Software Development Problems

Web2py - remove the "delete" check box

2012-01-21T00:12:00.000-08:00

In web2py, the form displayed to update form containing an input file is like this :
name + input text + "browse" button + [file + delete check box]

Problem : how can I remove this "delete" check box ? Because the image is required. If I check the value is not null, it returns false, because the value is empty.

Solution : it's really easy. In your file db.py just add: requires=IS_NOT_EMPTY


Field('data', 'upload',requires=IS_NOT_EMPTY())

And that's it !

web2py - add a foreign key to aut_user

2011-11-08T16:46:00.000-08:00

I'm still doing my project in web2py, and I wanted to add a foreign key in my auth_user table.

Problem: in the file models/db.py, you first declare the tables auth_* and then the other tables. So if you add your foreign key you'll get an error because the "foreign table" doesn't exist yet.
Example :



auth = Auth(db)
auth.settings.extra_fields['auth_user'] = [Field('myFK', db.foreignTable)]
auth.define_tables() 

db.define_table('foreignTable',Field('name', length=45) )

So I tried to define my foreignTable before settings.extra_fields, but it didn't work either...

Solution :
The only solution I could find was the following :


auth = Auth(db)
auth.settings.extra_fields['auth_user'] = [Field('myFK', integer)]
auth.define_tables() 

db.define_table('foreignTable', Field('name', length=45) )

db.auth_user.myFK.requires = IS_IN_DB(db, 'foreignTable.id', '%(name)s', zero=T('choose one'))

At first I declare my column as an integer, and after I define my foreignTable. Then I link myFK to my foreignTable.

And that's it!

How to install web2py on a shared host

2011-10-13T20:13:00.000-07:00

I'm working on a project with a friend using web2py

Free open source full-stack framework for rapid development of fast, scalable, secure and portable database-driven web-based applications. Written and programmable in Python.

Official website

Now that we are ready to upload our website, we were looking for good shared host. It was not easy to find a good one. Finally we choose Site5 because it supports Python and the server is in Montreal.

Problem:

how to install web2py on a shared host ?

Solution:
I could find this website : web2py on shared hosting.
I followed the instructions from "Installing web2py".

When you do this, here is the url to see your app :
http://www.mydomain.com/web2py/mySuperApp/default/index

But what we wanted was something like that :
http://www.mydomain.com

So here are the modifications :
- move all the web2py files directly to "public_html".
Before : $HOME/public_html/web2py/web2py.py
After : $HOME/public_html/web2py.py
(it's just an example with web2py.py file, but you should move all the files!)

- edit $HOME/public_html/routes.py, your file should just contains :

routers = dict(
    BASE = dict(
  default_application='mySuperApp',
  domains={'mydomain.com' : 'mySuperApp'},
    ),
)

*routers is a new feature of web2py. This parameter-based system first appeared in web2py version 1.92.1.
If you want to know which version of web2py you're using, just open the file $HOME/public_html/VERSION

And that's it ! Now you can access your application simply by using : www.mydomain.com !

Adding Syntax Highlighting to Blogger

2011-07-28T19:33:00.000-07:00

Problem
How to add syntax highlighting to Blogger ?

Solution
I couldn't find a better way than this website :
http://heisencoder.net/2009/01/adding-syntax-highlighting-to-blogger.html
That helped me a lot !

Android Mini Collectibles

2011-07-28T18:56:00.000-07:00

*2011-08-09 The figures that I'm talking about are fake! Please read the comments

Today I'm not going to talk about software problem.
I want to talk about the Android Mini figures. I bought some and I'm not totally satisfied by the finishing.
Of course if you look at the official website (Dyzplastic) it looks very nice. And I think 80% of the time it is nice.
But here are some "bugs" that I could see.

1) Head
As you can see on the picture, there are 2 Reactor, but the one on the left has some strange stain on his head.

