Code360 powered by Coding Ninjas X Naukri.com. Code360 powered by Coding Ninjas X Naukri.com
Table of contents
1.
Introduction
2.
GraphQL
3.
Tech Stack for GraphQL
4.
Basic-level GraphQL Interview Questions
4.1.
1. What is GraphQL?
4.2.
2. List a few companies that use GraphQL.
4.3.
3. What is a query language?
4.4.
4. What are the main ideas of the GraphQL query language?
4.5.
5. Do you consider GraphQL to be a database technology?
4.6.
6. What is the response type of a GraphQL query?
4.7.
7. Name a few programming languages that can be used to build a GraphQL server.
4.8.
8. How does GraphQL aid in the data loading process?
4.9.
9. What are your thoughts on GraphiQL?
4.10.
10. What do you know about GraphQL arguments?
4.11.
11. What was the reason behind the development of GraphQL?
4.12.
12. What does 'ast' mean in GraphQL?
4.13.
13. What is the definition of an exclamation point in GraphQL?
4.14.
14. Where is GraphQL useful?
4.15.
15. What does "GraphQL schema" mean?
4.16.
16. What are the disadvantages of using GraphQL?
5.
Intermediate-level GraphQL Interview Questions
5.1.
17. What are the reasons behind using GraphQL while we already had an API named REST?
5.2.
18. Is GraphQL only for React / Javascript Developers?
5.3.
19. How to do Error Handling in GraphQL?
5.4.
20. What is GraphQL Authentication and Authorization?
5.5.
21. What is GraphQL Over-fetching?
5.6.
22. What exactly is under-fetching?
5.7.
23. How does GraphQL fix the problems of over-fetching and under-fetching data?
5.8.
24. Can GraphQL API be used to handle offline usage?
5.9.
25. What are the primary operations supported by GraphQL?
5.10.
26. Explain the primary distinction between REST and GraphQL.
5.11.
27. How can I perform multiple GraphQL changes all at once?
6.
Advanced-level GraphQL Interview Questions
6.1.
28. What are the main advantages of using GraphQL?
6.2.
29. Explain the difference between type and input type in GraphQL.
6.3.
30. How does server-side caching work in GraphQL?
6.4.
31. What is a GraphQL Fragment?
6.5.
32. In GraphQL, what is the purpose of an interface?
6.6.
33. In GraphQL, what is the union?
6.7.
34. What are Enums in GraphQL used for?
6.8.
35. What are the main operations that GraphQL supports?
6.9.
36. How do you prevent nested attack on GraphQL server?
6.10.
37. What does resolver do in GraphQL?
6.11.
38. How do you use different status codes in GraphQL responses?
6.12.
39. What factors determine when to use GraphQL instead of HATEOAS?
6.13.
40. How can you give information to fields when using GraphQL queries?
7.
Conclusion
Last Updated: Jun 12, 2024
Medium

40 Most Important GraphQL Interview Questions & Answers 2024

Author Rashi
0 upvote

Introduction

Would you like to broaden your horizons and begin a successful career as a GraphQL developer in a top MNC? If you answered yes, you've come to the right place. These GraphQL interview questions and basic GraphQL information will help you get through your primary GraphQL interview as a candidate and a recruiter.

40 Most Important GraphQL Interview Questions & Answers 2024

GraphQL

GraphQL- A query language created by Facebook in 2012 that provides a standard interface between the client and the server for data retrieval and modification. The client queries the GraphQL server for information. Client-specified inquiries are those where the answer format is specified in the query and is determined by the client instead of the server. The data structure is not hard-coded, as opposed to standard REST APIs, making the data retrieval from the server more efficient for the client. GraphQL, as database technology, needs to be more frequently understood. However, this is a common misconception. GraphQL is a query language for APIs. In that regard, it is database agnostic, meaning it can work with any database or none.

Also read about - GraphQL Requests in Ready API

Click on the following link to read further: Java OOPs Interview Questions.

Get the tech career you deserve, faster!
Connect with our expert counsellors to understand how to hack your way to success
User rating 4.7/5
1:1 doubt support
95% placement record
Akash Pal
Senior Software Engineer
326% Hike After Job Bootcamp
Himanshu Gusain
Programmer Analyst
32 LPA After Job Bootcamp
After Job
Bootcamp

Tech Stack for GraphQL

techstack for graphql

Any company that hires a GraphQL developer prefers that you should have the below-listed tech skills to be proficient in the role.

