Strange error in running Phusion Passenger

If you have trouble starting passenger for your Rails application, check your httpd log file, usually at /var/log/httpd/error_log for something looks like this:

*** Passenger ERROR (ext/common/ApplicationPoolServer.h:643):
Cannot execute /usr/lib/ruby/gems/1.8/gems/passenger-2.2.4/ext/apache2/ApplicationPoolServerExecutable: Permission denied (13)

The solution is to run:

setenforce Permissive

or

/usr/sbin/setenforce Permissive

You may learn more about this at http://aproxacs.blog.qrobo.com/tag/selinux/

Problem with installing Passenger (mod_rails)?

A common problem you may find when installing passenger is it can’t find the APR development headers. A quick fix worked for me is to run:

export APXS2=/usr/local/apache2/bin/apxs

then everything works just fine.

Ruby code to convert country name to 2-letter code

You probably need this if you use Rails country_select helper for your country dropdown list. Many API requires a 2-letter country code instead of country names. Here is a piece of code can do just that:


# convert country name to country code
COUNTRY_CODES = {
'AF'=>'Afghanistan',
'AL'=>'Albania',
'DZ'=>'Algeria',
'AS'=>'American Samoa',
'AD'=>'Andorra',
'AO'=>'Angola',
'AI'=>'Anguilla',
'AQ'=>'Antarctica',
'AG'=>'Antigua And Barbuda',
'AR'=>'Argentina',
'AM'=>'Armenia',
'AW'=>'Aruba',
'AU'=>'Australia',
'AT'=>'Austria',
'AZ'=>'Azerbaijan',
'BS'=>'Bahamas',
'BH'=>'Bahrain',
'BD'=>'Bangladesh',
'BB'=>'Barbados',
'BY'=>'Belarus',
'BE'=>'Belgium',
'BZ'=>'Belize',
'BJ'=>'Benin',
'BM'=>'Bermuda',
'BT'=>'Bhutan',
'BO'=>'Bolivia',
'BA'=>'Bosnia And Herzegovina',
'BW'=>'Botswana',
'BV'=>'Bouvet Island',
'BR'=>'Brazil',
'IO'=>'British Indian Ocean Territory',
'BN'=>'Brunei',
'BG'=>'Bulgaria',
'BF'=>'Burkina Faso',
'BI'=>'Burundi',
'KH'=>'Cambodia',
'CM'=>'Cameroon',
'CA'=>'Canada',
'CV'=>'Cape Verde',
'KY'=>'Cayman Islands',
'CF'=>'Central African Republic',
'TD'=>'Chad',
'CL'=>'Chile',
'CN'=>'China',
'CX'=>'Christmas Island',
'CC'=>'Cocos (Keeling) Islands',
'CO'=>'Columbia',
'KM'=>'Comoros',
'CG'=>'Congo',
'CK'=>'Cook Islands',
'CR'=>'Costa Rica',
'CI'=>'Cote D\'Ivorie (Ivory Coast)',
'HR'=>'Croatia (Hrvatska)',
'CU'=>'Cuba',
'CY'=>'Cyprus',
'CZ'=>'Czech Republic',
'CD'=>'Democratic Republic Of Congo (Zaire)',
'DK'=>'Denmark',
'DJ'=>'Djibouti',
'DM'=>'Dominica',
'DO'=>'Dominican Republic',
'TP'=>'East Timor',
'EC'=>'Ecuador',
'EG'=>'Egypt',
'SV'=>'El Salvador',
'GQ'=>'Equatorial Guinea',
'ER'=>'Eritrea',
'EE'=>'Estonia',
'ET'=>'Ethiopia',
'FK'=>'Falkland Islands (Malvinas)',
'FO'=>'Faroe Islands',
'FJ'=>'Fiji',
'FI'=>'Finland',
'FR'=>'France',
'FX'=>'France, Metropolitan',
'GF'=>'French Guinea',
'PF'=>'French Polynesia',
'TF'=>'French Southern Territories',
'GA'=>'Gabon',
'GM'=>'Gambia',
'GE'=>'Georgia',
'DE'=>'Germany',
'GH'=>'Ghana',
'GI'=>'Gibraltar',
'GR'=>'Greece',
'GL'=>'Greenland',
'GD'=>'Grenada',
'GP'=>'Guadeloupe',
'GU'=>'Guam',
'GT'=>'Guatemala',
'GN'=>'Guinea',