2) Paint
This looks like the painting was not done correctly

3) Dirty
This other Albino looks dirty (not as white as the other one)

4) Glue
The box opened by itself from the bottom. Cheap quality glue...

Well, the price of these figures is cheap but I was expecting something better from Google.

Yii - Right join

2011-06-11T07:20:00.000-07:00

I wanted to learn something new so I decided to create a website using the framework Yii (more info). It's written in PHP and I think it's pretty cool.

Yii comes with rich features: MVC, DAO/ActiveRecord, I18N/L10N, caching, authentication and role-based access control, scaffolding, testing, etc. It can reduce your development time significantly.

But I'm having a problem that I can't solve right now.

Problem

I have 2 tables :
- tbl_prono (id, game_id, ...) : there are 2 rows of data
- tbl_game (id, date, team_id,...) : there are 3 rows of data

In my model Prono I did the following relation:

return array(
'game'=>array(self::BELONGS_TO, 'Game', 'game_id'),
);

I created the following dataprovider in an action (PronoController):

$dataProvider=new CActiveDataProvider('Prono', array(
'criteria'=>array(
    'with'=>array('game'=>array('joinType'=>'RIGHT JOIN')),  
    // please note the RIGHT JOIN
)));

$this->render('pronos',array('dataProvider'=>$dataProvider,));

It generates a correct sql querry. But it returns 2 rows instead of 3 !
It should return 3 rows because I'm doing a "right join" and tbl_game has 3 rows.

So, in my CgridView, I can see only 2 rows...

I couldn't find a solution to display 3 rows....

ORA-01940 cannot drop user

2011-04-13T12:43:00.000-07:00

Problem:
Oracle 10g, I want to drop a user using this command :
drop user alex cascade;

But I have this error:
ORA-01940: cannot drop a user that is currently logged in

Solution :
I checked on google and find this excellent Website : http://www.dba-oracle.com/t_ora_01940_cannot_drop_user.htm
It said that you should do this :

select s.sid, s.serial#, s.status, p.spid
from v$session s, v$process p
where s.username = 'myuser'
and p.addr (+) = s.paddr;

alter system kill session 'sid,serial#';

That's correct but your username should be in uppercase!
For example :

...
where s.username = 'ALEX'
...

And that's it !

You can do a quick test :


select username from v$session;
select * from v$session where username = 'alex';
select * from v$session where username = 'ALEX';

path oracle 10g

2011-04-13T06:27:00.000-07:00

Problem:
You can't execute commands such as "imp", "exp", "impdp" or "expdp" even though the path is setted in the environment variable.

Solution:
In my case, there was a mistake. When I installed Oracle 10g, the path was automatically set to :
PATH=C:\oraclexe\app\oracle\product\10.2.0\server\bin;C:\Windows\system32...

But in reality it should be "BIN" (uppercase)!
PATH=C:\oraclexe\app\oracle\product\10.2.0\server\BIN;C:\Windows\system32...

After modifying the path, I could execute the command "impdp" anywhere from the command line.

SQLiteDatabase created and never closed

2011-02-19T12:13:00.000-08:00

Problem
When I'm using my application and I can see this error in the LogCat tab :


02-17 17:20:38.556: ERROR/Database(434): Leak found
02-17 17:20:38.556: ERROR/Database(434): java.lang.IllegalStateException: /data/data/databases/xx.db SQLiteDatabase created and never closed

Solution
Well, at first I thought it was because of my cursors. So I decided to check every cursor and close them all after having done with them.
But I still got the same problem.

So in fact, it's just that for every activity (onCreate) I was opening a connection to the database, but I never closed it.
So the solution was to close the connection in each activity:


@Override
protected void onStop() {
 dbService.closeConnection();
 super.onStop();
}

And that's it !

Android Insufficient storage

2011-02-12T16:24:00.001-08:00

Problem
I was debugging my application using an android virtual device in Eclipse.
When I run the application I could see this error in the console:

[2011-02-12 19:22:25 - shiro] Installation error: INSTALL_FAILED_INSUFFICIENT_STORAGE
[2011-02-12 19:22:25 - shiro] Please check logcat output for more details.
[2011-02-12 19:22:25 - shiro] Launch canceled!

