Check XPath in Firefox with Firebug

There is easy way to check any XPath expression in Firefox if you have Firebug plugin. Just type:

$x('//a')

with your XPath expression and it will output list of matched elements, so you can click it and see on the page. Very handy to check Selenium XPath selectors.

Debugging grails in Netbeans

Grails plugin for Netbeans lacks some must have features like test launching from IDE and so on. Fortunately, Grails debugging is still super-simple with Netbeans. All you have to do is to run Grails from console with grails-debug instead of simply grails. For example, you want to debug test SeleniumTest.
Just type command in command console:

grails-debug test-app functional: SeleniumTest

Then go to Netbeans and select from menu Debug > Attach Debugger..., by default there is JPDA debugger, connector - SocketAttach, just enter your host and port (default is 5005, you can see yours in Grails console). Press OK. And it should connect to Grails process, so it will stop on breakpoints. Easy.
One thing to notice is that if you want to evaluate some expression in debug mode, you should use Java, but not Groovy, at least now.

Local git setup error

Recently I decided to check GIT. I am old fan of Tortoise tools and I decided to start with TortoiseGit. It is nice tool with familiar interface.

I am a little familiar with Mercurial and heard that they are quite similar in concepts. So I started by creating repository by command “Git create repository here”.
Then I created “Git Clone” of my repository in new folder. Then I started to play and created new files and commited changes. But then, when I tried to push my changes to master repository I got big ugly error:

git.exe push    "origin" master:master

remote: error: refusing to update checked out branch: refs/heads/master        
remote: error: By default, updating the current branch in a non-bare repository        
remote: error: is denied, because it will make the index and work tree inconsistent        
remote: error: with what you pushed, and will require 'git reset --hard' to match        
remote: error: the work tree to HEAD.        
remote: error:         
remote: error: You can set 'receive.denyCurrentBranch' configuration variable to        
remote: error: 'ignore' or 'warn' in the remote repository to allow pushing into        
remote: error: its current branch; however, this is not recommended unless you        
remote: error: arranged to update its work tree to match what you pushed in some        
remote: error: other way.        
remote: error:         
remote: error: To squelch this message and still keep the default behaviour, set        
remote: error: 'receive.denyCurrentBranch' configuration variable to 'refuse'.        
To C:\########
 ! [remote rejected] master -> master (branch is currently checked out)
error: failed to push some refs to 'C:\########'

This was quite confusing and error is not helping much. Also this scenario was working nicely with Mercurial, so I was really confused. But after some googling I found really nice article about git at http://cworth.org/hgbook-git/tour/, and it is explained nicely how to create repository that can be used with “push”. You just have to create it with

git --bare init --shared

It is really strange that there is no any option that can be set while creating repository and you still have to do it command line way. But issue was solved.

Wildcards in CLASSPATH

I am a little bit ashamed, but I didn't knew that since version 6, Java supports wildcards in classpath definitions. It is not that important nowadays when everyone is using build tools and IDEs, but still, it is nice that it exists. I guess for me it would be hugelly usefull some 10 years ago.

More information at http://java.sun.com/javase/6/docs/technotes/tools/windows/classpath.html

When Greasemonkey scripts run?

Recently I found one interesting thing about Greasemonkey. I was moving my scripts from JQuery to plain Javascript and changed $(document).ready() to window.onload() and my script stopped to work. After investigating a while I found that $(document).ready() is called also AFTER document is loaded and window onload obviously only when onload event is fired. This is interesting feature by itself, but I was surprised that Greasemoneky code is called only after document is loaded. Somehow I was not thinking about it this way with many many years of onload usage.

Anyway this is great, because my Greasemonkey scripts looks much cleaner without these unnecessary callbacks - just plain logic.

Spring Roo with GWT

I tried Spring Roo recently and there are my comments about it.

Spring Roo is a tool that automates application development and configuration. It is like Maven, but Maven automates project setup and development tasks, and Spring Roo automates application development and tools integration.

Good:

1) Great idea. No doubt it is really good idea to speed up setup and scaffolding of java application. As most of them use the same set of technologies (Maven, Hibernate, JPA, Spring, Struts, jQuery, Selenium, AspectJ, JUnit) and if you have to configure everything by your own it can easily take hours (I wonder if there is competition for fastest java project setup like: fastest Maven+Struts+Spring+JPA, fastest Ant+Spring MVC+Spring+JPA). There is defenitely no need to be so.

2) Fast. No need to do it manually.

3) No dependency. At one point, there were already prebuilt setups in form of application servers, but then you have lifetime dependency on application server. With Spring Roo there is no dependency - you can loose it any time. This is also great feature. In contrast, Grails is another great tool, but also creates dependency.

Improvements:

1) Configurable tools. It is already there at some point, but what I mean it is like to have ready setups for different tools. Like setup Spring+Struts+Hibernate+Ant+jQuery application, or another setup Spring+Maven+Spring MVC+Hibernate+GWT.

2) Aspects overuse. There is one funny approach to entity files: it creates one aj file for every use case for specific. Like there is one aj file for toString method, one aj for persistence operations, one aj for properties, one aj for setters and getters, one aj for @Configurable annotation. Total 5 files per entity. I have never worked with such approach, but it looks strange to me. It is good if it at least could be configured.

Conclusion:

It is great idea. I would be totally happy if there would be tool that can create ready setup with some example stubs where I just have to pick necessary tools, like:

create helloWorld --with spring, struts, hibernate, hypersonic, junit, jquery, selenium, jpa, rest, etc.

and it generates typical helloWorld with this info. I am happy. If it can create some entities - it is totally great.

Unfortunately, I don't think that Spring will support much of rival tools like Struts, Guice, JBoss, etc. And it will make it 99% less usefull for most users.

offsetHeight is 0 in Internet Explorer

Recently I had interesting issue while testing project in Internet Explorer. I have iframe burried under a long list of elements whose parent's height is updated by AJAX callback from iframe itself depending on iframe content height. In other browser everything works smoothly but in IE there is issue that document.body.offsetHeight is 0. I was digging issue and tried to debug it and finally noticed that when I stop with debug on the line that returns height - it showed correct number - and without debug still zero. I noticed that I had document.body opened on my watch list. After removing it - offsetHeight is again 0.

So there was some element in document.body that after being called, fixed offsetHeight to normal. And after small hack

    for (val in document.body) {
      var before = document.body.offsetHeight;
      document.body[val];
      if (before != document.body.offsetHeight) {
        alert(val);
      }
    }

I found that this magic element is filters and when it is called like

document.body.filters; 

it magically fixes documents offsetHeight.