How to Use Eclipse as a Ruby on Rails IDE

Update 11/23/2005: Months later, this is still apparently a popular topic, as it’s one of the most viewed posts here. Time has passed though, and there’s a better option: RadRails. It’s built on Eclipse, but includes Rails-specific tooling, which the configuration discussed below does not. It’s well worth your time to check out.

In this short tutorial, I'm going to walk you through setting up a code editing environment for Ruby on Rails using the Eclipse IDE.

About Eclipse
Eclipse isn't really an IDE in and of itself. It's more like a platform to build IDE's on. It was developed by IBM and then released as an open source project. The code is now owned by the Eclipse Foundation. IBM uses Eclipse as the foundation for all of their development tools, such as Rational Application Developer, their J2EE development tool. There are a variety of other companies and open source projects developing plugins as well as full-blown IDE's using Eclipse. See the Eclipse website for further information.

Note: Eclipse is a pig when it comes to memory and processor (mostly memory). If you don't have a 1.5ghz+ machine with 1gb of ram, you may find using it a little frustrating. I am using it on a machine with a 1.1ghz P4 and 512mb of ram, and it does OK, but it's not what I would call quick.

What we're going to do
What we are going to do here is install Eclipse (if you don't already have it), and then add two plugins to it. The first plugin will add support for editing Ruby code. The second will add support for HTML editing. Then we'll make some configuration changes to make everything work nicely, and that will be it.

NOTE:This is not a tutorial on Eclipse. I'm not planning on covering the ins and outs of Eclipse here, there are plenty of other sites that offer that kind of information. If you're interested in seeing a more in-depth tutorial on using Eclipse to edit Ruby/Rails code, drop me a line at \[larry AT\], and I'll consider developing one.

Installing Eclipse
The first thing you need to do is install Eclipse, if you don't have it already. Head over to, then download and install the latest version for your platform. Make sure to pick a stable release and not one of the milestone releases. Once you have it installed, start up Eclipse and go on to the next step.

Adding some plugins
Once you are in Eclipse go to Help ~~> Software Updates~~> Find and Install. This brings up a wizard-style dialog. On the first screen, make sure that "Search for new features to install" is selected, and click Next. The next screen let's you add/edit update sites where eclipse will look for additional functionality. We're going to add two sites here. First, click on the "New Remote Site" button. When the New Update Site dialog pops up, enter "Ruby" into the Name field, and in the URL field. Then click OK. You will now see your Ruby entry in the list of update sites. Click on the checkmark to the left of the entry to include it in the list of sites to search.

Now, click on the "New Remote Site" button again. Fill in the values as before, this time using "Web" as the Name, and as the URL. Click OK as before, and make sure you check the checkbox to the left of the Web entry. When you're all done, click Next.

The next screen takes you to the Search Results screen. This will give you a list of features you can install. We're interested in two here. Select the checkboxes for the latest version of "Ruby Development Tools" (currently 0.5), and "net.sourceforge.phpeclipse" (currently 1.1.4). Click Next. On the next screen you'll accept the licenses, and click Next again. On the final page, you'll choose the location to store the plugins. Select the default unless you have a reason to do otherwise. I had to add a new site to store mine in my home directory on Linux due to not having permissions to the default location. On a Windows machine you should be fine with the default. Now click Finish and confirm the dialogs that pop up. The download process may take a little time depending on your internet connection.

We need to let Eclipse know what to do with rhtml files. By default, Eclipse will treat it as a text file, which isn't what we want. In Eclipse, go to Window ~~> Preferences. In the tree on the left, navigate to Workbench~~> File Associations. Now click the Add button at the top of the dialog, next to the File Types list. Enter \*.rhtml in the dialog that appears and click OK. Now select our new type in the File Types list and then click the Add button at the bottom of the screen next to the "Associated Editors" list. Choose "HTML Editor" from the list that appears, and click OK. Now close the Preferences screen.

Almost Done
Now that we have everything installed, let's try it out. In Eclipse, select File ~~> New~~> Ruby Project. Enter a name into the dialog that appears and click OK. You should now see your project in the Navigator window on the left hand side of the screen. Now right click on that project name and choose "Import". I'm going to import a copy of Typo, the excellent blog software that runs this site. I happen to have this on my drive, if you don't have a rails project, either create one real quick or download something like Typo. When the Import dialog comes up, choose "File System" and click Next. Choose the directory your source code is sitting in. and then select it in the checkbox on the left like this: <img src="" align="Middle" width="500" height="500" alt="Import screen" / >
Now click Finish. Once the source is imported, you should see be able to navigate through the project tree in the Navigator window. If you click on ruby and rhtml files, you will see that they are opened in their proper editors.

That's it. You now have an Eclipse based environment for developing Rails code in. Here are a couple of screenshots to demonstrate what it looks like:

Editing an ERB File

Editing Ruby code

What’s Missing
So what’s missing from this? Well, a couple of things:

  • Eclipse doesn’t really understand ERB files. It would be great if the Ruby plugin understood them, as it would make the syntax highlighting much better. It would also allow for code completion, etc.
  • No documentation. A real IDE needs to have the Rails documentation embedded and searchable
  • WEBRick integration. It would be nice to be able to stop/start WEBRick from within the IDE.
Perhaps someone will tackle this project, as it seems there’s a good foundation already.

If you have questions or comments, I'd love to hear them. Leave me a comment, or email me at \[larry AT\]