The size of my app is around 22Mo (there are a lot of pictures).

Solution
The first time I configured the android virtual device, I put only 2 or 3Mo for "SD Card size".
So I had no choice to create a new virtual device and put something like 30Mo.
I ran my app for the first time. No problem. Then I wanted to run it again, and I got the same problem. I guess I could set the size of SD card to 100Mo, or in the virtual device, you can go to the menu > settings > manage applications. Then choose the application and uninstall it. Then you can run your app again in debug mode from Eclipse.

And that's it!

Android: 2 view elements side by side

2010-09-06T09:01:00.000-07:00

In my Android application, I wanted to display 2 spinners, side by side (50% of the width each).
I didn't want to use width = "100px" for example. I wanted to be relative as much as possible.
So here is what I did:


      android:layout_alignParentBottom="true" android:layout_width="fill_parent">
        android:layout_height="wrap_content" android:weightSum="100">  
   
      android:id="@+id/btnBack"
   android:layout_height="wrap_content"
   android:text="@string/back"
   style="?button"
   android:layout_weight="50">
    
   
      android:id="@+id/btnMap"
   android:layout_height="wrap_content"
   android:text="@string/map"
   style="?button"
   android:layout_weight="50">

***WARNING*** XML tags are case sensitive. In my example above, I don't know why it's display in lower case... Please use TableLayout, TableRow and Button!

I created a tableLayout with 1 tablerow. In each tablerow I added 2 buttons.
I set the attribute weightsum="100" to the row. And for each element of the row,I set layout_weight="50".
And that's it!

ruby - windows7 - mysql

2010-06-10T10:08:00.000-07:00

So I tried to install Ruby on Rails on my windows 7, but it was strange...
First, I followed this tutorial -> http://rubyonrails.org/download

1) I installed Ruby on my C:\
2) I installed Gem on my C:\
3) I did gem install rails, but it says it needed other gem (activesupport, rack....)
Strange... So I downloaded each missing gem and did gem install rack-1.0.0.gem
Then I could install rails!
4) I installed mySQL and NetBeans.

but impossible to create table (db:migrate), and suddenly I have a blue screen...

In fact there was 2 problems.
1) The drive C:\ is kind of protected for writing (Vista & 7). I uninstalled Ruby and installed it on D:\.
After that, when I did gem install rails, it worked like a charm.

2) I couldn't create tables because mySQL5.1 doesn't like Ruby very well. So you should download a latest library. For more information, please see -> http://forums.aptana.com/viewtopic.php?f=20&t=7563&p=27407&hilit=libmysql.dll#p27407

And that's it!

VB .net avec win7 x64

2010-04-16T09:18:00.000-07:00

So here is one thing that may help other people.
I have Win7 x64 and a VB application using Microsoft Access DB. My version of Office is 2007 32 bits.
The VB application is old, and I have to make it works on VS2008. Before it used OLEDB4.0. When I started the program I had this error: provider is not registered on locale machine.

After searching on the Web, I found out that I needed to install new driver (or provider) from Microsoft Website: 2010 Office System Driver Beta: Data Connectivity Components.

And here is what I understood:

download 14.0.4536.1000_AccessDatabaseEngine_none_ship_x86_en-us_exe\AccessDatabaseEngine.exe if your Office is 32bits.
in the properties of your VB application, go to advanced compile options and choose CPU target: x86
in the string connection, use: gDB.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=""MDITMain.mdb"";Persist Security Info=False". Do not use "14.0". This is a bug, you can find more information on google

If you want to test your DB connection, check here: "UDL Test" on a 64 bit machine
Here is what was inside my UDL file:
[oledb]
; Everything after this line is an OLE DB initstring
Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\xxx\Documents\Visual Studio 2008\Projects\WindowsApplication1\WindowsApplication1\DBMain.mdb;Persist Security Info=False

That's it for now

Android join tables

2010-03-25T19:44:00.000-07:00

In my application, I have many tables and for a reason, I had to do a query using "join".
I'll not explain how to access a database, but just so you know, check on Google for
object SQLiteDatabase.