'GW'=>'Guinea-Bissau',
'GY'=>'Guyana',
'HT'=>'Haiti',
'HM'=>'Heard And McDonald Islands',
'HN'=>'Honduras',
'HK'=>'Hong Kong',
'HU'=>'Hungary',
'IS'=>'Iceland',
'IN'=>'India',
'ID'=>'Indonesia',
'IR'=>'Iran',
'IQ'=>'Iraq',
'IE'=>'Ireland',
'IL'=>'Israel',
'IT'=>'Italy',
'JM'=>'Jamaica',
'JP'=>'Japan',
'JO'=>'Jordan',
'KZ'=>'Kazakhstan',
'KE'=>'Kenya',
'KI'=>'Kiribati',
'KW'=>'Kuwait',
'KG'=>'Kyrgyzstan',
'LA'=>'Laos',
'LV'=>'Latvia',
'LB'=>'Lebanon',
'LS'=>'Lesotho',
'LR'=>'Liberia',
'LY'=>'Libya',
'LI'=>'Liechtenstein',
'LT'=>'Lithuania',
'LU'=>'Luxembourg',
'MO'=>'Macau',
'MK'=>'Macedonia',
'MG'=>'Madagascar',
'MW'=>'Malawi',
'MY'=>'Malaysia',
'MV'=>'Maldives',
'ML'=>'Mali',
'MT'=>'Malta',
'MH'=>'Marshall Islands',
'MQ'=>'Martinique',
'MR'=>'Mauritania',
'MU'=>'Mauritius',
'YT'=>'Mayotte',
'MX'=>'Mexico',
'FM'=>'Micronesia',
'MD'=>'Moldova',
'MC'=>'Monaco',
'MN'=>'Mongolia',
'MS'=>'Montserrat',
'MA'=>'Morocco',
'MZ'=>'Mozambique',
'MM'=>'Myanmar (Burma)',
'NA'=>'Namibia',
'NR'=>'Nauru',
'NP'=>'Nepal',
'NL'=>'Netherlands',
'AN'=>'Netherlands Antilles',
'NC'=>'New Caledonia',
'NZ'=>'New Zealand',
'NI'=>'Nicaragua',
'NE'=>'Niger',
'NG'=>'Nigeria',
'NU'=>'Niue',
'NF'=>'Norfolk Island',
'KP'=>'North Korea',
'MP'=>'Northern Mariana Islands',
'NO'=>'Norway',
'OM'=>'Oman',
'PK'=>'Pakistan',
'PW'=>'Palau',
'PA'=>'Panama',
'PG'=>'Papua New Guinea',
'PY'=>'Paraguay',
'PE'=>'Peru',
'PH'=>'Philippines',
'PN'=>'Pitcairn',
'PL'=>'Poland',
'PT'=>'Portugal',
'PR'=>'Puerto Rico',
'QA'=>'Qatar',
'RE'=>'Reunion',
'RO'=>'Romania',
'RU'=>'Russia',
'RW'=>'Rwanda',
'SH'=>'Saint Helena',
'KN'=>'Saint Kitts And Nevis',
'LC'=>'Saint Lucia',
'PM'=>'Saint Pierre And Miquelon',
'VC'=>'Saint Vincent And The Grenadines',
'SM'=>'San Marino',
'ST'=>'Sao Tome And Principe',
'SA'=>'Saudi Arabia',
'SN'=>'Senegal',
'SC'=>'Seychelles',
'SL'=>'Sierra Leone',
'SG'=>'Singapore',
'SK'=>'Slovak Republic',
'SI'=>'Slovenia',
'SB'=>'Solomon Islands',
'SO'=>'Somalia',
'ZA'=>'South Africa',
'GS'=>'South Georgia And South Sandwich Islands',
'KR'=>'South Korea',
'ES'=>'Spain',
'LK'=>'Sri Lanka',
'SD'=>'Sudan',
'SR'=>'Suriname',
'SJ'=>'Svalbard And Jan Mayen',
'SZ'=>'Swaziland',
'SE'=>'Sweden',
'CH'=>'Switzerland',
'SY'=>'Syria',
'TW'=>'Taiwan',
'TJ'=>'Tajikistan',
'TZ'=>'Tanzania',
'TH'=>'Thailand',
'TG'=>'Togo',
'TK'=>'Tokelau',
'TO'=>'Tonga',
'TT'=>'Trinidad And Tobago',
'TN'=>'Tunisia',
'TR'=>'Turkey',
'TM'=>'Turkmenistan',
'TC'=>'Turks And Caicos Islands',
'TV'=>'Tuvalu',
'UG'=>'Uganda',
'UA'=>'Ukraine',
'AE'=>'United Arab Emirates',
'UK'=>'United Kingdom',
'US'=>'United States',
'UM'=>'United States Minor Outlying Islands',
'UY'=>'Uruguay',
'UZ'=>'Uzbekistan',
'VU'=>'Vanuatu',
'VA'=>'Vatican City (Holy See)',
'VE'=>'Venezuela',
'VN'=>'Vietnam',
'VG'=>'Virgin Islands (British)',
'VI'=>'Virgin Islands (US)',
'WF'=>'Wallis And Futuna Islands',
'EH'=>'Western Sahara',
'WS'=>'Western Samoa',
'YE'=>'Yemen',
'YU'=>'Yugoslavia',
'ZM'=>'Zambia',
'ZW'=>'Zimbabwe'
}

