Praj's Blog

Select Users from Alfresco Database

Mon, 20 May 2013 18:30:00 +1000

The following SQL (designed for MySQL as it uses group_concat) pulls out a list of users from the Alfresco database by searching for the appropriate nodes in the Alfresco node table and pulling user node properties including username, firstName, lastName and email address.

select
    node_id,
    group_concat(string_value)
from (
	select
		node_id,
		qname_id,
		(select local_name from alf_qname where id = qname_id) as qname_type,
		string_value
	from alf_node_properties
	where node_id in (
		select id from alf_node 
		where type_qname_id = (
			select id from alf_qname where local_name = 'person'
		)
		and qname_id in (
			select id
			from  alf_qname 
			where local_name in (
				'username',
				'firstName',
				'lastName',
				'email'		
			)
		)
	)
) alf_users
group by node_id;

MySQL group_concat()

Sat, 18 May 2013 20:33:00 +1000

The group_concat() function in MySQL is really nifty. It concatenates all rows that match your group by statement into a single, comma separated string. Essentially, it transposes rows to columns.

Take this example. Say you have a table that stores a set of locations by country, state and city.

You could then write SQL as follows:

select country, state, group_concat(city) as cities from locations group by country, state

What this is saying is bring back 3 columns, country, state, and for each combination of country and state, a list of all of the cities in that country and state as the third column (called cities).

This is actually a phenomenally handy thing to be able to do, and something that is much harder to do in any other DBMS.

Git undo modifications

Thu, 16 May 2013 08:23:00 +1000

Much like you can get a list of deleted files, you can also get a list of modifications and then check them all out (undo) in one command using the following:

git checkout $(git ls-files -m)

This is effectively an “undo” of all modifications in the given branch (but it doesn’t impact added or deleted files).

Access Last Command Line Result

Tue, 14 May 2013 10:36:00 +1000

A nifty command to access the last result is $(!!).

For example you can do something like this:

$ find . -type f -name example.txt* ./a/folder/example.txt

$ vim $(!!)

As I only had one result from the find, I can that result and call vim on that file.

Alfresco Logs when using Alfresco Service

Fri, 10 May 2013 15:31:00 +1000

One very handy feature for Alfresco system administration is the alfresco service that is automatically installed on Linux environments. However, there is a catch when using this service, your various logs (e.g. alfresco.log, share.log, solr.log) can end up in the very root of your file system.

One partial workaround is to modify the various log4j configuration files and hardcode them to a specified location. However, there is a better way: edit the alfresco service.

By convention, I like logs to go somewhere sensible like /opt/alfresco/4.1.4/logs (or appropriate based on your Alfresco version). This folder doesn’t exist out of the box so you will need to create it. If choose another location, be sure to adjust the steps in this article accordingly.

Modify your service (e.g. /etc/init.d/alfresco — this depends on your Linux distribution) as follows:

Step 1:

First stop alfresco if it is currently running.

At the top of this script after RETVAL=0 add the following line (and adjust to match your installation path):

ALF_HOME=/opt/alfresco/4.1.4

Step 2:

Change the start() command to go to your logs folder (make sure it exists) and then start the alfresco.sh script (which is one level above the logs folder). You could also use $ALF_HOME/alfresco.sh as a full path. Obviously adjust these lines to suit.

cd $ALF_HOME/logs
../alfresco.sh start “$2”

Step 3:

In the same way as start(), change stop() to do a similar thing:

cd $ALF_HOME/logs
../alfresco.sh stop “$2”

Step 4:

Near the end of the script there inside the case … esac statement also change the script as follows:

cd $ALF_HOME/logs
../alfresco.sh “$@”

Step 5:

Clean up / move your old log files around as appropriate and then start alfresco. You should find all log files are now in the logs folder, without having to modify any of the delivered log4j configuration files.

