Complete hiring guide for Symfony developers

Creating a solid job ad to hiring a Symfony developer is not a breezer. It takes time and knowledge of technicalities and specifics, and that is just the start of the whole hiring process, including promoting the ad, looking for tech experts in the right places, carefully conducting a candidate selection, and scheduling interviews. And if you do all of this alone, it becomes even more challenging.

You need to consider all technical factors before you start the recruitment – professional background, expertise, education, work experience, interview questions, technical test results, and similar. Let's begin.

About Symfony

Symfony represents a recognized and stable PHP framework for web development and, at the same time, a complete set of reusable PHP components too. As a framework, it accelerates web app creation and app maintenance, and as a set of components, it offers 50 reusable, stand-alone components that reduce costs in the long run, and set a foundation for quality PHP apps.

The best way developers utilize Symfony is as a ready-to-use fullstack framework for building scalable web apps and new frameworks. The architecture of Symfony is MVC (model-view-controller), which helps to create web apps quickly, in a well-structured, layered, and logical way. With Symfony, developers easily divide software into smaller parts for easy deployment and maintenance. This framework is also popular because it makes coding simplified, offers a modular structure, easy-to-use features, smooth functionality, and open-source code.

Finding and interviewing a Symfony developer

Let's break down the recruitment practicalities and interviewing of Symfony developers with several aspects to keep in mind.

Tips for recruiters and hiring managers

The search for a good Symfony developer is successful only if you start off with a well-constructed job ad. The job ad template should have precise phrasing, the applicant should understand precisely what is required for that role, and the whole template should be as concise as possible. If you are still determining what ad structure to go with, you can easily use and edit existing job templates. Promoting the job ad on job searching platforms is quite a popular way to find and hire Symfony developers, but you can also find a tech expert in your base from before.

Let's see what the job ad needs to cover, i.e., skills and prerequisites.

Technical skills checklist

An excellent Symfony developer would ideally have extensive knowledge and experience of:

• Symfony – A Symfony developer has to know how to work with this framework by heart and build apps efficiently and quickly. They need to have at least three years of experience with this.

• PHP – There are many PHP components in Symfony, so working with PHP for at least four years in the past is another must-have prerequisite.

• Frontend technologies – An advanced knowledge of frontend technologies, such as JavaScript, HTML, and CSS, is required to communicate smoothly with other frontend developers.

• TDD (Test-Driven Development) – Using TDD is vital to produce excellent, clean code.

• OOP (Object Oriented Programming) – The OOP makes code maintenance and modifications easy. The dev can create new objects over existing ones with minimal changes.

• Git and version control – With Git and other version controls, developers increase their overall efficiency, speed up development, and track and manage code more efficiently.

• MySQL – The developer needs to work with MySQL for easier database system management, and more efficient data warehousing.

Preferred prerequisites checklist

• A degree (Bachelor) in Computer Science

• Good knowledge of Docker, and Kubernetes containerization

• Experience with other languages relevant to this role; Java, Go, C#, and Python

• Experience with React.js, but also other frameworks (Vue.js, Node.js, Angular)

• Experience with other PHP frameworks such as Laravel and Slim

• Good knowledge of cloud platforms such as AWS (e.g., Dynamo, EC2, S3, Lambda, ECS, IoT, and Cognito)

• Solid understanding of NoSQL databases such as MongoDB, Redis, Neo4J, Cosmos DB, and more.

We talked with Ben Kachoud Hicham, a Fullstack Developer at Proxify, and inquired more about what a Symfony developer must know:

“A great Symfony dev needs to be adaptable to changes and frequently follow what is new in the developers' community. They should understand the Symfony components, emphasizing Security and Form, among others. The Symfony dev should also have good experience with the design patterns, OOP, and SOLID principles. They must also master the best practices of Symfony and focus on reading the official documentation thoroughly."

Interview questions and answers

You can use the questions below for interviewing the Symfony developer and assess their knowledge based on these expected answers.

1. Can you explain the correlation between Symfony and Laravel?

Example answer: The primary connection between the two is in the database interaction. Laravel uses Eloquent (object-relational mapper - ORM) as its independent library, whereas Symfony uses Doctrine (a third-party project) for database interaction. These two have many things in common, but Laravel initially uses many Symfony components.

2. What is Symfony Controller?

Example answer: A Symfony controller represents a class method for requests' accepting and returning a Response object. The controller is accessible and viewed when mapped with the URL beforehand. Simply put, Symfony controller is a PHP function that retrieves HTTP request information and turns them into an HTTP response. This response could vary and show as XML format, 404 error, redirect, or HTML page, among others.