class String
  def to_country_code
    COUNTRY_CODES.index(self)
  end

end

 

Never insert comments in ERB code

Never insert comments in ERB code in one line, such as:

<% if somecode # my comment… %>

If you have more stuff after this line, it will be all ignored by rails, causing many problems.

How to add initial files of RSpec for a new project

Follow these steps and you will have a basic skeleton of rspec workspace:
rails stuff
cd stuff
ruby script/plugin install svn://rubyforge.org/var/svn/rspec/tags/CURRENT/rspec
ruby script/plugin install svn://rubyforge.org/var/svn/rspec/tags/CURRENT/rspec_on_rails
script/generate rspec
script/generate rspec_scaffold Thing name:string

How to get real self.id in :finder_sql

Sometimes you will have to use :finder_sql for complicated queries in an activerecord association, there is just simply no way around it. Now it’s important to get the calling model’s id, self.id, to construct correct SQL statements.

The problem is if you’re not careful, you will get weird id number for #{self.id}, which is actually the object_id, not the id from the database record.

The trick is not let #{self.id} to be evaluated immediately in the :finder_sql, but rather later when the whole sql is generated. For example, instead of using

:finder_sql => ".... t.user_id = #{self.id} ..."

use

'.... t.user_id = #{self.id} ...'

Notice it’s in single quote now. That will cause self.id to return the real id from the database, not the object_id.

How to use multiple submit buttons for Ajax forms(form_remote)

The problem with form submission through an ajax remote call in Rails is that the Form.serialize doesn’t know which submit button is clicked, and it doesn’t include the value of the button clicked in the submission data.

There are many ways to do this, including extending the native Rails submit_tag helper, but the potential problem with that is all submit_tag will generate the extra code for handling the multiple submit buttons, which isn’t something you might want.

An easy way(especially you just have one or two forms that you need to do this) is to just add a hidden field in the form, and then in your extra submit button’s onclick event, set that hidden field value to whatever you want, so that in the controller end, you can just check for that hidden field.

Example:

 

<%= submit_tag “Save changes” %> <%= hidden_field_tag(:goal_status, “”) %> <%= submit_tag “Accomplished”, nclick => “$(‘goal_status’).value = ‘done’” %>

Solution to error from “gem install mysql”

On Mac/CentOS, sometimes you get errors when trying to “gem install mysql”.
To fix this, if your Mac is intel based, do:

$ sudo -s
$ ARCHFLAGS=”-arch i386″ gem install mysql — –with-mysql-dir=/usr/local/mysql

you might want to change “/usr/local/mysql” part to whatever is correct on your system.