So I was checking at the method query , here is the information:


public Cursor   query  (String  table, String[]  columns, String  selection, String[]  selectionArgs, String  groupBy, String  having, String  orderBy)

Parameters
table :The table name to compile the query against.

For example:


Cursor cursor = myDataBase.query(
    "myTableA" ,
    new String[] { "_id", "name"},
    null,null, null, null, null);

That's nice, but what if I want to a "join" ? I need more than 1 table in my query.
Well, at beginning I found CursorJoiner. Nice, I can join 2 cursors. But what if I have 3 or more joins to do ??

In fact, the parameter "table " (function query) can contains many tables (not just one).
For example:


Cursor cursor = myDataBase.query(
    "myTableA a, myTableB b",
    new String[] { "a._id", "a.name", "b._id", "b.name"},
    "a.foreignKey = b._id",
    null, null, null, null);

That was not difficult, but the definition of the parameter "table " was not so good.

Another solution would be to use SQLiteQueryBuilder.


SQLiteQueryBuilder myQuery = new SQLiteQueryBuilder();
myQuery.setTables("myTableA, myTableB");
myQuery.appendWhere("a.FK = b._id");
Cursor cursor = myQuery.query(myDataBase, null, null, null, null, null, null);

Android: add xml layout dynamically

2010-03-15T08:58:00.000-07:00

For the application I'm creating, the user can use "search" function. This function will return a list of castles.
Here is the XML to display one result (/res/layout/element_result.xml). There is 1 button, 2 text fields and 1 image :



android:id="@+id/layoutElement"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
>
             android:id="@+id/btnGo"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="@string/go"
       android:layout_alignParentTop="true"
       android:layout_alignParentRight="true"
      >
      
             android:id="@+id/description"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:layout_below="@+id/presentation"
       android:layout_alignLeft="@+id/presentation"
      >
      
             android:id="@+id/presentation"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:layout_alignParentTop="true"
       android:layout_toRightOf="@+id/image"
      >
      
             android:id="@+id/image"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:layout_alignParentTop="true"
       android:layout_alignParentLeft="true"
      >

Then, I created a XML layout (/res/layout/results.xml) who will contain the list of results. That means, there will be many times element_result.xml inside results.xml. There is a scrollView and a table layout.



android:id="@+id/widget28"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
>
  android:id="@+id/scrollResult"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:scrollbars="horizontal"
 android:layout_above="@+id/btnBack"
 android:layout_alignParentLeft="true"
 >
        android:id="@+id/myTableLayout"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      >  
  
 
 
  android:id="@+id/btnBack"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:text="@string/back"
 android:layout_alignParentBottom="true"
 android:layout_alignParentLeft="true"
 >

Ok, our views are ready. Now how to use them in Java. I read this blog, and that helps me a lot : Android LayoutWidth being disregarded by cascaded use of LayoutInflater.

Here is my activity file:


public class ResultActivity extends Activity{

 public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState);
        // "results" is for the xml file "results.xml"
        setContentView(R.layout.results);
  
        addElementResult();
 }
 
 public void addElementResult() {
        // "myTableLayout" is the id of the element in results.xml
        TableLayout tl = (TableLayout)findViewById(R.id.myTableLayout);
        // we will use service from inflater 
        LayoutInflater inflater = (LayoutInflater)getSystemService(LAYOUT_INFLATER_SERVICE);
  
