PHP is a popular programming language that provides a strong foundation for businesses and organizations to rapidly prototype, develop and improve software for various use cases.
With over 79% of websites on the Internet using PHP, it’s clear that it’s here to stay. What PHP developers you hire will significantly impact your project’s outcome, so hiring a talented team should be a clear business priority.
In this guide, we’ll review the qualities to look for when hiring PHP developers, from critical soft skills to assessing their knowledge of the language to help you find the best programmers.
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Finding the Best PHP Developers
One of the primary aspects of hiring PHP developers is ensuring that their fundamentals are solid. Evaluate their knowledge of loops, conditionals, working with databases, and whether they have a strong foundation in Object-oriented Programming. Furthermore, adequate knowledge of popular frameworks such as Laravel and Symfony is also essential.
As your code base is constantly evolving, it’s a good idea to hire developers that know how to use the new features of PHP 8. This improves the stability and security of the code they’ll produce.
The developer should know where PHP fits in within the development stack, and as a bonus, should know how to set up, deploy and scale these applications. There should be a desire to write clean and reusable code that is well documented and tested using industry-standard tools such as PHPUnit.
A key trait of a strong developer is the willingness to learn and adapt quickly. New frameworks, extensions, features and tools are released every day, so look for developers who can pick up new tools and know where to apply them. This skill, combined with the ability to easily communicate complex solutions will help create a solid and productive team dynamic.
Now that you have an overview of what makes a PHP developer great, let’s dig into how you can evaluate these skills to find the best candidate for your project.
What Non-Technical Skills Should You Assess in a PHP Developer?
Finding someone with the right technical skills and experience is essential to creating a great development culture within your company. However, you must also consider how well they fit within the business vision, values and team.
Ensure They Have the Required Practical Skills
Some PHP developers may understand programming fundamentals and writing good code, but it’s essential to verify if they can put this into practice. Ask for examples of problems they have solved and what they would do differently. A great question to ask is:
“If you could go back in time, what advice would you give to your younger self?”
The answer to this question will allow you to see how they approach problems and if they’ve honed their skills over the years. Furthermore, pair programming sessions and working on real-world development tasks will allow them the opportunity to showcase their problem-solving ability.
It’s important to ask potential hires why they do what they do, what excites them about PHP and programming in general. For example, ask:
- “Are you passionate about users?”
- “Do you enjoy solving big problems?”
- “What’s your favorite project that you’ve worked on, and what effect did it have on the world?”
You can then follow up with questions about their ability to work in teams to understand how well they will work in your company.
Gauge Their Experience in the Field
You can’t fake experience. If you ask senior PHP developers about the newbie mistakes they’ve made during their journey, you’ll get some interesting answers. Ask candidates to share some of their highlights and the lessons learned along the way. Look for whether or not they have experience with:
- Various working environments
- Different deployment pipelines
- Technologies they had to pick up on the fly
Perhaps the developer has had to take on more responsibility than they had anticipated, for example. It could indicate that the candidate is comfortable and experienced in stepping up when necessary.
A Strong Grasp of the Entire Product Stack
PHP developers should have a firm grasp of the entire product stack, meaning they should understand how their code fits in with the markup, CSS, the database, caching and everything in between. They should understand how to deploy their code using modern version control systems and work with industry-standard tools such as Composer, PHAR, and frontend frameworks like Vue.
Look for developers who are active on platforms such as GitHub or Bitbucket, where you can see their contributions to open-source software. This information can provide a great deal of insight into their passion and experience with different frameworks and tools. It will also allow you to see how their development capabilities have matured over the years or their current level of proficiency if they’re new.
Finally, look for PHP developers that are security-minded and understand the importance of writing security-conscious code. They should understand potential exploit vectors and design their applications in ways that mitigate this.
Technical Skills to Look For in a PHP Developer
Hiring a PHP developer can be a daunting process, especially when you need to ensure they have the technical skills you require. The following are key technical skills you should consider when assessing a PHP developer’s capabilities. You can also refer to our list of sample technical interview questions as a helpful guide while evaluating your candidates.
