GraphQL Fundamentals Quiz: Queries, Mutations, and Subscriptions Quiz

Challenge your understanding of GraphQL fundamentals with this quiz focused on queries, mutations, and subscriptions. Perfect for those looking to grasp core principles, request types, and real-time data handling in GraphQL.

1. Identifying Query Operations

   Which GraphQL operation type would you use to retrieve a list of user profiles from a server, such as when displaying all users on a page?

   1. Query
   2. Directive
   3. Subscription
   4. Mutation

   Explanation: The correct answer is Query because queries are used in GraphQL to request and fetch data from a server. Mutation is intended for altering data, not just retrieving it. Subscription is used for listening to real-time updates rather than fetching a list at one time. Directive is a tool for modifying query execution and is not an operation type used to retrieve data on its own.

2. Purpose of Mutations

   Suppose you are adding a new post to a blog using a GraphQL API. Which operation would be required for this action?

   1. Query
   2. Resolver
   3. Mutation
   4. Assignment

   Explanation: Mutation is the correct answer because mutations are specifically designed for writing or modifying data, such as creating a new post. Query is only for retrieving data and cannot alter the server's data. Resolver refers to a function that handles the logic for a field and is not a GraphQL operation type. Assignment is not a recognized GraphQL operation and is an incorrect term in this context.

3. Understanding Subscriptions

   When you want a client application to automatically receive updates whenever a new message is sent in a chat, what GraphQL feature would you use?

   1. Subscription
   2. Fragment
   3. Mutation
   4. Polling

   Explanation: Subscription is the correct choice because it enables clients to receive real-time data from the server as changes happen, such as new chat messages. Mutation only changes data but does not deliver updates automatically. Polling is a technique that repeatedly requests data but is less efficient and not a core GraphQL feature. Fragment is used for reusing fields within queries and does not handle real-time updates.

4. Query Syntax Basics

   Which of the following best describes the structure of a basic GraphQL query requesting a user's name and email?

   1. fetch user { name email }
   2. request { user [name; email] }
   3. getUser(name, email)
   4. query { user { name, email } }

   Explanation: The correct format is 'query { user { name, email } }' because GraphQL queries specify fields inside curly braces. The 'request' option uses incorrect syntax and brackets. 'fetch user { name email }' does not follow the standard GraphQL syntax. 'getUser(name, email)' looks like a function call and not a valid GraphQL query structure.

5. Choosing the Right Operation

   If you need to listen for updates about product inventory in real time, but you also occasionally need to update product details, which two GraphQL operation types would you use?

   1. Subscription and Query
   2. Query and Fetch
   3. Mutation and Subscription
   4. Mutation and Retrieval

   Explanation: Mutation and Subscription are the correct choices because mutation is used to update product details, and subscription keeps you informed of real-time changes like inventory updates. 'Subscription and Query' combines real-time listening and data retrieval, but would not allow changing product details. 'Query and Fetch' are both for data retrieval and do not handle updates or real-time data. 'Mutation and Retrieval' contains a non-GraphQL term, as 'Retrieval' is not an actual operation type.