TAG | Open Source
I’ve been focusing more and more on my port of Ling-to-Objects, Jsoq the past few weeks. It’s still in really early stages and I’m not quite sure about it’s actual usefulness but I’m learning a lot about JavaScript and having a ton of fun along the way!
Jsoq deals with arrays a lot. About 95% of it’s use cases involve either looping through, altering, or creating arrays. Having a ton of for loops in my code just seems so… not right. For loops have always seemed dirty to me. They just aren’t elegant enough.
Here is your normal, average, everyday for loop in Javascript.
var array = "1,2,3,4,5,6,7,8,9,10".split(',');
for(var i = -1, l = array.length; ++i < l;) {
alert(array[i]);
}
This works. It’s reliable and gets the message across. But what if we needed to loop over an array and get all the items that matched a condition? Using a for loop the code could look something like:
var array = [ 1, 2, 3, 4, 5, 1, 2, 3, 4 ];
var results = [];
var condition = function(i) { return i%2 == 0; };
for(var itt = -1, len = array.length; ++itt < len;) {
if( condition(array[itt]) ) {
results.push(array[itt]);
}
}
This does work, I’ve written code like this many times before, and while technically there isn’t anything wrong with it I think there is still room for improvement.
Jsoq is going to be handling arrays all over the place so the solution to this problem needs to be simple.
Here’s what I need:
- to loop over an entire collection and perform an action on each item.
- If that action produces a result, the item is to be pushed into an array and returned to after the loop is done
- Also: it needs to be readable, someone else coming along should be able to determine what this thing is doing without too much difficulty. So I had my work cut out for me.
.
A few hours later I had a decent function that I could use to replace a lot of the for loops I had. After some more refactoring I was able to wipe them all out and replace them with calls to enumerateOver(). Here is the latest version from source control:
function enumerateOver(collection, work) {
var result = [], val = [];
if (isArray(collection)) {
try {
for (var i = -1, l = collection.length; ++i < l;) {
result = work(collection[i], i);
if (typeof result !== "undefined" && result != null) {
val.push(result);
}
}
}catch (e) {
if (e != jsoq.$break) throw(e);
}
if (val.length > 0) {
return val;
}
}else {
try {
val = work(collection, 0);
}
catch (e) {
if (e != jsoq.$break) throw(e);
}
if (typeof val !== 'undefined') {
return val;
}
}
return result == null ? [] : result;
}
And here is the code to replace the for loops above, re-written to use enumerateOver()
var results2 = enumerateOver(array, function(i, c) {
return i%2 == 0;
});
So by implmenting this function I was able to come up with a more readable, testable and streamlined codebase. Is this suitable for everyone? Definitely not, but I did it for a few reasons:
- Like I mentioned before. I’ve never been at ease with
forloops and being able to replace them all with calls to a single function was a huge win for me - The normal use-case didn’t fit right. I needed to not only iterate over arrays but also return the results of work performed on those items. Doing this the “regular” way just wouldn’t work (see previous reason)
- I thought this was a fun problem to solve
If you have any feedback, good, bad, or indifferent add a comment!
code · Javascript · jsoq · Open Source
I’ve wrapped up work on v0.4 of the Jsoq Console, and the insanely strenuous release cycle for v0.1 of WhatDidIJustEat.com so I’m starting another side project tonight.
Ever been working with a programming language you’re not 100% familiar with and find yourself wondering:
Is this function a built-in function or in some included library?
What assembly is this class in again?
Can I name my class XXXX without conflicting with another class?
I’ve had these questions recently and found myself annoyed and frustrated to no end (PHP, I’m looking at you) so I’ve decided to build a system to keep track of this stuff for me :D.
The first thing on my list (because it was the easiest) was to do a data dump of all the public classes in the .Net Framework, including the ones in my GAC, and store some metadata for each one in a database table. I’ve just finished this step and thought that this data might be useful, so I’m posting it here.
