Carrierwave reminder: always call model.save! after uploader.recreate_versions!
If your Carrierwave uploader dynamically generates the filename (e.g. by incorporating a user's name), you must call model.save! after recreating versions, because uploader.recreate_versions! does not update the model with the stored filename.
How to organize monkey patches in Ruby on Rails projects
As your Rails project grows, you will accumulate a number of small patches. These will usually fix a bug in a gem, or add a method to core classes.
Instead of putting many files into config/initializers, I recommend to group them by gem in lib/ext:
```text
lib/
ext/
factory_girl/
mixin.rb
carrierwave/
change_storage.rb
fix_cache_ids.rb
sanitize_filename_characters.rb
ruby/
range/
covers_range.rb
array/
dump_to_excel.rb
xss_aware_join.rb
enumerable/
…
How to explain SQL statements via ActiveRecord
ActiveRecord offers an explain method similar to using EXPLAIN SQL statements on the database.
However, this approach will explain all queries for the given scope which may include joins or includes.
Output will resemble your database's EXPLAIN style. For example, it looks like this on MySQL:
User.where(id: 1).includes(:articles).explain
```
EXPLAIN for: SELECT users.* FROM users WHERE users.id = 1
+—-+————-+——-+——-+—————+
| id | select_type | table | type | possible_keys |
+—-+—–…
Consul 1.0 released
We've released consul 1.0.0, which is mostly identical to 0.14.1.
The support for the following methods was dropped:
Power.for_record(record) # instead use Power.for_model(record.class)
Power#for_record(record) # instead use Power#for_model(record.class)
Power#name_for_record(record) # instead use Power#name_for_model(record.class)
How to iterate over an Enumerable, returning the first truthy result of a block ("map-find")
Ruby has Enumerable.find(&block), which returns the first item in the collection for which the block evaluates to true.
first_post_with_image = posts.find do |post|
post.image
end
However, sometimes it's not the item you're interested in, but some value depening on it – e.g. the value the block evaluated to. You could first map the collection and then take the first truthy value, but this way you need to process the whole collection twice:
first_image_url = posts.map(&:image).find(&:present?).url
If the mapping …
Simple database lock for MySQL
Note: For PostgreSQL you should use an alternative that doesn't require a database table. For MySQL we still recommend the solution in this card.
If you need to synchronize multiple rails processes, you need some shared resource that can be used as a mutex. One option is to simply use your existing (MySQL) database.
The attached code provides a database-based mutex for MySQL. You use it by simply calling
Lock....
Copy to clipboard without flash (clipboard.js)
We used zeroclipboard.js in some of our projects but now we switched to clipboard.js because it does not rely on flash. Flash support of the major browsers has ended.
Some more advantages of clipboard.js:
- it consists only of a single javascript file, so it does not trigger additional requests with rails
- it automagically provides user feedback by selecting the text it has copied
- it provides callbacks for success and error which make it easier to add custom behaviour after copying to the clipboar…
Updated: Rails routes: Extracting collection actions into their own controllers
In modern Rails versions we can define nested resources in a collection { ... } block to namespace them into an existing resource:
resources :projects, only: :show do
collection do
resource :report, only: :show, controller: 'projects/report'
end
end
This generates the following routes:
GET /projects/:id => ProjectsController#show
GET /projects/report => Projects::ReportsController#show
Note how /projects/report does not take a :project_id.
Thanks Jakob for the hint.
Cheat Sheet for the modern DOM API
See the attached link for a useful overview of modern (and classic) DOM API methods, like matches, contains, append, cssText, etc.
You will still need to look up some documentation, e.g. on how to modify a ClassList, but it's still better than browsing interfaces and superclasses of Element on MDN without knowing what to look for.
When coming from jQuery, also see the card on JavaScript without jQuery.
Why Using the Greedy .* in Regular Expressions Is Almost Never What You Actually Want – Marius Schulz
Explains the difference betwen .* and .*?, and why the latter can lead to faster patterns.
Things you probably didn’t know you could do with Chrome’s Developer Console
Collection of useful tools in the Chrome JavaScript console.
- Make the whole page editable
- This is not special to Chrome, but still a clever thing:
document.body.contentEditable=true - Taking time
- You can easily measure the time on the console with named timers:
console.time('myTime'); // Start timer console.timeEnd('myTime'); // End timer and print the time - Reference previously inspected elements (from the Elements panel)
- Variables
$0,$1, …$nreference the nth-last inspected Element.$0is the…
Make your Rails console (and irb) output better readable
Pour color on your Rails console with awesome_print. Turn confusing long strings into formatted output. Have objects and classes laid out clearly whenever you need it.
Put gem 'awesome_print', :group => :development into your Gemfile. Now on the Rails console you have the command ap that will give you a colored, formatted output of whatever you pass it. See the example output of the User class below.
For customization visit the repository on Github.
![awesome_print.png](https://makan…
AngularJS 1: How to keep "ng-hidden" elements from flickering on page load
When you have an element you want to hide, you can add a ng-show='isOpen' attribute to that element. When you set isOpen to false on the scope, the element will be hidden.
However, when you load the page, the element is usually rendered by the browser before Angular has loaded and had a chance to hide it.
Generic fix (prefer)
The ng-cloak directive was designed for exactly this purpose. Add a ng-cloak attribute or class (and more, see the link) to any element you want to …
Rails 4 introduced collection_check_boxes
Starting from Rails 4.0, you can use a special form options helper called #collection_check_boxes. It behaves similar to #collection_select, but instead of a single select field it renders a checkbox and a label for each item in the collection.
= form_for @post do |form|
= form.collection_check_boxes :author_ids, Author.all, :id, :name_with_initial
How generated form params look like ———————————…
Unpoly 0.60.0 released: No jQuery required
You may browse a formatted and hyperlinked version of this file at https://unpoly.com/changes.
0.60.0
This is a major update with some breaking changes.
Highlights
- jQuery is no longer required! Unpoly now has zero dependencies.
- New
up.elementhelpers to complement nativeElementmethods. You might not even miss jQuery anymore. - Vastly improved performance on slow devices.
- Utility functions that work with arrays and array-like values have been greatly improved.
- …