  • Familiarity with GraphQL through the Apollo Client.
     
  • Understanding of a variety of front-end languages and frameworks.
     
  • Understanding of the Java microservices ecosystem and applications.
     
  • Understanding of XML and JavaScript.

Basic-level GraphQL Interview Questions

The following are some detailed GraphQL interview questions and answers for freshers or entry-level positions.

1. What is GraphQL?

GraphQL is a query language. It is used for APIs and includes the runtime for query execution. Its development began in 2012 at Facebook. However, it was only in 2015 that it was made open source.

2. List a few companies that use GraphQL.

Many large organizations, including Github, Facebook, Pinterest, Intuit, Coursera, Shopify, DailyMotion, Yelp, and others, use GraphQL.

3. What is a query language?

A query language, in simple terms, uses queries to retrieve data from a database. GraphQL is a query language that is used to create APIs.

4. What are the main ideas of the GraphQL query language?

The main ideas of the GraphQL query language are:

  • Declarative Data Fetching: Clients specify exactly what data they need.
  • Hierarchical Structure: Queries are structured hierarchically, mirroring the shape of the response.
  • Strongly Typed System: GraphQL APIs are defined by a schema, ensuring type safety.
  • Single Endpoint: GraphQL typically exposes a single endpoint for querying and mutating data.
  • Introspection: GraphQL APIs support introspection, allowing clients to query the schema itself for discovery and documentation.

5. Do you consider GraphQL to be a database technology?

GraphQL is not a database technology. It is a query language for APIs, not a database query language. 

6. What is the response type of a GraphQL query?

GraphQL queries return JSON responses. The response is determined by the query used in the request.

7. Name a few programming languages that can be used to build a GraphQL server.

Many languages, including JavaScript, Python, Java, PHP, Haskell, Ruby, C#, Scala, Go, Elixir, Erlang, R, and Clojure, can be used to implement GraphQL servers.

8. How does GraphQL aid in the data loading process?

GraphQL can provide the client with only the information that is required. Even if the object model has a large number of fields, the client can only request the ones that are required.

9. What are your thoughts on GraphiQL?

GraphiQL is a GraphQL user interface representation. It is an in-browser IDE for exploring GraphQL and making GraphQL usage simple. GraphQL supports real-time error highlighting, allowing you to easily identify and handle errors.

10. What do you know about GraphQL arguments?

When we need to request specific data in GraphQL Queries and Fields, we use arguments.

11. What was the reason behind the development of GraphQL?

GraphQL was developed by Facebook to provide a more efficient and flexible way for apps to request and receive data from servers, addressing the limitations of REST APIs.

12. What does 'ast' mean in GraphQL?

In GraphQL, 'ast' stands for Abstract Syntax Tree. It represents the structure of a GraphQL query as a tree data structure.

13. What is the definition of an exclamation point in GraphQL?

In GraphQL, an exclamation point (!) denotes a non-nullable type. It indicates that a field or an argument cannot return a null value.

14. Where is GraphQL useful?

GraphQL is useful in scenarios where you need to fetch data from multiple sources or where you want to empower clients to request only the data they need, reducing over-fetching and under-fetching.

15. What does "GraphQL schema" mean?

"GraphQL schema" refers to the blueprint that defines the types and relationships available in a GraphQL API. It specifies how clients can query and mutate data.

16. What are the disadvantages of using GraphQL?

Disadvantages of using GraphQL include increased complexity in implementation and caching strategies, potential for overly nested queries leading to performance issues, and lack of built-in support for some features like caching and authorization. Additionally, migrating existing REST APIs to GraphQL might require significant effort.

Intermediate-level GraphQL Interview Questions

The following are some detailed intermediate-level GraphQL interview questions and answers that are frequently asked for GraphQL developer roles. 

17. What are the reasons behind using GraphQL while we already had an API named REST?

GraphQL offers advantages over REST due to its flexibility, allowing clients to request only the data they need, reducing over-fetching. It simplifies multiple requests into one, optimizing network usage. Also, it offers a strong type system for data validation, introspection for easy documentation, and real-time capabilities, improving developer productivity.