        //doing a loop to add many times the same xml
        for(int i = 0; i < 17; i++) {
                 // "element_result" is the name of the xml file "element_result.xml". 
                 // Create the itemView who will be added.
                 // itemView = element_result.xml
                 View itemView = inflater.inflate(R.layout.element_result, null);
                 // get the textView, and set the text to something
                 TextView t1 = (TextView) itemView.findViewById(R.id.presentation); 
                 t1.setText("something" + i);
   
                 TextView t2 = (TextView) itemView.findViewById(R.id.description); 
                 t2.setText("oh oh oh" + i);

                 //add the itemView
                 tl.addView(itemView, new TableLayout.LayoutParams(
                   LayoutParams.FILL_PARENT, 
                   LayoutParams.WRAP_CONTENT));
        }
  }
}

So the result will look like that :

Note: in results.xml, I created a scrollView because if there is 20 results, the user should be able to scroll down to see all the results.
Note: I used "tableLayout" to be able to add results one under another one.

Android: main.out.xml error

2010-03-09T08:27:00.000-08:00

So it's been long time, I'm not doing Ruby anymore.
Now, for myself, I decided to create an Android application. At first, I wanted to create an Iphone application, but only people having a Mac can use the SDK... So let's use the Android SDK!
After doing the tutorial Hello World (see here), I started doing my application. And after a few minutes I had an error...


[2010-03-09 11:32:04 - shiro]Error in an XML file: aborting build.
[2010-03-09 11:32:05 - shiro]res\layout\main.xml:0: error: Resource entry main is already defined.
[2010-03-09 11:32:05 - shiro]res\layout\main.out.xml:0: Originally defined here.
[2010-03-09 11:32:05 - shiro]D:\workspace\shiro\res\layout\main.out.xml:1: error: Error parsing XML: no element found

For information, I'm using Eclipse. Why when I click on "run" I have this error ? Why Eclipse is creating a new file "main.out.xml" and then complain about it ? My application is really small, I didn't write any line of code in my main activity...

Well the error is simple, and it's not related to the application directly. It's a problem with Eclipse. To run the application, I must select the project (root folder) in the left column and then I can click on "run".

I had this error, because I was running the "main.xml". So Eclipse could not do anything with that.
Here is a noobie error, but it was difficult to find the solution...
I guess the next post will also concern Android application. It's always fun to discover new things :)

Install Tomcat on Windows 7

2009-11-03T12:20:00.001-08:00

I decided to install Tomcat (6.0) on Windows 7 for a project.

I downloaded "apache-tomcat-6.0.20.exe" directly from Tomcat website.

I installed it on "d:\".

Then I started it, but nothing happen, it was always at "stopped".
I check the log file, and I could see "[error] Failed creating java C:\Program Files\Java\jre6\bin\client\jvm.dll"

Copy the file msvcr71.dll (C:\Program Files\Java\jre6\bin\msvcr71.dll) to D:\Tomcat 6.0\bin

This website help me to find this solution: http://mandown.co.nz/development/getting-tomcat-apache-to-run-on-microsoft-windows-7/

If this didn't help you, you can have a look here: http://www.mkyong.com/tomcat/tomcat-error-prunsrvc-failed-creating-java-jvmdll/

update rubygems

2009-07-29T22:38:00.000-07:00

I tried to update rubygems on CentOs but could not.
First, I asked help to my friend Google and found this site: http://rubygems.org/read/chapter/3
It worked well on one computer but on another one I had this error:

/usr/lib/ruby/site_ruby/1.8/rubygems.rb:578:
in 'report_activate_error': could not find RubyGem session (>= 0) (Gem::LoadError)

I tried many things until I realized that "session" is actually a gem!
So let's do:

gem install session

Another error "could not find RubyGem hoe-seattlerb..."
So let's do:

gem install hoe-seattlerb

Same error with "hoe". But this one is tricky, because hoe need rubygems > 1.3.1, but to install rubygems 1.3.5 we need hoe!

