Let's say we have posts with an attribute title that is mandatory.

Our example feature request is to tag these posts with a limited number of tags. The following chapters explain different approaches in Rails, how you can assign such a...

Slides for Henning's talk on Sep 21st 2017.

Understanding sync vs. async control flow

Talking to synchronous (or "blocking") API

print('script start')
html = get('/foo')
print(html)
print('s...

Jasmine has long standing support for writing asynchronous specs. In days gone by we used the done callback to achieve this, but these days it is possible to write much more readable specs.

Async specs

As a first example, say we want to chec...

Sometimes you might want to limit the number of associated records in a has_many association, but cannot add a foreign key to the other model (using belongs_to).

There are [many](http://stackoverflow.com/questions/8153051/rails-how-to-limit-n...

Back in the war, Rails developers had to manually HTML-escape user-supplied text before it was rendered in a view. If only a single piece of user-supplied text was rendered without prior escaping, it enabled [XSS attacks](http://en.wikipedia.org/w...

As you know, assignable_values does not invalidate a record even when an attribute value becomes unassignable. See this example about songs:

class Song < ActiveRecord::Base
  belongs_to :artist
  belongs_to :record_label

  assign...

Be careful when stubbing out attributes on records that are defined by associations. Nothing is as it seems to be.

The associated record has its own universe of things; when delegating calls to it, you ca not stub methods on the associated record...

To keep JavaScript sources small, it can sometimes make sense to split your webpack bundles. For example, if your website uses some large JavaScript library – say TinyMCE – which is only required on some selected pages, it makes sense to only load...

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, su...

Every Rails response has a default ETag header. In theory this would enable caching for multiple requests to the same resource. Unfortunately the default ETags produced b...