18. Is GraphQL only for React / Javascript Developers?

No, GraphQL is not exclusive to React or JavaScript developers. It's a language-agnostic technology, meaning it can be used with various programming languages. Developers in languages like Python, Ruby, Java, and more can also utilize GraphQL to build APIs and interact with data efficiently.

19. How to do Error Handling in GraphQL?

In GraphQL, error handling involves returning error information in the response. You can use GraphQL's built-in error type to include specific error messages or codes. Additionally, you can define custom error handling logic in your server code to handle exceptions and provide meaningful error messages to clients.

20. What is GraphQL Authentication and Authorization?

Authentication is the process of claiming one's identity. Authentication in GraphQL can be accomplished using common patterns such as OAuth. OAuth is an open protocol that allows secure authentication from the web, mobile, and desktop applications in a simple and standard manner.
Authorization, on the other hand, is a process used to define permission rules that describe the access rights of particular users and user groups to specific parts of the system. When implementing authorization in GraphQL, it is recommended that any data access logic be delegated to the business logic layer rather than handled directly.

21. What is GraphQL Over-fetching?

Over-fetching is when the client receives too much or extra data in response to an API request. Over-fetching results in a lot of extra data in the response you don't use. Overfetching increases the payload size unnecessarily.

22. What exactly is under-fetching?

Under-fetching is a response in which the client receives insufficient data. The under-fetching response does not have enough information with a call to an endpoint, so you must call a second endpoint or multiple API calls to complete your request.

23. How does GraphQL fix the problems of over-fetching and under-fetching data?

GraphQL solves over-fetching and under-fetching by allowing clients to request precisely the data they need. Clients specify their data requirements in queries, and servers respond with only the requested data, eliminating extra data retrieval. This customization optimizes data transfer, improving efficiency and reducing wasted resources.

24. Can GraphQL API be used to handle offline usage?

GraphQL can help with offline usage by allowing clients to request and store data locally. Clients can execute cached queries when offline, but new data requests might not work without a network connection. Implementing data synchronization and caching strategies is essential for robust offline GraphQL functionality.

25. What are the primary operations supported by GraphQL?

GraphQL supports three operation types: query, mutation, and subscription. The query used for requesting is a read operation, the mutation is used for write operations, and the subscription is used to listen for any changes to the data. If the client subscribes to that event, the server sends a notification message after data changes.

26. Explain the primary distinction between REST and GraphQL.

The primary distinction between REST and GraphQL is that GraphQL does not deal with dedicated resources; instead, everything is regarded as a graph and thus is connected and can be queried to app-specific needs.

27. How can I perform multiple GraphQL changes all at once?

To perform multiple GraphQL changes all at once, you can use a feature called "Batching" or "Batched Mutations". Batching allows you to combine multiple GraphQL operations into a single request to the server, reducing the number of network round-trips and improving efficiency.

Here's how you can perform multiple GraphQL changes all at once using batching:

  • Combine Operations: Group your GraphQL mutations or queries into a single batch request.
  • Send Batch Request: Send the batched request to the GraphQL server using your preferred HTTP client library or tool. Make sure the server endpoint supports batching.
  • Process Batch Response: Receive the response from the server, which typically contains individual responses for each operation within the batch.
  • Handle Results: Process the results of each operation in the batch response according to your application's logic.

Advanced-level GraphQL Interview Questions

The following are some detailed advanced-level GraphQL interview questions and answers that are frequently asked for GraphQL developer roles.

28. What are the main advantages of using GraphQL?

The main advantages of using GraphQL are:

  • Tailored Data Retrieval: GraphQL lets you ask for exactly the data you need, preventing the wasteful fetching of unnecessary information.
     
  • Single point: It uses a single endpoint for all requests, making it easier to manage and reducing network traffic compared to multiple endpoints in REST.
     
  • Error Prevention: GraphQL's strict structure catches errors early in development and provides clear documentation.
     
  • Real-Time Updates: It supports real-time data, which is great for chat apps and live updates.
     
  • Adaptability: GraphQL makes it easier to evolve and add features to your API without breaking existing functionality.

29. Explain the difference between type and input type in GraphQL.

  • A Type in GraphQL represents an object or a piece of data in your system, like a user, a post, or a comment. An Input Type is also a structure, but it's used when you want to send data to your server to create or update something.
     
  • Type defines the structure of the data, specifying what fields are available and what types those fields have (like text or numbers). Input Type defines the shape of the data you can send as input, including what fields are required and what types those fields should be.
     