update_rubygems
/usr/lib/ruby/site_ruby/1.8/rubygems.rb:578:
in `report_activate_error’: Could not find RubyGem hoe (>= 2.3.0) (Gem::LoadError)

gem install hoe
ERROR:  Error installing hoe:
      hoe requires RubyGems version >= 1.3.1

I tried to do (wihout success):

gem install rubygems-update #by default, it installs the latest version which is 1.3.5 now
update_rubygems

The problem is in version 1.3.5! First remove all rubygems:

gem uninstall rubygems-update

#Then
gem install rubygems-update -v 1.3.4
update_rubygems

#Then you can install hoe
gem install hoe

I lost so many hours for this stupid mistake...

insert date in sqlserver

2009-06-25T00:31:00.000-07:00

Recently I saw a strange behavior, and I don't know why. When I create a new object model and set its attributes, if I set the date, then in the DB it shows me the day before.

For example:


abc = ABC.find(:first, :conditions => "id = 1")
puts abc["date"] # 2009-06-25

#let's create a new object 'model' and set the same date as ABC
model = Model.new
model.date = abc["date"]
model.name = "a name"
model.save!

After, in Sqlserver management studio:


select * from model;

--date = 2009-06-24 15:00:00:000
--name = "a name"

So why it's not the 25th?? Is there a bad configuration somewhere? Well, I don't know. When I have more time, I'll try to understand why, but for now, to avoid this problem, I'm doing the following:


model.date = "#{abc["date"] }"

asynchrone Ajax query problem

2009-06-17T22:45:00.000-07:00

Can you find what's wrong in this code:


function example(event){
   for(i = 1; i < array.length; i++){
      new Ajax.Request(url, {
         method: 'put',
         postBody: someParam,
         onSuccess: function(transport){
            $(array[i]).innerHTML = "updated!";
         },
         onFailure: function(transport){
            //do something
         }
      });
   }
}

Description: let's say the array elements are all IDs of some tags "div". There is a loop, for each element an ajax request is send.
Hint: The "a" of Ajax stands for "asynchronous".
So where is the problem?

The problem is here:

$(array[i]).innerHTML = "updated!";

Why? Because we use "i"! Let's say the array has 10 elements. First (asynchronous) request is send (i=1), so our controller is working, and at the same time the loop continue, so now i=2, another Ajax request is send and so on. Now i=4 and... oh! the controller just finished is work for the first request, so the function onSucces is called, and then $(array[i]).innerHTML = "updated!". But "i" is 4 now! It's not 1 ! So we write "updated!" in the wrong div.

Here is my solution (maybe not the best one), I send "i" as a parameter to the controller and the controller return it.


function example(event){
   for(i = 1; i < array.length; i++){
      new Ajax.Request(url, {
         method: 'put',
         postBody: i, //send "i"
         onSuccess: function(transport){
            //get the response
            original_i = transport.responseJSON;

            $(array[original_i]).innerHTML = "updated!";
         },
         onFailure: function(transport){
            //do something
         }
     });
   }
}

Insuide the controller:


def my_controller
   post_data = request.raw_post #here we received "i"
   ....
   ....
   ....
   render :text => post_data #and we return it
end

Open flash chart save image (ruby+IE6)

2009-06-16T01:33:00.000-07:00

Presentation: one of my tasks was to implement a feature to print a flash chart. To generate the chart, I'm using Open Flash chart 2, great open source, free, library to draw chart dynamically. I downloaded it from PullMonkey website (because I'm working on Ruby).