Currently the fields included in the data dump are:
[namespace] = The namespace that the class exists in (ex: System.Collections.Generic)
[class_name] = The name of the class (ex: StringBuilder)
[assembly_fullname] = The display name of the assembly (ex: mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
[assembly_file] = The full file path to the assembly (ex: C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.dll)
[framework_name] = The framework that uses this class, for this dump they will all be 'Microsoft .Net'
[framework_version] = The framework version that uses this class (ex: v.2.0.50727)
The .sql file takes about 18 seconds to run to completion on my AMD Athlon X2 2.53ghz machine with 4gb of RAM.
If you’re curious about how I generated the .sql file, below is the code I used to find all the classes. It’s not pretty but then again it was just meant to get the data into the database. Just paste the code into a new console app and run it in a command window like so:
[application_name].exe > c:\classes.sql
Or, you can download the .sql file I’ve generated (it will also create the table you need to store the data).
static void Main(string[] args)
{
var dictionary = new Dictionary(){
{ "v2.0.50727", @"C:\Windows\Microsoft.NET\Framework\v2.0.50727" },
{ "v3.0", @"C:\Windows\Microsoft.NET\Framework\v3.0" },
{ "v3.5", @"C:\Windows\Microsoft.NET\Framework\v3.5" },
{ "v???", @"c:\windows\assembly\gac" }
};
var types = new List();
foreach (var pair in dictionary)
{
var path = pair.Value;
var assemblies = Directory.GetFiles(path, "*.dll", SearchOption.AllDirectories);
foreach (string file in assemblies)
{
try
{
Assembly asm = Assembly.LoadFile(file);
foreach (Type t in asm.GetTypes())
{
if (t.IsPublic)
{
Console.WriteLine(String.Format(
"INSERT INTO Classes (" +
"[namespace], " +
"class_name, " +
"assembly_fullname, " +
"assembly_file, " +
"framework_name, " +
"framework_version" +
") " +
"VALUES (" +
"'{0}', " +
"'{1}', " +
"'{2}', " +
"'{3}', " +
"'Microsoft .Net', " +
"'{4}'" +
")",
String.IsNullOrEmpty(t.Namespace) ?
"GLOBAL" :
t.Namespace,
t.Name
.Replace("`1", "")
.Replace("`2", "")
.Replace("`3", ""),
t.Assembly.FullName,
t.Assembly.Location,
pair.Key == "v???" ?
t.Assembly.GetName().Version.ToString() :
pair.Key
));
}
}
}
catch { }
}
}
}
If you found this useful, let me know in the comments!
.NET · Open Source · Programming · SQL
Download the source code mentioned in this blog post.
A few weeks ago on the StackOverflow podcast, something Jeff said got me thinking. Jeff was discussing how the stackoverflow team implemented their route mappings:
Those routes are… the way we implemented them are actually like decorators. Attributes on the methods. - Jeff Atwood (stackoverflow episode #54)
This instantly piqued my interest and I completely zoned out for the rest of the podcast: caught up in working out the details of how I could do this for my own Asp.net MVC projects.
Coming up with the actual attribute code was easy; writing the code to set up all the Routes using only data defined in by the attribute was tricky.
Being new to attributes, and reflection in general, it took me a few hours until I had a very basic demo working. However, I was really starting to like where it was going.
As a side note: There are lot of “helper” classes and objects in the route attribute project (it feels cluttered to me) and the reason I did this was to make the code in AssemblyExtensions.GetRoutes() easier to read.
After a few nights of Mtn Dew and convenience-store cherry-pie I finished the rough code, tests and demo project (included in this blog post) and I was starting to realize that:
- Using the attributes is more declaritive and it feels cleaner
- Having your route information right above your actions is incredibly useful
- I had no more need to switch back and forth between your controller and the Global.asax.cs
How does it work?
