3488 cards
View

Geordi 1.9 released

New features:

geordi delete_dumps [directory]

Recursively search for files ending in *.dump and offer to delete those. When no argument is given, two default directories are searched for dump files: the current working directory and ~/dumps (for dumps created with geordi).

geordi drop_databases

Delete local MySQL/MariaDB and Postgres databases that are not whitelisted.

Authentication is handled via PAM for Postgres and MariaDB, via .my.cnf with fallback to mysql -p for MySQL. Different connection methods can be chosen via …

Store MySQL passwords for development

On your local system that only hosts non-critical development data and only you have access to, you can store MySQL's root password in your home directory so you can use mysql commands without prompt for passwords, i.e. when doing batch processing.

Of course, this has security implications. The password must be stored in plain text, so this method is out of the question if there's any confidential data in your databases. Assuming diligent screen-locking, an encrypted hard disk and correct permissions set on your credential file, it shoul…

Repeats

Don't assign time values to date attributes

Do not pass times to date attributes. Always convert times to dates when your application uses time zones.

Background

A time-zoned Time attribute on a Rails record is converted to UTC using to_s(:db) to be stored, and converted back into the correct time zone when the record is loaded from the database. So when you are not on UTC, time objects will be converted as follows.

>> Time.current
=> Fri, 15 Mar 2013 11:56:03 CET +01:00
>> Time.current.to_s(:db)
=> "2013-03-15 10:56:03" # This is now UTC

Problem

That will…

Repeats

FileIO: Writing strings as Carrierwave uploads

When you have string contents (e.g. a generated binary stream, or data from a remote source) that you want to store as a file using Carrierwave, here is a simple solution.

While you could write your string to a file and pass that file to Carrierwave, why even bother? You already have your string (or stream).
However, a plain StringIO object will not work for Carrierwave's ActiveRecord integration:

>> Attachment.create!(file: StringIO.new(contents))
TypeError: no implicit conversion of nil into String

This is because Carrierwave ex…

Repeats

MySQL: Disable query cache for database profiling

If you want to see how long your database queries actually take, you need to disable MySQL's query cache. This can be done globally by logging into a database console, run

SET GLOBAL query_cache_type=OFF;

and restart your rails server.

You can also disable the cache on a per query basis by saying

SELECT SQL_NO_CACHE * FROM ...

You also probably want to disable Rails internal (per-request) cache. For this, wrap your code with a call to ActiveRecord::Base.uncached. For example, as an around_filter:

def disable_cache  ...
External contentRepeats

Rails SQL Injection Examples

This page lists many query methods and options in ActiveRecord which do not sanitize raw SQL arguments and are not intended to be called with unsafe user input. Careless use of these methods can open up code to SQL Injection exploits. The examples here do not include SQL injection from known CVEs and are not vulnerabilites themselves, only potential misuses of the methods.

Please use this list as a guide of what not to do.

Running Rails 2 apps with modern MariaDB SQL server

You might have some trouble running a Rails LTS 2 app with MySQL 5.7.

If you don't want to hack Mysql 5.6 into your modern Ubuntu or use the MySQL sandbox, you might want to try MariaDB 10.x.

MariaDB 10.x should work with both old and new Rails applications.