For most development objectives, it’s incredibly important that software developers are comfortable with all aspects of Object-Oriented Programming. They should have the fundamentals of encapsulation, polymorphism, abstraction, and inheritance firmly under their belt. Equally as important is their knowledge of working with databases.
Tip: When performing a technical assessment, make sure you ask plenty of questions relating to the DBMS you use and provide them with the opportunity to answer questions related to SQL. They should know how to link their code with your database and how they can make sure that your data is protected at all times.
The PHP Ecosystem
You should also assess the PHP developers’ knowledge of the PHP ecosystem.
- Test if they are familiar with relevant documentation, working with PHP package managers, and setting up different PHP extensions.
- They should be familiar with commonly used functions within the language itself and those provided by any framework you’re using.
- They should also be familiar with building standard forms, validating inputs and handling them appropriately.
- They should be comfortable working with arrays, loops, conditionals and avoiding common inefficiencies in doing so.
Tip: As a bonus, you should also validate their knowledge of newer PHP 8 features such as traits, named attributes, union types and anonymous classes. Not only does this demonstrate essential knowledge with PHP improvements, but it also allows you to see that they know when to apply them.
Finally, it’s worth assessing whether the PHP developer is keen on working with PHP frameworks. Whatever framework they have experience in, they should be comfortable sharing the benefits these frameworks provide and why it’s better to use them for larger projects. They should understand when and where to use common programming patterns such as MVC, Builder, Factory Method, Singletons and more. These demonstrate experience and knowledge in building robust applications that will benefit your business in the long term and avoid technical debt.
Technical Interview Questions for PHP Developers
(#1) Q: What are anonymous functions?
- Functions that can only be called from inside a function
- There’s no such thing as anonymous functions in PHP
- Also known as closures, they’re functions that don’t need a name and are commonly used as arguments or being stored in variables.
- An attempt to copy the Python lambda style, that never succeeded.
(#2) Q: How important is the function `header()`?
- It’s very important as it allows the developer to add content to the header section of websites
- It’s not important and it’ll be deprecated in PHP 7.2
- It’s important because it allows the developer to append or modify data on HTTP response
- It’s important and safe to use anywhere in the code, allowing the developer to modify HTTP headers even after the data has already been sent
(#3) Q: What is a `trait`?
- It’s a structure used to compose functionality orthogonally avoiding the limitations of single inheritance and the complexity of big inheritance hierarchies
- It’s a feature in PHP 7 that allows developers to do multiple inheritance
- It’s a somewhat limited code structure that allows sharing method among multiple classes but don’t allow state and static methods for obvious reasons
- It’s a feature used to enrich interfaces and make sure the code is less error-prone
(#4) Q: Why is autoload important?
- It’s not. Autoload was a feature available in PHP 5 and it’s now deprecated in PHP 7.
- It’s important because it’s a mechanism that automatically loads PHP files whenever a class is used but not found. This makes writing OOP applications easier as the developer doesn’t need to include files in the beginning of the script every time they use a class
- It’s important because it controls how resources are used on PHP scripts as it offers memory safety to developers by loading only some bytes of files instead of the entire file which could cause memory exhaustion
- It’s important but rarely used correctly as it’s inner working is hard to understand and it’s commonly ignored by developers
(#5) Q: Regarding object comparison, it’s correct to say:
- Using the comparison operator (`==`) is the same as using the identity operator (`===`)
- By using the comparison operator (`==`) you can check if two objects contain the same values and are instances of the same class
- By using the comparison operator (`==`) you can check if two variables refer to the same instance of a given class
- By using the identity operator (`===`) you can check if a variable refers to an instance of a class which implements a specific interface or trait
To wrap up, you should have a better sense of what technical skills to look for and what key traits can provide you with insight into a candidate’s technical capability.
Feel free to use the sample questions above as a starting point to make sure they know the latest technology trends and test if they are up-to-date on PHP 8.
The PHP ecosystem is a wonderfully rich pool of knowledge and features. Knowing how to hire the very best developers with a modern understanding of how to create great web applications is paramount to finishing projects on time and developing secure, reliable, and scalable software.