  • Types are used to define what data can be queried (read) from your GraphQL API. Input types are used to define the format of the data that clients can send when making mutations (operations that change data) in GraphQL.

30. How does server-side caching work in GraphQL?

The difficulty in maintaining server-side caching remains a concern with GraphQL, particularly when compared to REST. Because the data format is guaranteed not to change, caching data for each endpoint is simple with REST. GraphQL, on the other hand, makes it impossible to anticipate what a client will want next; as a result, a cache layer seated behind the API makes little sense. As a result, server-side caching in GraphQL remains a challenge.

31. What is a GraphQL Fragment?

The fragment is used when a GraphQL query is extensive and consists of reusable components. You can use the reusable portion to build a fragment that you can then use in the query. The fragment concept was developed to make it easier to organize code and reduce duplication.

32. In GraphQL, what is the purpose of an interface?

An interface is used in GraphQL to list the standard fields of a GraphQL object. Other objects can also use this interface to inherit properties.

33. In GraphQL, what is the union?

In GraphQL, we must sometimes represent multiple objects, which is why the union is used. A union allows the user to specify more than one type as a return type.

34. What are Enums in GraphQL used for?

In GraphQL, an enum or enumeration type is a particular type of scalar used to declare a type, including a detailed list of allowed values.

35. What are the main operations that GraphQL supports?

GraphQL supports three main operations:

  • Query: Retrieves data from the server, allowing clients to specify exactly what information they need.
     
  • Mutation: Modifies data on the server, enabling clients to create, update, or delete data.
     
  • Subscription: Establishes real-time connections for receiving updates when data changes, ideal for live notifications and dynamic content.

36. How do you prevent nested attack on GraphQL server?

To prevent nested query attacks on a GraphQL server, you can:

  • Set depth limits: Limit the nesting depth of queries to prevent excessively complex or recursive queries.
     
  • Implement query complexity analysis: Calculate query complexity and reject queries that exceed a predefined threshold.
     
  • Use rate limiting: Restrict the number of queries a client can make within a specified time frame.

37. What does resolver do in GraphQL?

A resolver is used in GraphQL to handle queries and generate GraphQL responses.

38. How do you use different status codes in GraphQL responses?

In GraphQL responses, different status codes are typically not used in the same way as in REST APIs. Instead, GraphQL responses usually have a standard structure where errors are handled within the "errors" array of the response payload. However, HTTP status codes can still be used to indicate the overall success or failure of the request, such as using 200 for successful responses and 4xx or 5xx codes for errors at the HTTP level.

39. What factors determine when to use GraphQL instead of HATEOAS?

The factors that determine when to use GraphQL instead of HATEOAS (Hypermedia as the Engine of Application State) include the complexity of data requirements, the need for flexibility in data retrieval, and the specific use case of your application. GraphQL is well-suited for scenarios where clients require fine-grained control over the data they retrieve and need to fetch data from multiple sources efficiently. On the other hand, HATEOAS is more focused on defining how clients interact with resources through hypermedia links and is often used in RESTful architectures to support discoverability and self-descriptive APIs.

40. How can you give information to fields when using GraphQL queries?

In GraphQL queries, you can provide additional information to fields using arguments. Arguments allow you to customize the behavior of fields and filter, paginate, or transform the returned data. Arguments are specified within parentheses after the field name in the query syntax. For example, you can pass arguments like id, filter, orderBy, first, and skip to fields to specify which data you want to retrieve or how you want it to be sorted and paginated.

Conclusion

This blog has covered basic information about GraphQL and the tech stack used for GraphQL. We have covered GraphQL interview questions level-wise, that is, basic, intermediate and advanced level GraphQL Interview Questions.
Recommended Readings:

Refer to our Guided Path to upskill yourself in DSACompetitive ProgrammingJavaScriptSystem Design, and many more! If you want to test your competency in coding, you may check out the mock test series and participate in the contests hosted on Coding Ninjas Studio!

Also check out the Interview guide for Product Based Companies as well as some of the Popular interview problems from top tech companies like Amazon, Adobe, Google, Uber, Microsoft, etc.

Happy Learning!

Previous article
Top Git Interview Questions and Answers (2023)
Next article
Hibernate Interview Questions
Live masterclass