at the generation mechanism. Either I will be creating a utility that will do the project file manipulation or I will go a different direction. I’d like some feedback on this if you feel partial either way.
Another thing I don’t support currently is areas. While this wouldn’t be too hard to support, I just don’t use areas and I wanted something up quickly (this is, after all, for a current project of mine). I’ll be adding support shortly.
There are a few things that I haven’t covered in this post that I will most certainly be covering in another post, such as routing constraints and how these will be translated to JavaScript.
I decided to open source this whole thing, since it’s a nice little utility I think others should really be using.
Currently we’re using ASP.NET MVC 2, but it should work with MVC 3 as well. I’ll upgrade it as soon as MVC 3 is released. Along those same lines, I’m investigating how this could be put on the NuGet feed.
Show me the Bits!
OK, OK! The code is posted on my GitHub account. Go nuts. Tell me what you think. Tell me what you want. Tell me that you hate it. All feedback is welcome!
https://github.com/zowens/ASP.NET-MVC-JavaScript-Routing