All of the real work for the RouteAttribute is done in the AssemblyExtensions class. This class uses extension methods to augment the System.Reflection.Assembly class with two methods: GetControllers() and GetRoutes().
GetRoutes is the only method that is used by other classes, I made GetControllers public for unit testing.
GetRoutes()
GetRoutes’ first order of business is to make a list of data that it will need to build out all the routes for the assembly it was passed. After thats done GetRoutes will loop through the collected route data, build up each route and add it to the dictionary that will eventually be returned.
namespace CodeImpossible.Mvc.Routing
{
public static class AssemblyExtensions
{
public static BindingFlags ActionFlags =
BindingFlags.Instance |
BindingFlags.Public |
BindingFlags.DeclaredOnly;
public static IList<ControllerMetaData> GetControllers(this Assembly assembly)
{
var controllers = assembly.GetTypes().ToList().FindAll(type =>
{
var isValidController = type.IsClass &&
type.IsPublic &&
type.IsSubclassOf<Controller>();
var hasValidActions = type.GetMethods(ActionFlags).ToList().Any(m =>
{
var valid = false;
if (m.ReturnParameter != null && m.ReturnParameter.ParameterType == typeof(ActionResult))
{
valid = m.GetAttributesOfType<RouteAttribute>().Count > 0;
}
return valid;
});
return isValidController && hasValidActions;
}).Select<Type, ControllerMetaData>((t) => new ControllerMetaData(t)).ToList();
return controllers;
}
public static IDictionary<string, Route> GetRoutes(this Assembly assembly)
{
var Routes = new Dictionary<string, Route>();
var data = (from c in assembly.GetControllers()
from a in c.GetActions()
from r in a.Data
select new
{
ControllerName = c.Name,
ActionName = a.Name,
RouteData = r,
RouteParams = a.Params
}).ToList();
foreach (var r in data)
{
var route = new Route(r.RouteData.RoutePath, new MvcRouteHandler());
route.Constraints = new RouteValueDictionary();
route.Defaults = new RouteValueDictionary(new {
controller = r.ControllerName,
action = r.ActionName
});
if (r.RouteData.RequireRouteParams && r.RouteParams.Count() == 0)
{
throw new MissingRouteParameterException("Unknown", r.RouteData.RoutePath);
}
var missingParams = new List<ParameterMetaData>();
if (r.RouteData.RequireRouteParams)
{
missingParams = (from p in r.RouteParams
where r.RouteData.RoutePath.IndexOf("{" + p.Name + "}") == -1
select p).ToList();
}
if (missingParams.Count > 0)
{
var param = missingParams.First();
throw new MissingRouteParameterException(param.Name, r.RouteData.RoutePath);
}
foreach (var param in r.RouteParams)
{
if (param.Data != null)
{
if (param.Data.DefaultValue != null)
{
route.Defaults.Add(param.Name, param.Data.DefaultValue);
}
if (param.Data.Constraint != null)
{
route.Constraints.Add(param.Name, param.Data.Constraint);
}
}
}
Routes.Add(r.RouteData.Name ?? r.RouteData.RoutePath, route);
}
return Routes;
}
}
}
Getting the Routes into the RouteTable
Slapping route attributes onto your classes and methods is all well and good but it doesn’t mean anything unless we can get those routes into the RouteTable object easliy. Originally I had the code to add the routes looking something like
var routes = Assembly.GetCurrentExecutingAssembly().GetRoutes();
routes.ForEach(r => RouteTable.Add(r));
This, although pretty easy, wasn’t as readible as I wanted. So I added some extension methods to the RouteTable class:
RouteTable.Routes.IncludeRoutesFromAssembly();
I think both of these are much clearer than doing:
RouteTable.Routes.MapRoute("Root",
"",
new { controller = "Test", action = "GetItem", id = 1 });
RouteTable.Routes.MapRoute("Search",
"Search/{id}",
new { controller = "Test", action = "Search", id = 1 });
//.. SNIP ...
