In the 21st century, we are witnessing an era where technology reigns supreme and software development has evolved into an indispensable part of any industry. In this regard, Ruby on Rails (RoR) has emerged as a popular back-end web application framework that is highly sought after for its simplicity and speed. However, hiring a Ruby on Rails developer can be a complex process, especially if you're not familiar with the intricacies of the framework or the nuances of the development community. Therefore, I want to share 12 insights that I wish I'd been privy to before hiring a RoR developer.

Firstly, understanding the RoR community is crucial. As opposed to the mainstream software development communities (like Java or .NET) which are more structured and corporate, the RoR community is a more open, collaborative, and agile one. There is a high value placed on sharing knowledge and code. For you, as an employer, this translates into a predilection for continuous learning and adaptability in a RoR developer.

Secondly, a proficient RoR developer doesn't just know the framework, but also the language it's built on: Ruby. A strong grasp of Ruby is essential to exploit the full potential of RoR. Therefore, when hiring, emphasize on the candidate's Ruby skills.

Thirdly, RoR has a "Convention over Configuration" philosophy. This means that RoR comes with a set of conventions which help developers to streamline their work, thus reducing the time spent on mundane tasks. As an employer, it is key to find developers who are well-versed with these conventions.

Next, understanding the underlying principles of RoR is essential. The framework operates on the MVC (Model-View-Controller) design pattern. Understanding MVC is critical for a RoR developer as it directly influences how they structure and write code.

Fifthly, RoR is renowned for its testing culture. RoR developers should be familiar with Test-Driven Development (TDD) or Behavior-Driven Development (BDD), as they are a basic part of the RoR development process.

Sixthly, a good RoR developer needs to stay updated with the latest tools and techniques. RoR has a rich ecosystem of libraries, known as gems, which can significantly enhance productivity. Developers who are aware of and can leverage these resources are indeed valuable.

Seventh, proficiency in JavaScript is also a desirable trait in a RoR developer. Given that RoR is a server-side framework, skills in a client-side language like JavaScript can help create a more interactive user interface.

Eighth, remember that RoR is not a silver bullet. It has its strengths, like rapid prototyping, but it also has its weaknesses, such as scalability issues. Knowing when to use and when not to use RoR is a sign of a seasoned developer.

Ninth, the ability to work within the REST (Representational State Transfer) architecture is an important part of RoR development. A good RoR developer should be comfortable designing RESTful applications.

Tenth, a proficient RoR developer should have strong database skills. Given that RoR is often used for database-backed web applications, understanding of SQL and data modeling is essential.

Eleventh, RoR is often used in a startup environment, which requires a certain mindset. Developers need to be flexible, open to changes, and able to work under pressure.

Lastly, a deep understanding of web security is important for a RoR developer. RoR does provide several security features, but being able to identify and mitigate potential vulnerabilities is a crucial skill.

In conclusion, these insights are not exhaustive, but they provide a solid starting point when heading into the hiring process. Hiring a RoR developer is not just about their coding skills; it's also about their understanding of the framework, their attitude towards learning and collaboration, and their adaptability in a fast-paced environment. Armed with this knowledge, you can now be more discerning in your hiring process, ensuring you find the perfect fit for your project and your team.