3. What are Symfony Annotations?

Example answer: We use annotations for information mapping (Doctrine and configuration validating). We can do this with YAML, XML, and PHP, and the benefit of annotations is easier to define within one file. For better annotations support, there are the bundles JMSSecurityExtraBundle and SensioFrameworkExtraBundle too. The latter bundle of these two is not highly recommended as part of the latest Symfony version and every annotation of this bundle is a PHP built-in attribute in symfony now.

4. Are there server requirements for Symfony installation? If yes, what are they?

Example answer: For Symfony installation, ensure you have PHP 8.1 or higher, and remember that v.8.2 is already released. Also, you need to install Install Composer too. You will also need PHP extensions (for example, Session, Ctype, PCRE, iconv, Tokenizer, and SimpleXML. Alternatively, you can install the Symfony CLI as another option, giving you a tool-filled binary for the local app running.

5. What are Symfony Bundles?

Example answer: The bundles in Symfony are folders and files organized in a specific structure. We can package the bundle specifically to an app like AdminBundle or BlogBundle. Bundles are the plugins in Symfony:

• Resources/views/Directory
• Resources/public/Directory
• Resources/config/Directory
• Dependencyinjection Directory
• Controller Directory
• Tests/Directory

After Symfony v 4.0, it is recommended that bundles are used exclusively for code sharing and sharing of features between more apps.

6. Can you explain the new bundle creation in Symfony with all its steps?

Example answer: We can create a new bundle with the following simple steps.

• For the bundle, we first need to make a new directory, in the Symfony project, under /src directory
• Then in the new directory, we make a new PHP class for the bundle. There has to be an extension from this new class to Symfony\Component\HttpKernel\Bundle\Bundle class.
• Third, it is time for bundle registration in the file app/AppKernel.php.file
• Next, the bundle's routing needs to be configured in the file app/config/routing.yml
• If we need some controller classes for the bundle now, this is the right time to create them. The same goes for any needed template files too.

7. Which directory stores Symfony logs?

Example answer: We can find all Symfony logs stored in myproject/log/directory. Per environment and application, there is just one file. The default directory structure may be customized, too (overriding the cache directory, the logs directory, the web directory, and the vendor directory)

8. What are Symfony Forms?

Example answer: Symfony Forms assists us, developers, in making and processing HTML forms, and we do this by abstracting repetitive things. With the form field helpers, we get valuable tools for rendering form content from render-all.

9. What is a Symfony default port, or how is it named?

Example answer: A default port is a web server port as a logical endpoint of connection with a network. The Symfony default port is 8000. To best use the PHP built-in web server, we need to execute server:start command: $ php bin/console server:start, which will make the server start at localhost:8000 at the Symfony app background.

10. Can you elaborate more on the Symfony Console component?

Example answer: Symfony Console component is a powerful tool that helps developers make command-line apps with its object-oriented interface. There are also 'command arguments,' input/output helpers, option parsing, and interactive dialogs. Symfony Console aims to give us a consistent and stable interface to create and run command-line apps quickly and efficiently.

11. What is the Symfony Serializer?

Example answer: Symfony Serializer is a component used for giving a specific format to objects (JSON, YAML, XML, among others). The same applies to the opposite situation when we must turn some format into an object.

12. Can you explain how you would clear the cache in Symfony?

Example answer: The best way to clear the cache is with the command cache:pool:clear, and what this does is take all the data of the storage directory and delete it. In Symfony, there are included three default clearers for this purpose:

• cache.app_clearer
• cache.global_clearer
• cache.system_clearer

13. What can you tell us about creating a custom environment intended for a Symfony app?

Example answer: This is a possible thing to do, and it is relatively simple too. First, we create a new file in app/config/directory. Then, to this, we add this code:

parameters:
env(SYMFONY_ENV): my_custom_environment

Once this is done, we can have access to the custom environment, but before we do, one last step is another command:

php app/console –env=my_custom_environment

14. Can you elaborate more on the OAuth2 authentication, and is it possible to implement this in Symfony?

Example answer: It is possible to implement the OAuth2 into Symfony. For this, we find the library FrendsOfSymfony/OAuth2-Server-Bundle and use it for adding the server functionality OAuth2 to a Symfony app.

