How to make changes to a Ruby gem (as a Rails developer)
At makandra, we've built a few gems over the years. Some of these are quite popular: spreewald (475k downloads), active_type (330k downloads), and geordi (210k downloads) for example (numbers from 2018).
Developing a Ruby gem is different from developing Rails applications, with the biggest difference: there is no Rails. This means:
- no defined structure (neither for code nor directories)
- no autoloading of classes, i.e. you need to
requireall files yourself - no [
active_support](https://api.rubyonrails.org/classes/ActiveSupport.ht…
HTML forms with multiple submit buttons
Most forms have a single submit button that will save the record when pressed.
Sometimes a form needs additional submit buttons like "accept" or "reject". Such buttons usually attempt a state transition while updating the record.
To process a form with multiple buttons, your server-side code will need to know which button was pressed. To do so you can give each submit button a different [formaction] attribute. This will override the …
Trigger native mouse events with Javascript
The attached Coffeescript helper will let you create mouse events:
$element = $('div')
Trigger.mouseover($element)
Trigger.mouseenter($element)
Trigger.mousedown($element)
Trigger.mouseup($element)
Trigger.mouseout($element)
Trigger.mouseleave($element)
Trigger.click($element)
The dispatched events are real DOM events, which will trigger both native and jQuery handlers.
jQuery's .trigger is simpler, but will only trigger event handlers that were bound by jQuery's .on.
Real user actions t…
Do not use transparent PNGs for iOS favicons
Safari on iOS accepts an apple-touch-icon favicon that is used for stuff like desktop bookmarks. Always define a solid background color for them.
If you use PNGs with a transparent background, Safari will use just set a black background on your pretty icon. This is almost never what you want.
You can fix that by applying a white background via ImageMagick like this:
convert a...
Devise: Invalidating all sessions for a user
Background information about session storage in Rails
Rails has a default mechanism to store the session in the CookieStore. This is a cookie which holds the entire user session hash in the browser. This cookie is serialized, encoded with base64, and signed.
How Devise handles authentication
Devise uses this CookieStore. To track a users session, a salt is stored in the session cookie when a user logs in.
When a user logs out this CookieStore is overwrit…
Designing HTML email
The 90s are calling: they want their tables back. Unfortunately, you'll need them all for laying out your HTML emails. (It is really that bad.)
Email client HTML rendering is way more scattered than browser HTML. While you might have a pretty good understanding of what features and patterns you can use to support all major browsers, I doubt anyone masters this craft for HTML email clients.
The only way to ensure your email looks good (acceptable, at least) in all mail clients, is to check it. Litmus is your go-to solu…
Tasks, microtasks, queues and schedules - JakeArchibald.com
The way that Javascript schedules timeouts and promise callbacks is more complicated than you think. This can be the reason why callbacks are not executed in the order that they are queued.
Please read this article!
This is an extract of the example in the article which demonstrates the execution order of tasks and microtasks.
```
console.log('script start');
setTimeout(function() {
console.log('setTimeout');
}, 0);
Promise.resolve().then(function() {
console.log('promise1');
}).then(function() {
console.log('promise2');
});
…
CSS: Using interaction media detection to disable hover styles for devices that have no hover
Since late 2015, all major browsers (still excluding Firefox) support pointing device media queries. These can be used to distinguish e.g. coarse from fine pointers (e.g. finger vs mouse), or a device with hover support from one without (e.g. desktop with mouse vs tablet).
Motivation
When hover styles modify the DOM, most mobile devices activate the hover styles on first tap. A second tap is required to trigger a click. While this can be handy, at times it makes the UX worse.
Another issue with hover styles is that they tend to st…
Logic in media queries
Here is how to model basic logic in media queries.
AND
With keyword and.
# Target viewport widths between 500 and 800px
@media (min-width: 500px) and (max-width: 800px)
OR
Comma-separated.
# Target viewport widths below 500 or above 800px
@media (max-width: 500px), (min-width: 800px)
NOT
Needs a little overhead with not all and.
# Target devices that can't hover
@media not all and (hover)
See CSS: Using interaction media detection on why you'd need this.
Find an ActiveRecord by any column (useful for Cucumber steps)
The attached patch lets you find a record by a string or number in any column:
User.find_by_anything('carla')
User.find_by_anything('email@domain.de')
User.find_by_anything(10023)
There's also a bang variant that raises ActiveRecord::NotFound if no record matches the given value:
User.find_by_anything!('carla')
Boolean and binary columns are excluded from the search because that would be crazy.
I recommend copying the attachment to features/support/find_by_anything.rb, since it is most useful in Cucumber step …
How to make your application assets cachable in Rails
Note: Modern Rails has two build pipelines, the asset pipeline (or "Sprockets") and Webpacker. The principles below apply for both, but the examples shown are for Sprockets.
Every page in your application uses many assets, such as images, javascripts and stylesheets. Without your intervention, the browser will request these assets again and again on every request. There is no magic in Rails that gives you automatic caching for assets. In fact, if you haven't been paying attention to this, your application is probabl…
Printing background color of elements
Browsers' printing methods usually don't print background colors. In most cases this is the desired behavior, because you don't want to spent tons of ink printing the background of a web page. But in some cases you want to print the background color of elements, e.g. bars of a chart. For those elements you need to set the following css styles:
Chrome and Safari:
-webkit-print-color-adjust: exact;
Firefox:
color-adjust: exact;
Stretching an HTML page to full height
This card existed before, but was outdated due to browser implementation changes. The information below is validated for the current list of browsers we support.
By default your html and body elements are only as high as the actual page content. If you only have two lines of text in your page, your html and body elements will only be around 40 pixels high, regardless of the size of your browser window.
You might be surprised by this, since setting a background on either html and body does cover the enti…