Switch to MariaDB

Remove MySQL:

```
sudo apt r…

Repeats

Common mistakes when storing file uploads with Rails

1. Saving files to a directory that is not shared between deploys or servers

If you save your uploads to a made up directory like "RAILS_ROOT/uploads", this directory goes away after every deploy (since every release gets a new). Also this directory is not shared between multiple application servers, so your uploads are randomly saved to one local filesystem or another. Fixing this afterwards is a lot of fun.

Only two folders are, by default, shared between our application servers and deployments: "RAILS_ROOT/storage" and `"RAILS…

Repeats

Rails: Adding view paths on the fly

Rails offers a way to prepend (or append) view paths just for the current request.

Example

A use case of this is a different set of view templates that should be used under certain circumstances:

class UsersController < ApplicationController

  before_action :prepare_views
  
  def index
    ...
  end    
  
  private
  
  def prepare_views
    if <condition>
      prepend_view_path Rails.root.join('app', 'views', 'special')
    end
  end
  
end

If <condition> is true, Rails will first look into app/views/special to find a…

Upgrading a Rails app to Cucumber 3

Upgrade gems

You need to update a lof gems. Make sure you don't have any version constraints in your Gemfile or your bundle update won't do anything!

Upgrade cucumber_priority:

bundle update cucumber_priority

Upgrade spreewald:

bundle update spreewald

Upgrade cucumber_factory:

bundle update cucumber_factory

Upgrade parallel_tests:

bundle update parallel_tests

Even on the latest version, parallel_tests will print some deprecation warnings due to using an older formatter A…

Delegating an instance method to a class method in Ruby

With ActiveSupport you can say:

class Robot
  def self.likes_humans?
    'Nope.'
  end

  delegate :likes_humans?, to: :class
end

Robot.likes_humans?
# => 'Nope.'

Robot.new.likes_humans?
# => 'Nope.'
Repeats

Grep through the DOM using the Capybara API

When your Cucumber feature needs to browse the page HTML, and you are not sure how to express your query as a clever CSS or XPath expression, there is another way: You can use all and find to grep through the DOM and then perform your search in plain Ruby.

Here is an example for this technique:

Then /^I should see an image with the filename...
Repeats

Understanding SQL compatibility modes in MySQL and MariaDB

MySQL and MariaDB have an SQL mode setting which changes how MySQL behaves.

The SQL mode value is comprised of multiple flags like "STRICT_TRANS_TABLES, NO_ZERO_IN_DATE". Each flag activates or disables a particular behavior.

The default SQL mode varies widly between versions of MySQL and MySQL. In general, more recent versions of MySQL and MariaDB have stricter settings than older versions, and MySQL has stricter settings than the more liberal MariaDB.

If your app explodes af…

Repeats

Detect the current Rails environment from JavaScript or CSS

Detecting if a Javascript is running under Selenium WebDriver is super-painful. It's much easier to detect the current Rails environment instead.

You might be better of checking against the name of the current Rails environment. To do this, store the environment name in a data-environment of your <body>. E.g., in your application layout:

%body{'data-environment' => Rails.env}

Now you can say in a piece of Jav…

Making httpclient use the operating system's SSL cert store

The httpclient gem comes with a custom SSL cert store.

While an customizable, application-level cert store is great when you need to deal with broken or self-signed certificates, you usually want to use the cert store from the underlying Linux. The Linux cert store is updated periodically while httpclient's cert store goes out of date and will eventually not be able to verify certs.

To use the cert store from the underlying operating system:

```ruby
client = HTTPClient.new
client.ssl_config.cert_store…

Repeats

RSpec: be_true does not actually check if a value is true

Don't use be_true to check if a value is true. It actually checks if it anything other than nil or false. That's why it has been renamed to be_truthy in recent RSpec versions.

The same thing holds for be_false, which actually checks if a value is not "truthy".

If you want to check for true or false in RSpec 2, write this instead:

value.should == true
value.should == false

If you want to check for true or false in RSpec 3+, write this instead:

```
expec…

Legacy docs for Font Awesome 4.7

See the attached link for a list of icons in Font Awesome 4.

Icon names work differently in Font Awesome 5, where a name is only valid in combination with a name of the icon set.

External contentRepeats

Installing multiple MySQL versions on the same Linux with mysql-sandbox

Ubuntu has a package mysql-sandbox that lets you install multiple MySQL versions into your user home:

sudo apt install mysql-sandbox
# Download mysql distribution .tar.gz from mysql.com
# You must choose "Generic Linux" instead of "Ubuntu" so you get a .tar.gz instead of .deb
make_sandbox mysql-5.7.21-linux-glibc2.12-x86_64.tar.gz

Note that will extract the files into the current folder and expects them to live there forever. You might want to move the file to a persistent place like bin/sandbox_dist before.

On older distr…

This website uses cookies to improve usability and analyze traffic.
Accept or learn more