How to validate uniqueness in a :has_many :through relationship with Ruby on Rails. You'll need three models in this example List, Subscriber and ListSubscriber. A list has many subscribers and a subscriber has many lists. Simple enough. Running the follo...

When you use validations in Rails, db column names are used as 'keys' for error messages. This is usually the preferred way to go about it because this maps nicely to the form fields. However, if you use a virtual attribute this may not be the case. For e...

This may not be the ideal solution. This just manages request.referers in a session variable, then looping over each unique path prints a link to the screen. It's more of a "history" than a hierarchy for resources in an application. It is however, pretty ...

Is your app connected to the internet? You can use this standalone class to check! There are no dependencies so you can copy/paste it into your project without needing to install another framework. With this class it's as simple as running `Reachabili...

Here is some very simple code to render React components dynamically without using a framework or routing library. It doesn't cover pushState and URL parsing, so in that sense it isn't a routing library. But it does let you render components from othe...