Git remove multiple deleted files

Thu, 25 Apr 2013 06:46:00 +1000

Sometimes when you are committing changes in git you’ll find that a number of files have been deleted.

You could manually set these files to delete by individually issuing the command:

$ git rm filename

However, there is a shortcut. If you issue the command:

$ git ls-files --deleted

It will return a list of all files that are flagged as deleted.

You can then simply pass that list to git rm, using a combined syntax like this:

$ git rm $(git ls-files --deleted)

(Just don’t forget the —deleted parameter!).

Disallowed Key Characters Error

Sat, 06 Apr 2013 11:18:38 +1000

I loaded a CodeIgniter site today and received a blank page with just the message “Disallowed Key Characters”.

There are myriad of scenarios that can cause this to occur. In my particular example, it occurred due to the fact that my application/config.php file had the following set:

$config['cookie_prefix'] = "<CHANGEME>_";

I had put that in as a placeholder, but the “<” and “>” symbols are not allowed in this particular config value and throw this error. There are other symbols that will also cause this, so something to watch out for.

After you change this, remember to clear your browser cookies too.

"If you follow the herd, you’ll end up stepping in a lot of shit!"

Wed, 03 Apr 2013 05:30:34 +1000

“If you follow the herd, you’ll end up stepping in a lot of shit!”

jQuery Reveal Tips

Fri, 22 Mar 2013 05:30:52 +1000

I’ve mentioned the jQuery reveal modal plugin before, and I think there are two really good tips about how to use it that aren’t clear on their site which might come in handy to people who use it.

To trigger jQuery reveal on page load for the relevant reveal element (e.g a div):

$(document).ready(function() {
    $('div#your-reveal-div').reveal();
}

Similarly to close on clicking of the “close” (X) button:

$('a.close-reveal-modal').on("click", function(e) {
   $('div#your-reveal-div').trigger('reveal-close'); 
});

Check for root access in a bash script

Thu, 21 Mar 2013 05:30:00 +1000

Just something handy to put in your script if you need to check for root access:

# Do we have root access? if [[ $(/usr/bin/id -u) -ne 0 ]]; then echo ""Sorry, this script needs to run with root or sudo access" exit fi

Dev-Admins

Tue, 19 Mar 2013 05:30:00 +1000

With the way things are going in the software and IT industry, I think there’s a strong case for a new role:

"Dev-Admins"

These are developers who also contribute to the design, implementation and management of systems that not only assist with development (e.g. revision control, development environments, integrated testing), but also contribute to system administration related duties for production systems such as web applications and database management.

Why have such a role? Well, in a lot of cases, it is the developer and not so much the system administrator that has the knowledge and insight about any customised systems deployed. They are often uniquely placed to provide guidance on areas such as system configuration and performance tuning.

I know in smaller companies, developer’s naturally assume such roles (due to necessity). Perhaps, in bigger companies, such roles need to be formally identified?

Alfresco Javascript Debugger

Thu, 14 Mar 2013 20:09:00 +1000

When developing on Alfresco, you’ll want to use the Alfresco Javascript Debugger to debug server-side Javascript.

On a local install this is available through URLs like this:

http://localhost:8080/alfresco/s/api/javascript/debugger
http://localhost:8080/share/page/api/javascript/debugger

However, on certain installations, for example the Mac OSX, when you go to turn on the Javascript debugger you’ll get the following error:

The Web Script /share/page/api/javascript/debugger has responded with a status of 500 - Internal Error.

In the relevant log, you’ll also see a message along these lines:

Caused by java.awt.HeadlessException at java.awt.GraphicsEnvironment.checkHeadless(GraphicsEnvironment.java:159) ...

This is actually caused by a setting passed to Java in the tomcat ctl.sh script which starts Alfresco and sets java.awt.headless to true, disabling graphical interfaces like the Javascript Debugger.

