There is a simple command to renew (restart, or rather reflush) the ethernet connection, that will result in the renewing of DHPC IP. Assuming your network connection is eth0 (you can check it with ifconfig command), just type:

ifdown eth0
ifup eth0

And that’s all! The new IP would be printed in the output of the last command.

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As I have decided to use PRAWN as a PDF generator (with prawn_rails gem – I can really recommend, works with Rails3), I had to choose between recreating the form or just filling in the form that was ready. As time=money, I decided to go for the second possibility.

1. I converted the pdf form to JPG (300 dpi resolution, no compression).

2. I needed A4 page size, so I also need to scale my image. In my example_document.pdf.prawn, I should put:

bg = "#{RAILS_ROOT}/public/pdf/pdf_bg.jpg"

prawn_document (
    :filename=>'foo.pdf',
    :page_size=> "A4",
    :margin => 0) do |pdf|
      pdf.image bg,
        :at  => [0, Prawn::Document::PageGeometry::SIZES["A4"][1]],
        :fit => Prawn::Document::PageGeometry::SIZES["A4"]
  pdf.text "This is pdf with background image ready to fill in"
end

The code above imports the image and positions it in the right left corner (remember! bounding box in pdf has its origin [0,0] in BOTTOM LEFT corner of the page). The size of A4 is set as constant by PRAWN (nice of them, isn’t it?). You can access it by Prawn::Document::PageGeometry::SIZES array. The full list of available page sizes you can find in PRAWN source code at https://github.com/sandal/prawn/blob/master/lib/prawn/document/page_geometry.rb.

3. Now one has to play around a little bit in order to position the data obtained from db in right positions.

Good luck!

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gem 'example', :git => "git://github.com/gituser/example.git"

While bundle install, I got the error message:

fatal: Unable to look up github.com (port 9418) (Name or service not known)

I tried git clone -q git://github.com/gituser/example.git or rails plugin install git://github.com/gituser/example.git, still I got the same error message. It seems that Github has recently updated DNS and the changes haven’t propagated yet. You can use a workaround:

1. Run ping github.com and read the current IP
2. Go to /etc/hosts on your Rails server (assuming its Linux) and add the following line:

   207.97.227.239 github.com wiki.github.com gist.github.com assets0.github.com assets1.github.com assets2.github.com assets3.github.com
   

   where instead of 207.97.227.239 type it the current Github IP

It is suggested to remove this line once the DNS is up and working again.

Source

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1. PIK: Multiple Ruby versions for Windows
2. RubyGems warning/error: Gem::Specification# default_executable = is deprecated with no replacement. It will be removed on or after 2011-10-01.

NOTE: Gem::Specification# default_executable = is deprecated with no replacement. It will be removed on or after 2011-10-01.

This is connected with the recent policy of RubyGems team – read the official statement.

They have deprecated 22+ methods! It will take some time for Gem authors to update… Before then, you may run:

gem pristine --all --no-extensions

to get most recent and thus some of the warrnings gone…

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1. RoR: Railroad plugin with Rails 2.3.5 on Windows error
2. Github error – fatal: Unable to look up github.com (port 9418) (Name or service not known)
3. PIK: Multiple Ruby versions for Windows

There is a solution: Ruby Version Manager (RVM)… but not for windows For the latter, you should use PIK gem https://github.com/vertiginous/pik. The installation is pretty easy, just follow the tutorial at github repo step by step.

PROBLEM

So install PIK, add all ruby versions you want to, use the one you need. But well, life is not that easy… Supposing you’ve got some more complicated gem dependencies in your gemfile, when you try to run:

rake db:migrate

you will probably see the message like below:

There was an error. Error - can't dup NilClass /gemname/

or, in case you use sqlite3:

Unknown method sqlite3_backup_finish in sqlite3.dll.

SOLUTION

1. Set gem_home for the choosen ruby version. Probably the path to install gems isn’t set to unique for every Ruby version you’ve installed. This may be highly confusing and cause some errors if you use different gem versions for Rails 2.3.x and Rails3 (which is the case in 99% of cases).

• Supposing you work on Ruby 1.9.2, you type: pik use 192.
• Then you can check where is current working dir: which ruby or which rails.
• Go to c:/Users/username/.pik/config.yml.
• Edit the proper line in YAML file adding the following lines to the chosen Ruby version

  :gem_home: !ruby/object:Pathname
      path: c:/users/greg/.pik/rubies/Ruby-192-p180
  

  So that the whole version definifion will look like:

  "192: ruby 1.9.2p180 (2011-02-18) [i386-mingw32]":
    :gem_home: !ruby/object:Pathname
      path: c:/users/greg/.pik/rubies/Ruby-192-p180
    :path: !ruby/object:Pathname
      path: C:/Users/Greg/.pik/rubies/Ruby-192-p180/bin
  

  Mind the spaces and tabs!

