Mysql has a nice “if exists” addition to the drop table statement. If the table to be dropped does not exists, it doesn’t raise an exception but only creates a warning.
In Oracle RDMBS you can emulate this behavior like so:
BEGIN execute immediate 'drop table INSERT_TABLE_NAME_HERE'; EXCEPTION WHEN others THEN IF SQLCODE != -942 THEN RAISE; END IF; END; /
Ugly, but it works very well.
Java has the nice Iterable interface (since Java 5, i guess) that allows object oriented loops like
List<String> strings = new ArrayList<String>(); for(String string : strings) System.out.println(string);
but guess what, a simple array is not iterable…
In case you need one, feel free to use this one:
package ac.simons; import java.util.Iterator; public class IterableArray<T> implements Iterable<T> { private class ArrayIteratorImpl implements Iterator<T> { private int position = 0; @Override public boolean hasNext() { return data != null && this.position < data.length; } @Override public T next() { return data[position++]; } @Override public void remove() { throw new UnsupportedOperationException(); } } private final T[] data; public IterableArray(T[] data) { this.data = data; } @Override public Iterator<T> iterator() { return new ArrayIteratorImpl(); } }
Some would say, i have 3 problems 
private final static Pattern placeholder = Pattern.compile("#\\{(\\w+?)\\}");
won’t match “Mot#{ö}rhead” for example.
To replace the word character \w you either need the list of possible unicodeblocks like [\p{InLatin}|\p{InEtc}] (you get the codes for the blocks through “Character.UnicodeBlock.forName” or you’re lazy like me and just use the dot:
private final static Pattern placeholder = Pattern.compile("#\\{(.+?)\\}");
Oh what a day… :/
The default behavior for quite a long time was :hard_breaks in the textilize helper method in rails.
Hard Breaks means: All line breaks are turned into <br />’s.
Somebody changed the textilize helper in “actionpack-2.3.4/lib/action_view/helpers/text_helper.rb” in 2.3.4 and added the ability to pass some options but broke the default behavior here:
def textilize(text, *options) options ||= [:hard_breaks] # ...
Options will never be null.
I fixed this by monkey patching the module through the following code in config/initializers/textilizepatch.rb
module ActionView module Helpers module TextHelper def textilize(text, *options) options = [:hard_breaks] if options == nil || options.size == 0 if text.blank? "" else textilized = RedCloth.new(text, options) textilized.to_html end end end end end
Such changes should be tested… *grml*
You can use
RAILS_DEFAULT_LOGGER.log "foobar" # or Rails.logger.log "blah"
outside a controller for logging.
By default, Rubys heredocs are interpreted as double-quoted strings, that is #{something} is evaluated, \r turns into newline and so forth.
You can change this behaviour by single quoting the heredoc identifier like so:
s = <<-'SINGLE_QUOTED' #{i'm not interpreted} SINGLE_QUOTED
Regarding my question on twitter about completely disabling the creation of stacktrace.log from a Grails application in production mode, here is my answer:
environments { production { log4j = { appenders { null name:'stacktrace' } } } development { } }
Be careful: This overwrites all other log4j closures that are made outside the environment specific settings. I found no solution for that.
Background: One of my Grails 1.1 app fails to start on a Tomcat application container deployed on an Oracle Enterprise Linux server because it fails to create the stacktrace.log.
What annoyed me is that i needed to dig around in the Grails source code to find the answer to my question in “src/groovy/org/codehaus/groovy/grails/plugins/logging/Log4jConfig.groovy” within the method “createFullstackTraceAppender()”. Should be stated in the documentation (perfect place here).
Edit: If your Grails 1.1 still fails to start(*) look out for xercesImpl.jar and xml-apis.jar or similar somewhere in your Tomcat 5 directory. These are some kind of Java 1.4 compatibility layers which break things in Grails 1.1. Oracle puts these into common/endorsed. After removing them, everything went fine.
