Adding custom CSS to your Joomla site

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Written by Bogdan Mustiata

Created: 23 May 2013

Whenever you want to add a custom style to your's site CSS, I generally see the general "solution" to add the CSS to the template itself, eventually add some extra custom PHP inside your template from the templates folder. I dislike this solution, because then you need to remember that your template is actually tainted, and you can't just install the template and your CSS, you again need to fiddle with its internals.

Don't you just want a simple javascript to add custom CSS to your joomla site, without changing the template source, or dig to its settings?

Thus I preffer to add a module that will add some JavaScript (tested on IE7+, and all normal browsers). I also get for free fine grained control (not that's terribly useful) on where I want my custom CSS, and where not, since now it's just a module I can assign:

<script type="text/javascript">
(function() {
  
addCustomCss("my-custom.css");
 
function addCustomCss(name) {
    var css = document.createElement("link");
  
    css.setAttribute("rel", "stylesheet");
    css.setAttribute("type", "text/css");
    css.setAttribute("href", name);
  
    var html = document.body.parentNode;
    
    for (var i = 0; i < html.childNodes.length; i++) {
        if (html.childNodes[i].tagName == "HEAD") {
            html.childNodes[i].appendChild(css);
            break;
        }
    }
}
})();
</script>

Obviously it can be seen that I can add multiple custom CSSes, but generally I preffer only one. Since the node is appended to the head later that the head element that was outputted by Joomla, I also get my custom CSS last, which helps when it comes to CSS rules priorities, since the last rule wins for the same selector precision.

I hope it helps, and have fun designing your Joomla site.

GCJ write once, run anywhere at its finest

Details

Written by Bogdan Mustiata

Created: 22 May 2013

I remember once when we needed to deploy an application to a customer on two nodes using its RedHat Enterprise Linux, using JBoss 5.

Our prerequisites:

• Java 1.6
• JBoss 5

Because Java - compile once, run anywhere, right?

Wrong!

The customer comes back at us telling that our application deploys fine on one node, doesn't start on the other node - some really random runtime error deep inside JBoss.

"What the hell!" moment.

Obviously an environment difference, but which one?

Ok, can we get SSH access to investigate?

No.

Ok, we start ping-pong-ing emails with commands to give on the command line. Let's get the environment:

cat /etc/*release*

Same RHEL version.

JBoss?

Same exact version.

java -version

Working node: OpenJDK. Failing node: GCJ.

I'm baffled. Does the GCJ project still exists? Is anyone else beside Stallman still using it? Why is it installed?

I check their website thriving with news activity:

September 22, 2009
GCJ support on Windows (Cygwin and MinGW) targets has been enhanced with a number of bugfixes, and the option to build libgcj in DLL form for dynamic runtime linking.

Well, isn't that swell? Three years of nothing. Amazing.

I contact their admins and tell them to switch the failing node to OpenJDK.

What's wrong with this Java? they ask. Because it's in the repository, as java-gcj-compat.

A single tear rolls down my face, while I start typing a document explaining why GCJ is not really Java-Java, and how to upgrade it.

It was a bad day overall that day.

Creating a SHA1 hashing function for PostgreSQL 8.3 and Ubuntu 8.04

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Written by Bogdan Mustiata

Created: 15 May 2013

I think everyone needs from time to time this hashing method when it gets to work with user databases, for maintenance purposes.

As one who migrated from mysql to postgres - (actually I'm still dual using them) I was surprised to see this very useful function doesn't exist.

Don't worry, it's easy to add it.

On the terminal we first need to add the cryptographic libraries for postgres. The easiest way is to add the postgresql contrib, that contains a lot of goodies, and, of course, our crypto libraries. Also it is in the repository already.

$ sudo apt-get install postgresql-contrib-8.3

The next step would be exporting the cryptographic methods (except sha1 unfortunatelly) into the template from where each newly created database is derived:

$ sudo -u postgres psql template1 < /usr/share/postgresql/8.3/contrib/pgcrypto.sql

(in case you already have existing databases where you would need these functions, just change template1 to the corresponding database name, e.g.:

$ sudo -u postgres psql proddb < /usr/share/postgresql/8.3/contrib/pgcrypto.sql

)

Now we need to create our sha1 method (I've used the pgadmin3 tool in order to do that, but you can still use the psql approach for that).

As you can see the actual work is done by the more generic "DIGEST" method - which unfortunatelly returns a bytea, and converted to a string by the "ENCODE" method.