Using the RouteAttribute and RouteParamAttribute
In the controller “TestController” below there are three actions: Index, FindByText, and GetItem. Using the RouteAttribute and RouteParamAttribute makes it pretty clear that the routes for FindByText and GetItem are the same but use different RouteContraints.
So a request for /Test/Search/Hello will go to FindByText while /Test/Search/1 will go to GetItem. Also notice how GetItem has a default value of 2 for the id argument.
public class TestController : Controller
{
[Route(RoutePath = "Test")]
public ActionResult Index()
{
return View();
}
[Route(RoutePath = "Test/Search/{query}")]
public ActionResult FindByText(
[RouteParam(Constraint="[a-zA-Z]{1,}")]
string query)
{
return View();
}
[Route(RoutePath = "Test/Search/{id}")]
public virtual ActionResult GetItem(
[RouteParam(Constraint=@"\d{1,}", DefaultValue=2)]
int id)
{
return View();
}
}There is support for binding multiple routes to the same action; just add another Route attribute:
[Route("Products/Search/{id}")]
[Route("Products/{id}")]
public ActionResult GetProductById(int id)
{
return View();
}
Downsides or things I haven’t gotten to yet
Just some gotchas that I think people might raise issue with.
All of your controllers must inherit from the System.Web.Mvc.Controller class
This isn’t really a big deal because if you are using Asp.net MVC then you really should inherit from the Controller class, but for those of you using FubuMVC or another MVC framework this should be easy to change.
Attributes can be ugly
I know a few people out there are against attributes but I think that this is a more than acceptable use because it made the code much easier to understand.
Reflection can be slow
Honestly, when I first started working on this demo I was sort of turned off by the use of Reflection myself. After weighing the possible performance loss against the gains in both readability and maintenance I decided this was definitely worth it. I haven’t performance tested this code so, as always YMMV.
As always, if I screwed up or there is a better way to do this, please let me know in the comments.
Download the source code mentioned in this blog post.
asp.net · c# · code · MVC · Open Source
Long story short: I hate re-inventing the wheel. If there is a free service that does something I need I will try my hardest to get that service into whatever I am working on. I’m currently working on an Asp .Net MVC project that needs Avatars (you know, those funny little pictures next to peoples names on Twitter). Enter Gravatar.
Gravatar is an awesome service for anyone looking to add avatars to their apps. It’s free, incredibly simple to implement, and removes a lot of the hassle around getting avatar support into your web/windows app.
Adding Gravatar support to an application is pretty simple. Can you get a users email address? Can you MD5 said email address? Can you make an HTTP GET? BANG. You sir, or madam, can have Gravatars.
This week for the W.O.M.M. code sample I’d like to show how I integrated gravatar support into an Asp .Net MVC application.
How Gravatar Works In A Nutshell
Gravatar is a free service where you sign up and link images to one or more email addresses that you provide.
Once you link an image to an email address, any application that supports getting an image over the internet can show your Gravatar by making a request to a special URL. This URL is generated by combining an MD5 hash of your email address with some other parameters and the end result is a link to your Gravatar image.
IE: the link to my Gravatar on the right of this page is:
http://www.gravatar.com/avatar/15559d868ec27b8583f42116a6b96c14?s=140
So 15559d868ec27b8583f42116a6b96c14 is the hash of my email address – don’t worry it’s a one-way hash. The “s” parameter is the size of the image that I want, in this case 140 pixels.
That is pretty much it as far as how the system works, but if you want to read more, check out Gravatar’s implementation documentation.
The Goal
What I wanted was an HtmlHelper extension method that I could use in my view pages to create an IMG tag with the correct Gravatar URL. After looking at the documentation on Gravatars “How the URL is constructed” page, I decided my helper extension should support the following:
Avatar Size (the “s” parameter)
When making a Gravatar URL you can specify a specific size for the Gravatar image. The size can be anything from 1 to 512 pixels, but the default is 80.
