First GraphQL query - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What is the output of this GraphQL query?

Given a GraphQL schema with a Book type having fields title and author, and a query:

{ books { title author } }

What is the expected output if the data contains two books: "1984" by "George Orwell" and "Brave New World" by "Aldous Huxley"?

GraphQL

{ books { title author } }

A {"data":{"books":[{"author":"George Orwell"},{"author":"Aldous Huxley"}]}}

B {"data":{"books":[{"title":"1984"},{"title":"Brave New World"}]}}

C {"errors":[{"message":"Field 'author' not found"}]}

D {"data":{"books":[{"title":"1984","author":"George Orwell"},{"title":"Brave New World","author":"Aldous Huxley"}]}}

💡 Hint

Remember that the query requests both title and author fields for each book.

The query asks for both title and author of each book. The data contains two books with those fields, so the output includes both fields for both books.

🧠 Conceptual

intermediate

Which statement best describes a GraphQL query?

Choose the statement that correctly describes what a GraphQL query does.

A It sends a full database dump from the server to the client.

B It requests specific fields from the server, returning only the requested data.

C It updates data on the server without returning any data.

D It automatically generates a user interface based on the schema.

💡 Hint

Think about how GraphQL differs from REST in terms of data fetching.

GraphQL queries specify exactly which fields to fetch, so the server returns only that data, making data fetching efficient.

📝 Syntax

advanced

Identify the syntax error in this GraphQL query

Find the syntax error in the following GraphQL query:

{ books { title author } 

GraphQL

{ books { title author } 

A The query must start with the keyword 'query'.

B Field names must be quoted with double quotes.

C Missing closing brace '}' at the end of the query.

D The fields must be separated by commas.

💡 Hint

Check if all braces are properly closed.

The query is missing the final closing brace '}', which is required to close the query block.

❓ optimization

advanced

How to reduce data transfer in a GraphQL query?

You want to fetch only the book titles from a large list of books to reduce data transfer. Which query is best?

A { books { title } }

B { books { title author } }

C { books }

D { books { id } }

💡 Hint

Only request the fields you need.

Requesting only the title field reduces the amount of data sent compared to requesting more fields.

🔧 Debug

expert

Why does this GraphQL query return an error?

Given the schema where Book has fields title and author, why does this query return an error?

{ books { title publisher } }

GraphQL

{ books { title publisher } }

A The field 'publisher' does not exist in the 'Book' type.

B The query is missing a root operation type like 'query'.

C The field 'title' must be nested inside 'author'.

D GraphQL queries cannot request more than one field.

💡 Hint

Check if all requested fields exist in the schema.

The error occurs because 'publisher' is not defined in the 'Book' type, so the server rejects the query.