Now let's try to print the chart. After the chart is generated (can't print if no render), we can get the image as binary:


document.getElementById('divfMyChart').get_img_binary()
//return a base 64 image, something like this: R0lGODlhFGHGGHRGH..... (very long string)

More info about base64. And here is an example of a base64 image:

If your web site support only FireFox and IE8 (and higher) that's perfect, because there is no problem! Here is the code, it will create a new window with the image:


img_src = document.getElementById('divOfMyChart').get_img_binary();
img_tag = "";
var img_win = window.open("", null);
with(img_win.document) {
write("my image" + img_tag + ""); } //change "t-itle" for "title"

You can see a more complete examples here.
Now if you open your web page with IE6 or IE7 it won't work! Why? Now begin the most interesting part of this post.
Well, it's not working because IE6 and IE7 don't support base64 format. It's not even a problem of your server, so you can not do anything except to change your source code.
I could see there is a library in PHP who can create an image from base64 image (base64_encode($string);).
So is there a similar library in Ruby? Yes there is! It's RMagick. An interface to the ImageMagick and GraphicsMagick image processing libraries. Supports over 100 image formats, including GIF, JPEG, PNG.

Download RMagick (current version 2.9.2): http://rubyforge.org/projects/rmagick/
If you're using Windows, download "rmagick-win32"!
Extract the files from the archive, and read README.html. Please follow the "Installation instructions". It's easy to install. RMagick requires ImageMagick or GraphicsMagick, so installed one (only one!). You can find the installation files in RMagick website.

And we need something else, the PNG library: http://www.libpng.org/pub/png/pngcode.html
PNG library is divided into 2 libraries :
zlib:Zlib is designed to be a free, general-purpose, legally unencumbered -- that is, not covered by any patents -- lossless data-compression library for use on virtually any computer hardware and operating system.
Download "zlib compiled DLL, version 1.2.3": http://www.zlib.net/ Extract the files and read USAGE.txt. It's easy to install: copy ZLIB1.DLL to the SYSTEM or the SYSTEM32 directory.

libpng:This is an open source project to develop and maintain the reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files.
download "libpng-1.2.37-setup.exe": http://sourceforge.net/project/showfiles.php?group_id=23617&package_id=16183 and install it.

So now you have everything!
We create a JS function who will send an ajax request (with the binary image) to the controller. The controller will create an image (jpg) on the server and return the path to this image. Then the JS function will create a popup to show the image.
In my view:


function printChart(event){
new Ajax.Request(urlForPrintImage, {
        method: 'put',
        postBody: document.getElementById('divOfMyChart').get_img_binary(),
        onSuccess: function(transport){
            image_path = transport.responseText;

            img = "";
            var img_win = window.open("", null);
            with(img_win.document) {
                write("My image" + img + ""); } //change "t-itle" for "title"
        },
        onFailure: function(transport){}
    });
}

In my controller:


require 'base64'
require 'rubygems'
require 'RMagick'

def print_image
        #get the parameter sent by ajax query
        png_data = request.raw_post

        #file name and path for the image file
        #(you have to change this depending of your routes)
        file_name = "myPath/chart.jpg"

        #decode the binary image with Base64
        blob = Base64.decode64(png_data)

        #use RMagick to create an image from the blob
        image = Magick::Image.from_blob(blob).first
        #save the file on the server
        image.write(file_name){  self.quality = 100    }

        #return the file path
        render :text => file_name
end

Why?

2008-10-29T06:18:00.000-07:00

In this blog I'll talk about the problems I had to face during my work.
I'm working for the industry of software development since 2005 as same time as I'm studying software engineering in Canada. I worked for 4 different companies.
First one was as an intern, only for 4 months. It's a small company, around 10 employees, I did some JSP, Java and Javascript.
My second experience was in a department of a university, we were a group of 12 peoples. I did mainly Java for 2 years as intern, part time and full time.
My third experience was in a consulting company, around 43 employees. I did some C++, C# and Biztalk.
Finally, my current work (as intern) is in Tokyo. We are 9 full time workers plus some part time students. I'm coding in Ruby (and use the framework Rails).

The purpose of this blog is to expose all the problems I faced during my work and the solution.
I'm doing this blog because many time I looked for a solution on other blogs, and that was useful! So maybe, who knows, my blog could be useful to someone.

So currently, all the post will concern Ruby and Rails.
Link for Ruby : http://www.ruby-lang.org/en/
Link for RoR : http://www.rubyonrails.org/