2. SQLite 3 for Windows needs some additional libraries. You can find them at http://www.sqlite.org/download.html The solution is simple: download the sqlite3.dll and sqlite3.exe and copy it to your Ruby bin directiory, i.e. C:/Users/Greg/.pik/rubies/Ruby-192-p180/bin

I hope this was helpful and saved you some time of your life

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3. Alternative strings’s delimiter for Ruby (on Rails)

s1 = 'Hello!'
s2 = "This is a string.\n Calculations: 2+2=#{2+2}"

You can use both single and double quotes, however double quotes give you much more – expressions enclosed in #{} would be processed by Ruby before string is shown. Pretty cool, heh?
But I am sure most of you have already known that. Let’s proceed than: consider you have a string, that contains many mixed quotes (‘) and double quotes („). How to write it, if the same marks (‘) and („) are considered as string delimiters? Of course you can concatenate string step by step delimiting single quote with double quoted and vice versa, but this is painful. There is a better solution:

Custom string delimiters

Ruby provides a mechanism to define custom string delimiter both as single quoted %q and double quoted %Q string alternative. Let’s see examples:

s3 = %q[My dog's name is George "Jonny" the Second] #single quoted string
s4 = %Q/One can define a string by s = "String content" or s2 = 'string2 content'\n Calculations: 2+2=#{2+2}/

So as string delimiters one can use a nonalphanumeric character that should go right after %q or %Q and the string should be terminated with the same character. In case you use brackets, you should terminate the string with the corresponding closing bracket.

Operating system commands

Strings enclosed with backquotes or %x{} would be considered by Ruby as operating system commands. Just try:

puts (`calc`)

or

puts ("Current directory content is: #{%x/dir/}")

HEREDOCS

The last, but not least neat way to define long, multiline strings is so called HEREDOCS. Let’s see an example first:

LongString = <<LINEEND
Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the
industry's standard dummy text ever since the #{15*100}s, when an unknown printer took a galley of type
and scrambled it to make a type specimen book. It has survived not only five centuries, but also the
 leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s
 with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop
publishing software like Aldus PageMaker including versions of Lorem Ipsum.
LINEEND

The HEREDOCs string starts with specifying the end marker (in my example: LINEEND). Everything you write would be treated as doublequoted string till you write the end marker (should be placed nonindendet in a new line).

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3. jQuery AJAX in Ruby on Rails

How to check if element in DOM exists, i.e. if the selector $(‘.some_class’) is not empty?

The simplest:

if ($('.some_class')) {
   //some action
}

will not work!

The correct condition uses the .lenght function:

if ($('.some_class').length > 0) {
   //some action
}

Note no brackets after .length.

How to check if JavaScript object’s property exists?

This is tricky, as there are two types of properties: own properties and prototype properties. Not going into details, we can assume, that own properties are the one that are for example serialized by JSON, and prototype properties are the one that can be empty or not, but are given in the object’s definition.

So, in most cases you want to check if the own property exists for the given object. This can be obtained using the hasOwnProperty() method:

if (the_object.hasOwnProperty("name)) {
   //some action
}

If you only want to check whether there is the prototype property, you may use in operator to determine the existence of the property:

if ("name" in the_object)) {
   //some action
}

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It is really easy to implement, quite well documented and really easy to style (through jQuery UI themes and its excellent themeroller).

I was working on a Joomla-PHP-MySQL project. I have successfully enabled the extended show functionality, adding edit option also went smoothly. However, I got a little bit stuck while trying to enable Search. Basing on demo examples and some blogs, I have managed to develop a piece of code that successfully made the search work like a charm. Below you’d find a php file responsible for returning the get xml data request from jqgrid.

<?php
$page = $_GET['page']; // get the requested page
$limit = $_GET['rows']; // get how many rows we want to have into the grid
$sidx = $_GET['sidx']; // get index row - i.e. user click to sort
$sord = $_GET['sord']; // get the direction
if(!$sidx) $sidx =1;

//array to translate the search type
$ops = array(
    'eq'=>'=', //equal
    'ne'=>'<>',//not equal
    'lt'=>'<', //less than
    'le'=>'<=',//less than or equal
    'gt'=>'>', //greater than
    'ge'=>'>=',//greater than or equal
    'bw'=>'LIKE', //begins with
    'bn'=>'NOT LIKE', //doesn't begin with
    'in'=>'LIKE', //is in
    'ni'=>'NOT LIKE', //is not in
    'ew'=>'LIKE', //ends with
    'en'=>'NOT LIKE', //doesn't end with
    'cn'=>'LIKE', // contains
    'nc'=>'NOT LIKE'  //doesn't contain
);
function getWhereClause($col, $oper, $val){
    global $ops;
    if($oper == 'bw' || $oper == 'bn') $val .= '%';
    if($oper == 'ew' || $oper == 'en' ) $val = '%'.$val;
    if($oper == 'cn' || $oper == 'nc' || $oper == 'in' || $oper == 'ni') $val = '%'.$val.'%';
    return " WHERE $col {$ops[$oper]} '$val' ";
}
$where = ""; //if there is no search request sent by jqgrid, $where should be empty
$searchField = isset($_GET['searchField']) ? $_GET['searchField'] : false;
$searchOper = isset($_GET['searchOper']) ? $_GET['searchOper']: false;
$searchString = isset($_GET['searchString']) ? $_GET['searchString'] : false;
if ($_GET['_search'] == 'true') {
    $where = getWhereClause($searchField,$searchOper,$searchString);
}