(*) Exception was:
java.lang.RuntimeException: XPathFactory#newInstance() failed to create an XPathFactory for the default object model: http://java.sun.com/jaxp/xpath/dom with the XPathFactoryConfigurationException: javax.xml.xpath.XPathFactoryConfigurationException: No XPathFctory implementation found for the object model: http://java.sun.com/jaxp/xpath/dom
Ruby on Rails I18n infrastructure did a great job to internationalization in Rails applications. Most things work right out of the box.
Daily Fratze is fully internationalized and i wanted to use ordinal day numbers in the English version. Pity, there is no template for strftime that works that way.
As i already hat monkey patched a “t” method to all date and time related classes, i came up with the following solution:
Parallel to “en.yml” i now have “en.rb” in my locales folder which gets loaded in environment.rb via
config.i18n.load_path += Dir[File.join(RAILS_ROOT, 'app', 'locales', '*.{yml,rb}')]
The en.rb files defines some procs as translation values like so:
{ :'en' => { :date => { :formats => { :dmy_with_long_month => lambda { |date| "%B #{date.day.ordinalize}, %Y" }, } }, :time => { :formats => { :dmy_with_long_month => lambda { |date| "%B #{date.day.ordinalize}, %Y" }, :dmy_with_full_day_and_long_month_and_time => lambda { |date| "%A, %B #{date.day.ordinalize}, %Y at %H:%M" } } } } }
Used with the standard I18n tools you’ll end up with the string representation of the proc object. Useless
So time for monkeypatching like so:
module DateTimeSupport def t(format = nil) type = self.respond_to?(:sec) ? 'time' : 'date' formats = I18n.translate(:"#{type}.formats") format = formats[format.to_sym] if formats && formats[format.to_sym] I18n.localize(self, :format => format.respond_to?(:call) ? format.call(self) : format) end end class Time include DateTimeSupport end class Date include DateTimeSupport end class DateTime include DateTimeSupport end class ActiveSupport::TimeWithZone include DateTimeSupport end
Code resides in a file in config/initializers and gets loaded automatically. It adds a t method to all date and time related classes. The method tries to look up the translation of format just like I18n/Simple does.
If it is proc, it gets called and then passed to I18n, otherwise it the original parameter is used.
That way the t method can use “dmy_with_long_month”, :dmy_with_long_month and any other arbitrary format like “%B %Y” that is not defined in any language file.
Just some snippets from the doku that I tend to forget:
Run grails on a different port:
grails -Dserver.port=9090 run-appRun grails with a different environment:
grails prod run-app // production grails -Dgrails.env=mycustomenv run-app // mycustomenv
If you followed the instructions here and used the method named PDF::Writer (Austin Ziegler), you we’re out of luck when Rails 2.1 appeared.
With Rails 2.2.2 once again the rendering mechanism seems to have changed big time and my previous post on how to make the pdf/writer gem work with a custom template handler doesn’t work anymore.
With the help of Josh Peek i was able to fix this. He gave me the following code to enable a rpdf template handler with pdf-writer:
module ActionView # :nodoc: require 'pdf/writer' class PDFRender < ActionView::TemplateHandler PAPER = 'A4' include ApplicationHelper include ActionView::Helpers::TranslationHelper include ActionView::Helpers::AssetTagHelper include ActionView::Helpers::TextHelper include ActionView::Helpers::TagHelper include ActionView::Helpers::UrlHelper def self.call(template) "ActionView::PDFRender.new(self).render(template, local_assigns)" end def initialize(action_view) @action_view = action_view end # Render the PDF def render(template, local_assigns = {}) @action_view.controller.headers["Content-Type"] ||= 'application/pdf' # Retrieve controller variables @action_view.controller.instance_variables.each do |v| instance_variable_set(v, @action_view.controller.instance_variable_get(v)) end pdf = ::PDF::Writer.new( :paper => PAPER ) pdf.compressed = true if RAILS_ENV != 'development' eval template.source, nil, '' pdf.render end end end ActionView::Template.register_template_handler 'rpdf', ActionView::PDFRender
Just drop this under config/initializers and you’re fine.