CREATE OR REPLACE FUNCTION sha1(bytea)
RETURNS character varying AS
$BODY$
BEGIN
RETURN ENCODE(DIGEST($1, 'sha1'), 'hex');
END;
$BODY$
LANGUAGE 'plpgsql'

If you want this method to be in every new table from now on, you could put it in some file (let's say sha1.sql) and run it against the template1.

$ sudo -u postgres psql template1 < ~/sha1.sql

After that, a simple

select sha1('test')

should return as expected:

a94a8fe5ccb19ba61c4c0873d391e987982fbbd3

Hoping it helps, I'll end here.

Struts2 Best Practices

Details

Written by Bogdan Mustiata

Created: 15 May 2013

After reading Struts 2 in Action (a definite read for people who have no experience at all using struts 2), and after finishing a project and actually delivering it to the customer, and in the middle of the second one, I've decided to write down the best practices that I follow.

The reason why i'm writing this is that I couldn't find real case examples of good patterns to follow in developing a struts2 application, even the best practices from that book are quite slim, and I'm not going to reiterate them here.

Tooling

• Buy IntelliJ Idea. I have no words to describe how much more advanced is this compared to eclipse. Jump to definitions of actions, jump to implementing classes, you can pick what action you want to go to from a class (if multiple actions are mapped to the same class), etc. Simply outstanding.
• Buy JRebel if you have I18N in your application. Although they brag to have struts2 support I couldn't make it work (even if conforming to their website should be "brainless" to do it). What it does well though is reloading of classes (like adding methods and co.) and bundle reloading.

Programming Style

• Don't write any code until you fully understand the ActionContext and the ValueStack, and how the property resolving takes place. Otherwise all the iterators and push constructs in the JSP will simply look like voodoo (I am talking from experience here).

• Write tests for your actions. It does seem a bit hard, but it is actually quite simple. Just add this dependency in your maven2 pom.xml file, and just create tests:
  
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  <dependency>
    <groupId>org.apache.struts</groupId>
    <artifactId>struts2-junit-plugin</artifactId>
    <version>2.1.8.1</version>
  </dependency>

• Don't create actions with multiple methods. "execute" and the operation you want to execute (e.g. "createUser") should be enough. Execute would be used for rendering a jsp/ftl/vtl template, and the action will be used to actually do your business requirement.

• All your validations, try to express them via annotations on the business method (@Validations), and if you can't since they're to complex, and expressions won't cut it, simply implement the validate() action. Never put validations in the model (if you're using ModelDriven actions).
  The reason is that you always have to check two files in order to see if the business method will be called.
  Another thing to keep in mind is if you use annotations AND multiple methods, struts 2 for some reasons collects all the annotations from all the methods and applies them against the current method being called. (as of 2.1.8.1)

• Use only one I18N package.properties file for the whole project. If the project gets big it's hard to track which key is where and you'll end up with lots of duplicate keys, and the fear of deleting the keys since you don't know who uses them will be there constantly; unless you're doing some funky searches against the package name in the java sources, and in the struts.xml config files.
  
  Not fun at all.

• Preffer interceptors over servlet filters. The only reason why you would want servlet filters is to intercept resources that are not actions. Otherwise the access to the ActionContext is invaluable. Both of them are fairly lightweight so I see no reason in having things that do the same thing in two places (web.xml and struts.xml).

• Create interceptors to inject services for you (like EJBs, or whatever counterparts are in spring). Your methods in the action should become simple wrappers over the actual business services. Also it becomes trivial to test, since the tests will also simply inject mocks of the actual services.
  Don't be afraid to create custom interceptors for whatever you need them. They are extremely lightweight

A "full" action implementation would be along these lines, so it is imediatelly clear what it does, what validations does it require, and is trivial to test:

public class RegisterUserAction extends ActionSupport {
    // ...
    private String username; // + getter/setter
    @EJB
    private UserService userService; // no getter/setter, set by interceptor
    
    public void validate() {
        // custom complex validations
    }
    
    @Validations(
        // ... most of the time validate() is not needed.
    )
    public String registerUser() {
        try {
            userService.registerUser(username);
        } catch (Exception e) {
            LOG.error(e.getMessage(), e);
            addFieldError("some_field", getText("some_specific_error_key");
            return INPUT;
        }
        return SUCCESS;
    }
    
    // execute is mapped as excluded in struts.xml for validations
    public String execute() {
        return SUCCESS;
    }
    // ...
}                          

That would be it. As usual, I'm extremely interested in your feedback.

Have fun programming with struts 2.