15. Can you elaborate on the Cache component and cache adapters in Symfony?

Example answer: The Cache component gives us useful features for caching needs, from simple to complex ones. It implements the Cache Contracts (for interoperability) and PSR-6 (a caching interface). The Cache component has outstanding resilience, performance, and ready-to-use adapters applicable to many caching backends. With the Cache component, we can also enable tag-based invalidation easily. But also, through the locking and early expiration, we can easily allow cache stampede protection.

Recognizing and selecting the best Symfony developer

The great Symfony developers will have more years of experience, and they were using Symfony predominantly over anything else in their work.

Great Symfony developer candidates also perform exceptionally well on technical tests and all other interview stages. Their answers were extensive and correct, and their code was readable and clean.

Ben also added:

“A great Symfony developer will know more about this framework and answer every question they are asked. Of course, they need to be more than just advanced, and the title "expert" is something to focus on more. Also, they will know all about the framework's components in detail."

Possible challenges during the hiring of a Symfony developer

The possible challenges around hiring a Symfony developer are the common challenges that might be expected during any recruitment and hiring process.

• Lack of planning and structure – Make the recruitment organized and follow a roadmap for all stages. Have a well-assembled job ad, recognize how to shortlist the best developers of the applicant pool, and use relevant interview questions.

• Budget limitations – Make sure you allocate enough budget for the whole process; for the recruiters, (hiring) managers, and developers among the rest. Sometimes you may even have to allocate larger sums for the developer themselves, if they are in demand, have exquisite skills, and if they are also wanted by your competitors.

• Scarcity of tech experts – If all of the above happens at once, you would clearly need external help to hire a Symfony developer. Ideally, you wouldn't waste time, and you'd rely on affordable services, such as Proxify, to match you with suitable developers in just days, and to vouch for their expertise too.

The right time to use Symfony

Consider using Symfony if you need:

• To create large web apps – Symfony simplifies developers' work, saving time and money in the long run. Developers can also test much faster and more efficiently with the help of the PHPUnit Independent Library. Since Symfony consumes less memory and has built-in features for speeding up performance, it is perfect for optimizing a large workflow.

• To rely on a fast and reliable framework – With the speed Symfony offers, the developer will finish the job faster than expected. Also, Symfony works perfectly fine on various hosting solutions because of its speed. It is a convenient framework with tools for easy code corrections and fixing any security issues.

• Flexibility and adaptability for various engagements – Symfony offers good adaptability that is crucial for those constantly changing the types of engagements. Symfony will perform well with most web programs, sites, networks, and CMSs (Content Management Systems). There are standardized tools that can be useful and applied to various situations in development (such as rich libraries that will help the developer avoid repetitive tasks.

• Proper documentation – With Symfony, documentation is neatly organized, and developers can easier plan their work.

• Being part of a helpful and extensive community – It is good to know that there is always a broad community of developers who regularly update each other or offer various useful solutions.

Business benefits of using Symfony

• Saving time and money – The time-to-market is accelerated with Symfony, and the time for development gets shortened significantly through the many helpful features.

• Flexibility – There is full configuration control, compatibility with database systems, and the option to add extra functionalities too.

• Simplicity – Symfony has detailed documentation that makes using it easy through, most notably, the practical examples for creating web apps. There is also a helpful toolbar that makes it easier for developers to debug and get all needed guidelines displayed clearly. Also, automating processes is very easy, and deployment can be completed much easier as well.

• Customizability – Some notable customization features of Symfony are:

  • Micro framework for developing specific functionalities (developers can take this apart and use what’s needed separately)
  • Brick by brick for using particular features the developer requires for making a custom app with selective (but limited) functions.
  • Fullstack is a perfect option for making a multi-functional product.

• Trouble-free testing – Testing was never easier than now with the PHP Unit Independent Library. It helps stimulate HTTP requests, automates functional testing, and offers valuable tools for developers (for behavioral, unit, and functional testing).

• Total convenience – Symfony makes product development seamless and customer-centric, and developers can easily use all tools to solve security or code error issues.

• Broad community support – Developers will never run short of tools, methods, information, tips, solutions, or resources available online in the broad Symfony communities.

Ben added his point of view on the benefits he values with Symfony:

"Among the many benefits of using Symfony is the large developer community that continuously works on improving this framework and sharing useful information. Besides, with this framework, the dev can use features they need and don't need to depend on using all of them at once. Plus, the OOP is another major benefit for the work overall. Companies benefit greatly when the developers use Symfony – it's amazing how full engagements and microservices can be easily finished quickly."