// connect to the database
$dbhost = "host_address";
$dbuser = "db_user";
$dbpassword = "db_pass";
$database = "db_name";
$tablename
$db = mysql_connect($dbhost, $dbuser, $dbpassword)
or die("Connection Error: " . mysql_error());

mysql_select_db($database) or die("Error conecting to db.");
mysql_set_charset('utf8',$database);
mysql_query("SET NAMES 'utf8'");
$result = mysql_query("SELECT COUNT(*) AS count FROM $tablename");
$row = mysql_fetch_array($result,MYSQL_ASSOC);
$count = $row['count'];

if( $count >0 ) {
	$total_pages = ceil($count/$limit);
} else {
	$total_pages = 0;
}
if ($page > $total_pages) $page=$total_pages;
$start = $limit*$page - $limit; // do not put $limit*($page - 1)
$SQL = "SELECT field1, field2, field3, field4, field5 FROM $tablename "
.$where." ORDER BY $sidx $sord LIMIT $start , $limit";
$result = mysql_query( $SQL ) or die("Couldn?t execute query.".mysql_error());

if ( stristr($_SERVER["HTTP_ACCEPT"],"application/xhtml+xml") ) {
header("Content-type: application/xhtml+xml;charset=utf-8"); } else {
header("Content-type: text/xml;charset=utf-8");
}
$et = ">";

echo "<?xml version='1.0' encoding='utf-8'?$et\n";
echo "<rows>";
echo "<page>".$page."</page>";
echo "<total>".$total_pages."</total>";
echo "<records>".$count."</records>";
// be sure to put text data in CDATA
while($row = mysql_fetch_array($result,MYSQL_ASSOC)) {
	echo "<row id='". $row[field1]."'>";
	echo "<cell>". $row[field1]."</cell>";
	echo "<cell>". $row[field2]."</cell>";
	echo "<cell><![CDATA[". $row[field3]."]]></cell>";
	echo "<cell>". $row[field4]."</cell>";
	echo "<cell>". $row[field5]."</cell>";
	echo "</row>";
}
echo "</rows>";
?>

If you perform the search in jqgrid, the following variables are set in the request:

• _search = TRUE
• searchField – the name of the field defined in colModel
• searchString – the string typed in the search field
• searchOper – the operator choosen in the search field (ex. equal, greater than, …)

The $ops array converts the searchOper into the SQL-compatible command (equal -> ‘=’, greated or equal -> ‘>=’, etc.). The getWhereClause generated the WHERE piece of statement, including the modification of searchString in case of some types of search (ex. ‘%’ sign in case of LIKE). Then we just check if the _SEARCH variable is true, and if so the $where statement is added to the query. The rest of the code is just the same as in the jqgrid demo.

Good luck, in case of questions, drop a comment below.

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1. implement awesome_nested_set + rails-ckeditor + paperclip
2. find a ready-to-go solution

After a little bit of googling tens of out-of-date pages&blogs, I ended up on a great website http://www.whichrubycmsshouldiuse.com/ by Youssef Chaker.

I decided to give a try to BrowserCMS, as I can easily integrate it with exisiting project that only part is going to be controlled by CMS.

I have made my mind basing on two nice comparisons found on http://www.whichrubycmsshouldiuse.com/:

And:

I hope it will help you too!

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ruby script/plugin install git://github.com/iain/i18n_label.git

Now you should just add appropriate entries to your locale file. I’d explain it in the example below.
I have the following form to the model Post:

<% form_for :post do |f| -%>
  <%= f.error_messages %>

  <p><%= f.label :name %></p>
  <p><%= f.text_field :name %></p>

  <p><%= f.submit "Wyślij" %></p>
<% end -%>

I want the label :name to be automatically translated according to the entry in locales. Taking as an example polish locale pl.yml, we have to create new entry:

pl:
  activerecord:
    models:
      post: "Wiadomości"
    attributes:
      post:
        name: "Nazwa"

…and that’s all! After restarting the project, the form labels are successfully tanslated according to locale entries!

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2. Ruby on Rails CMS
3. Alternative strings’s delimiter for Ruby (on Rails)