Default Avatars (the “d” parameter)
If the email address you are using doesn’t have any Gravatars setup, Gravatar will generate one for you by default. You can choose from 3 predefined Gravatar types or you can include a URL to a custom avatar of your own. The predefined Gravatar types are Identicon, Wavatar, and Monsterid.
Rating (the “r” parameter)
This wasn’t a requirement for what I was working on, but you can designate the maximum “rating” of the avatars that Gravatar will generate. The accepted values are “g”, “pg”, “r”, and “x” and they are inclusive, so specifying “r” will allow “g” and “pg” rated Gravatars to be generated. Gravatars that are rated “x” will be returned as one of the predefined avatars above. The default rating is “g”.
The Code
Okay, so now I know what I need to support. Now it’s just a matter of getting the code to do this. Let’s take a look at the class file I used to get this done.
namespace System.Web.Mvc
{
using System;
using System.Web.Routing;
using System.Web.Security;
public enum GravatarDefaultTypes
{
Identicon,
Wavatar,
Monsterid,
Custom
}
public static class GravatarExtension
{
public static string Gravatar(
this HtmlHelper hh,
string emailAddress,
int size,
GravatarDefaultTypes defaultType,
string customImageUrl,
RouteValueDictionary htmlAttributes)
{
var tagBuilder = new TagBuilder("img");
string url = "http://www.gravatar.com/avatar/{0}?d={1}&s={2}";
// thanks to jon galloway for this one-liner!
// http://www.eggheadcafe.com/aspnet/how-to/141740/adding-gravatars-to-your.aspx
string hash = FormsAuthentication
.HashPasswordForStoringInConfigFile(emailAddress, "MD5");
string defImg = defaultType.ToString().ToLower();
if (defaultType == GravatarDefaultTypes.Custom)
{
defImg = System.Web
.HttpUtility
.UrlEncode(customImageUrl);
}
url = String.Format(
url,
hash.ToLower(),
defImg,
size.ToString());
tagBuilder.MergeAttributes(htmlAttributes);
tagBuilder.MergeAttribute("src", url);
return tagBuilder.ToString(TagRenderMode.Normal);
}
}
}
So you can see I’m not storing the hash of the email address, instead I am going to pass in the unaltered string. I didn’t want to have another piece of data to update when the user changed their email address so the Gravatar() method takes an email address and encodes it using a call to FormsAuthentication.HashPasswordForStoringInConfigFile(), which is awesome ( Thanks Jon, you rock!).
Also, I’m not sure if this is a no-no or what, but I did put the extension class under the System.Web.Mvc namespace. This was mainly a convenience (read: laziness) thing and can be easily changed.
Alright so we have some code now, let’s take a look at how it can be used in our views.
<%= Html.Gravatar(
Model.Email, // the email address
50, // size, in pixels of the avatar
GravatarDefaultTypes.Identicon,
null,
new RouteValueDictionary(new {
style = "vertical-align: middle;"
})
)%>
<%= Model.UserName %>
Let’s see how that looks.
Booyah, avatar support in 55 lines of code. As always, if I screwed up or there is a better way to do this, please let me know.
asp.net · c# · MVC · Open Source
Due to me being insanely sick this week I’m going to be changing up the format for the Works On My Machine weekly project post for this week.
Instead of presenting a project that I’ve worked on I’d like to highlight some .Net OSS projects / source code that I’ve been working with / looking at lately.
- The More Linq project – An extension library for LinqToObjects run by Jon Skeet.
- MusikCube – Awesome music player that uses SqlLite to allow “smart playlists” (eg. show me all songs that were added this week that have fewer than 4 stars and have been played less than 10 times).
- Moq – IMHO the best mocking framework for .net development.
- Scott Hanselman posted some code on his website a while back about how to Zip Compress your Session and Cache data in Asp.net.
Feel free to send me any code that you come across and I’ll feature it in a future post.
