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Saturday, April 29, 2023

Top 21 GraphQL Interview Questions and Answers for Beginners and Experienced Developers

Hello guys, if you are preparing for web developer interviews where GraphQL skills are needed and you are looking for frequently asked GraphQL Interview questions then you have come to the right place. Earlier, I have shared both Web development interview questions as well as REST Interview Questions and in this article, I am going to share 20 common GraphQL Questions from Interviews with answers. These questions covers essential GraphQL concepts like difference between REST And GraphQL and pros and cons of using GraphQL to consume APIs. If you have used GraphQL in past then you can easily answer these questions but if you forgot then you can always join of these best GraphQL online courses to learn and revise key GraphQL concepts.

But, before we get to the GraphQL interview questions, let me tell you what it really is. GraphQL is basically a query language that is famous for giving clients exactly the data they ask for and nothing more. 

It is also perfect as a server-side runtime for application programming interfaces. GraphQL can be used for making APIs faster, efficient, flexible, as well as developer-friendly. It can also be deployed within an integrated development environment. You can use it as an alternative to REST as you can construct requests that pull data from multiple data sources in a single API call.

21 GraphQL Interview Questions with Answers for 1 to 3 Years Experienced

GraphQL also allows API maintainers the flexibility to add and depreciate fields without impacting your existing queries. This means that you can develop APIs with whatever methods you want because the GraphQL specification will make sure that they perform in predictable ways to clients.

Now let us get to the important bit. If you are looking to apply for a job that requires you to be skilled in GraphQL, you have come to the perfect place. The interview questions in this article will definitely help you land your dream software job.So what are you waiting for? Start learning now.

1. What exactly is GraphQL?

GraphQL is basically an open-source data query and manipulative language that has been developed by Facebook. It can be used for making APIs faster and more user-friendly. You can make APIs that collect data from multiple sources with a single call.

2. What do you know about the history of the GraphQL language?

Facebook initially developed GraphQL as an internal solution for the development of its mobile applications. The main reason for developing this language was to optimize REST API calls and provide an efficient alternative to REST APIs.

3. What is difference between REST and GraphQL?
While both REST and GraphQL can be used to get and post data from web service there are multiple differences between them but the the core difference between GraphQL and REST APIs is that GraphQL is a specification, a query language, while REST is an architectural concept and because of that GraphQL offers several advantage over REST. 

For example, with GraphQL you can reduce number of web service calls to the server. Suppose, if you need both Customer and Order data then instead of sending two query to customer and Order API over REST, you can just use one query to get both of these data using GraphQL. 

Here is an excellent diagram which highlights the difference between GraphQL and REST:

difference between GraphQL and REST

4. What can you tell us about authentication in GraphQL?

Authentication is basically a mechanism where you give permissions to authenticated users in your application. Using GraphQL, you can delegate the authorization using a business logic that describes whether a user has authorization for performing an action or not.

5. What are some of the features of authentication in GraphQL?

A GraphQL authentication must be able to authenticate schema at the field level. It must provide the context of the current user to the resolvers. The logic must also be hidden from the resolvers. 

6. How can you handle server-side caching in the GraphQL language?

In REST API, it is easy to implement caching as you are able to cache data for each endpoint since there is no change in data structures. But in GraphQL, the similar call is not known, and therefore it is difficult to cache. 

7. What kind of response do you get in the GraphQL language?

If you are using GraphQL, whenever a client requests something from the server, it sends back the response in the JSON format. 

GraphQL Interview Questions for 3 years experienced

8. What do you mean by over-fetching in the GraphQL language?

Over fetching is basically a condition in GraphQL where the requested client gets more data than what was requested. This will result in an increase in the payload size.  

9. What do you mean by under-fetching in the GraphQL language?

Under fetching is basically the exact opposite of over-fetching. It happens when the requested client does not get enough data and you are forced to send multiple calls to get the desired data. 
GraphQL Interview Questions with Answers

10. How can you overcome the issues of over-fetching and under-fetching in the GraphQL language?

These issues may arise due to performance issues when you have to maintain and manage multiple endpoints. You can avoid this by specifying the exact result that you need in the response from the server.

11. What are some of the advantages of using GraphQL?

GraphQL has just a single endpoint and this makes it more effective. You can also get a complex result in a single call. The speed of development is also faster in GraphQL.

12. What is the basic difference between GraphQL and REST?

The most basic difference between GraphQL and REST is the fact that while GraphQL is a language, REST is a web service API.

13. What databases can you use with GraphQL?

GraphQL can be used with both SQL as well as NoSQL databases.

GraphQL Interview Questions for 2 years experienced

14. What are some of the features of authorization in GraphQL?

A GraphQL authorization must be able to protect fields with custom rules and permissions. It must also protect part of the schema with a group of custom logic.

15. Is it possible to use GraphQL in offline mode?

This is not possible. GraphQL is designed to work in online mode. It does not have a proper standardized way of doing work in offline mode. 

16. What can you tell us about GrapiQL?

GraphQL is basically a browser-supported extension that allows you to make your use of GraphQL easier and more user-friendly. You can use it to see the errors at runtime. 

17. What are some of the major operations of GraphQL?

GraphQL mainly supports three types of operations. They are Query, Mutation, and Subscription.

18. How can you host a GraphQL server online?

For doing this, you can use a server-side programming language like Node.js or Python to create a GraphQL server as well as allow hosting on it. 

19. What advantages does GraphQL have over REST API?

Using GraphQL, you can send multiple data response formats. But you can have only one JSON format in REST API. You have consistent responses across all platforms in GraphQL. It is very hard to get consistency in REST API. You can manage the caching system in GraphQL manually whereas the caching system is automatic in REST.

GraphQL Interview Questions for 5 years experienced

20. How can you validate JSON results in the GraphQL language?

Ideally, GraphQL must return the JSON object along with a root element called data. 

21. What can you tell us about authentication in GraphQL?

In GraphQL, authentication must protect a part of the schema and not all of it. The authentication logic must be hidden from the resolvers. 

That's all about the frequently asked GraphQL Interview questions with answers for 1 to 3 years experienced. I have tried to cover as many GraphQL concepts as possible using these questions  as possible and I hope that these questions will help you to do well in your web developer interviews. If you liked this list of the Top 22 GraphQL Interview Question with Answers, feel free to share it with your friends and family. 

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Thanks for reading this article so far. All the best for your Java Backend and Fullstack Development interviews and if you have any questions which don't know answer or any doubt feel free to ask in comments.        

P. S. - If you are new to GraphQL and looking for best resources to learn both GraphQL concepts and examples then you can also checkout this list of best GraphQL courses for beginners. It contains best free courses to learn Git from Udemy, Coursera, and other popular websites. A great resource for beginners.       

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