Daily Learnings: 01/01/2011

How to get File Extension in PHP ?

Very Simple! This command should do that:

$ext = pathinfo($filename, PATHINFO_EXTENSION);

Another GoogleDoc API Issue

After getting past of one issue. Here is another error log I got:

com.google.gdata.util.ResourceNotFoundException: Not Found <HTML> <HEAD> <TITLE>Not Found</TITLE> </HEAD> <BODY BGCOLOR="#FFFFFF" TEXT="#000000"> <H1>Not Found</H1> <H2>Error 404</H2> </BODY> </HTML>

Solution is simple ! Replace URL mentioned in Google documentation.
Replace this: URL documentListFeedUrl = new URL("http://docs.google.com/feeds/documents/private/full");
To: URL documentListFeedUrl = new URL("http://docs.google.com/feeds/default/private/full");

You will get your document listing :)

Started Using GoogleAPIs ?

I have recently tried out google apis and found this dazzling problem after importing all the jars documented in GoogleAPI documentation:

Exception in thread "main" java.lang.NoClassDefFoundError: com/google/common/collect/Maps
at com.google.gdata.wireformats.AltRegistry.(AltRegistry.java:118)
at com.google.gdata.wireformats.AltRegistry.(AltRegistry.java:100)
at com.google.gdata.client.Service.(Service.java:555)
at TestDocumentList.main(TestDocumentList.java:14)
Caused by: java.lang.ClassNotFoundException: com.google.common.collect.Maps
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
... 4 more

Actually, in documentation they forgot about importing google-collect-1.0-rc1.jar. You can find this jar in gdata/bin/deps/google-collect-1.0-rc1.jar. Don't forget to add this in your build path.

How to make MySQL working on Mac OS X

Installing and configuring MySql in Mac was such a pain for me. I have installed and run MySql on Windows and Linux systems at least for 20 times by now, without any trouble. I assumed it will be quite simple in Mac as well. Actually, I hoped for easy installation because Apple products are considered user-friendly....but not developer friendly :(

Anyhow, I got it working now :)
1- Download binary from Mysql downloads
2- Copy /usr/local/mysql/support-files/my-medium.cnf to /etc/my.cnf
3- Start MySql using : /usr/local/mysql/support-files/mysql.server start
4- Stop MySql using : /usr/local/mysql/support-files/mysql.server stop
5- Check MySql Status: ps xa | grep "/usr/local/mysql/bin/[m]ysqld"

You may get some errors in bin dir path. You may want to fix paths in /usr/local/mysql/support-files/mysql.server (at least I did)

I have installed Workbench GUI for administration purpose. Good enough to give a try !

Installing mysql using Macports

sudo port install mysql5 +server

Using MySql Command Line

1- Show me MySql users: select * from mysql.user
2- Log in as user "root" (hit enter for blank password): mysql -u root -p

How to disable Mysql at startup in Mac OS X

1- Open hostconfig file in vi editor : vi /etc/hostconfig
2- Change "MYSQLCOM=-YES-" to "MYSQLCOM=-NO-"
3- Save and exit

Apache error log in Mac OSX

Its located at: tail -f /private/var/log/apache2/error_log

GIT: Squash (Comitting multiple files to gerrit under one review)

I am showing here how to push multiple files under one gerrit review.

Pre-requisites: You need commit-msg hook configured in your local repository.
1- scp -p -P :hooks/commit-msg .git/hooks/
2- curl http:/:port/tools/hooks/commit-msg

Steps:
1- Work and commit usually in your local copy
2- git rebase -i HEAD~6 (6 is the numbers of version you want to squash together)
3- pick base version and replace "squash" for "pick" for the commits you want to squash together. All squashed commits will go together with the "pick" one into gerrit review.
3- Modify changeId in rebase process when asked (make sure changeId should be same as that of already created review process)
4- push to gerrit

Git Stash

Stashing your changes: It saves your local changes on stash stack and revert your working copy to HEAD

git stash save

bash-3.2$ git stash save
Saved working directory and index state WIP on testing: fb1f22c This is test commit commit-amended
HEAD is now at fb1f22c This is test commit

Viewing your stashed changes:

git stash list

bash-3.2$ git stash list
stash@{0}: WIP on testing: fb1f22c This is test commit commit-amended
stash@{1}: WIP on testing: fb1f22c This is test commit commit-amended

Applying your stash :

git stash apply stash@{0}

OR
This applies latest stashed copy of your changes

git stash pop

Deleting Stash

Delete Particular Stash:

git stash drop stashId

bash-3.2$ git stash drop stash@{0}
Dropped stash@{0} (3b88e6278d1bb2bcf600ff9a5dde50116361a200)
Delete All Stashes:

git stash clear

Installing Hudson on Mac OS X (Snow Leopard)

This is a 5 step process:

Install hudson.war in your download directory : ~/Downloads
Create a hudson directory in your home folder : mkdir -p ~/hudson
Copy hudson.war from ~/Downloads/ to ~/hudson directory: cp ~/Downloads/hudson.war ~/hudson/hudson.war
Run hudson at port of your choice: java -jar ~/.hudson/hudson.war --httpPort=8082
Configure Hudson Jobs !

Creating Multi level directory in Linux

Linux doesn't create a directory at an unknown path. For example- If I want to create a directory firstLevel/secondLevel, firstLevel should already exists. Otherwise, give -p option with mkdir like this:

mkdir -p firstLevel/secondLevel

This will create firstLevel first, and then secondLevel under it.

Steps to create a Gerrit review

Git and Gerrit have been quite confusing together sometimes. Specially, in lack of good documentation. Doesn't seem like lot of people are using them efficiently.
In this post, I am trying to explain that how to create a review in gerrit and modifying a file under one review multiple times.

Pre-requisites: You need commit-msg hook configured in your local repository.
1- scp -p -P <gerritserver>:hooks/commit-msg .git/hooks/
2- curl http:/<gerritserver>:port/tools/hooks/commit-msg

Step-1. Change a file
Step-2. Commit this file using: git commit -a -m "commit message"
Step-3. Push change to gerrit to create a new review. git push gerrit HEAD:refs/for/branchname
Step-4. Amend a file for the next change: git commit --amend <filename>
Step-5. Iterate Step-3,5

Using ImageMagick to Crop an Image

I was looking into ImageMagick to understand its crop option. Since, I don't have very good understanding of image components and its terms, I couldn't make much sense out of it. But looks promising. Now, I am hunting for some friendly examples for crop feature. I was referring to this link to understand it: crop_gravity