So to get the Javascript Debugger working, open up tomcat/scripts/ctl.sh and remove -Djava.awt.headless=true in export JAVA_OPTS= in the start_tomcat() and daemon_tomat() functions.

Alfresco could not resolve view error

Sat, 09 Mar 2013 05:30:35 +1000

In Alfresco Share (share.log), I kept getting this error and couldn’t figure out what was causing it:

ERROR [org.alfresco.web.site] javax.servlet.ServletException: Could not resolve view with name 'user/guest/dashboard' in servlet with name 'Spring Surf Dispatcher Servlet'

After a lot of fruitless google searching and trial and error, I finally tracked it down to items missing share-config-custom.xml, so if you get something similar, review your share-config-custom.xml in detail.

aText

Fri, 08 Mar 2013 05:30:29 +1000

I just switched over to using aText as my text-expansion software on the Mac (have previously tried TextExpander and DashExpander).

It does everything I need, imports snippets from Text Expander, and costs a fraction of the price of TextExpander. So I’m thoroughly impressed.

One caveat which I’ve found is that if multi-line snippets aren’t expanding properly for you e.g.

Example Snippet

With

Mulitple Lines

Expands to:

Example Snippet With Multiple Lines

Try enabling “Always use Clipboard to insert snippets” in the preferences. That fixed up this problem for me in Sublime Text and Netbeans.

Thanks to Tran for creating such a great product and letting me know about this fix too.

Mastering your time

Thu, 07 Mar 2013 05:30:28 +1000

Came across this article the other day, a fun and important reminder of doing things that are important (taking control of your time) rather than those that are urgent (letting others control your time):

http://abetterlife.quora.com/How-to-master-your-time-1

It’s harder to do than you would think, and you can sabotage yourself in subtle ways e.g.

Do you catch yourself waiting on things to pop up in your inbox/im/social network/etc to guide what you are going to do next?
Do you find your days are full of “fire-fighting”? Moving from one urgent task to the next, without considering what’s actually important?
When you have a chunk of time free, do you have a clear plan about what to do next?
Can you justify why you are doing the thing you are currently doing? How does it match up to your goals and what you want to achieve?
Have you done something, anything to contribute towards achieving your most important goal today?

The other great reminder from this is that there is limitless number of stormtroopers - urgent tasks that will come your way. Don’t be fooled into thinking you can just get one more thing done before starting what’s important …

Removing a stubborn Firefox Extension

Wed, 06 Mar 2013 05:30:00 +1000

If you are having trouble removing a stubborn Firefox Extension and don’t see it in your Firefox profile (see here), then have a look in the separate “Mozilla” folder. E.g. ~/Library/Application Support/Mozilla/Extensions.

Some extensions go here and you won’t be able to remove them from Addons until you delete them manually from this folder.

bunzip2 gives input file has 1 other link

Wed, 27 Feb 2013 05:30:47 +1000

If you get this when you try bunzip2 filename.ext.bz2, then try bzcat using bzcat filename.ext.bz2 > filename.ext.

Check the Status of Google Servcies

Tue, 26 Feb 2013 05:30:34 +1000

If you think there might be a Google service issue, be sure to check out their AppStatus page:

http://www.google.com/appsstatus

PHP Syntax Check Multiple PHP files

Sun, 24 Feb 2013 05:30:51 +1000

Found this pretty cool link to how to syntax check multiple PHP files by passing the results of a find to php -l.

I’ve extended this and grepped out any files that pass syntax checking so you are just left with the errors. Here’s the full command in all its glory:

$ find . -name "*.php" -print0 | xargs -0 -n1 -P8 php -l | grep -v "No syntax errors detected"

Force PHP errors to display

Sat, 23 Feb 2013 05:30:28 +1000

If you are really stuck and not getting any useful information regarding PHP errors in your log files, then you can the following to the relevant PHP file and it will display those errors on screen:

error_reporting(E_ALL);

ini_set("display_errors", 1);

Very handy when you are really stuck!