First GraphQL query - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a GraphQL query?

A GraphQL query is a request sent to a GraphQL server to ask for specific data. It lets you specify exactly what information you want.

beginner

How do you write a simple GraphQL query to get a user's name and email?

You write it like this:

{ user { name email } }

This asks for the user's name and email only.

beginner

Why is GraphQL called a 'query language'?

Because it lets you ask (query) for exactly the data you want from a server, unlike traditional APIs that send fixed data.

beginner

What does the curly braces {} mean in a GraphQL query?

Curly braces group fields you want to get. They show the shape of the data you want back.

beginner

Can a GraphQL query request multiple fields at once?

Yes! You can ask for many fields in one query by listing them inside curly braces.

What does a GraphQL query do?

A Requests specific data from a server

B Updates data on the server

C Deletes data from the server

D Creates a new database

A GraphQL query asks the server for specific data you want.

Which symbol groups fields in a GraphQL query?

A <> angle brackets

B [] brackets

C () parentheses

D {} curly braces

Curly braces {} group the fields you want in a GraphQL query.

How do you ask for a user's name and email in GraphQL?

A (user: name, email)

B { user { name email } }

C [user: name, email]

D <user>name,email</user>

The correct syntax uses curly braces to specify fields inside the user object.

Can a GraphQL query request multiple fields at once?

A Yes

B No

C Only one field per query

D Only if fields are related

GraphQL queries can request many fields together.

What is the main advantage of GraphQL queries over traditional APIs?

A They use less memory

B They are faster to write

C You get exactly the data you ask for

D They don't need a server

GraphQL lets you specify exactly what data you want, avoiding extra data.

Explain what a GraphQL query is and how it works.

Think about how you ask a friend for exactly what you want.

Write a simple GraphQL query to get a user's name and email.

Use { user { name email } } format.

Practice

1. What does a basic GraphQL query do?

easy

A. It asks for specific data by listing fields inside curly braces.

B. It updates data in the database.

C. It deletes data from the server.

D. It creates a new database schema.

Solution

1. Step 1: Understand GraphQL query purpose

   A GraphQL query is designed to request specific data from a server.

2. Step 2: Identify query syntax

   The query lists the fields wanted inside curly braces to specify what data to fetch.

3. Final Answer:

   It asks for specific data by listing fields inside curly braces. -> Option A

4. Quick Check:

   GraphQL query = request data [OK]

Hint: Remember: queries fetch data by listing fields [OK]

Common Mistakes:

• Confusing queries with mutations
• Thinking queries modify data
• Mixing query syntax with SQL

2. Which of the following is the correct syntax for a simple GraphQL query to get a user's name?

easy

A. query { user { name } }

B. query user { name }

C. { user name }

D. query user name { }

Solution

1. Step 1: Review GraphQL query structure

   A query starts with the keyword 'query' (optional), followed by curly braces enclosing the fields.

2. Step 2: Check each option's syntax

   query { user { name } } correctly uses 'query' and nested braces for user and name fields.

3. Final Answer:

   query { user { name } } -> Option A

4. Quick Check:

   Correct braces and field nesting = query { user { name } } [OK]

Hint: Use nested braces for nested fields [OK]

Common Mistakes:

• Missing curly braces
• Incorrect field nesting
• Wrong keyword placement

3. Given this GraphQL query:

query { book { title author } }

What data will the server return?

medium

A. SyntaxError: Missing fields

B. { "data": { "book": "title author" } }

C. { "book": { "title": "string", "author": "string" } }

D. { "data": { "book": { "title": "string", "author": "string" } } }

Solution

1. Step 1: Understand GraphQL response format

   GraphQL returns data inside a 'data' object matching the query structure.

2. Step 2: Match query fields to response

   The query asks for 'book' with 'title' and 'author', so response includes these nested fields.

3. Final Answer:

   { "data": { "book": { "title": "string", "author": "string" } } } -> Option D

4. Quick Check:

   Response matches query structure [OK]

Hint: Response wraps requested fields inside 'data' object [OK]

Common Mistakes:

• Omitting 'data' wrapper in response
• Returning fields as a string
• Confusing syntax error with valid query

4. Identify the error in this GraphQL query:

query { user { id name 

medium

A. Fields 'id' and 'name' are invalid.

B. Incorrect keyword 'query' used.

C. Missing closing curly braces for 'user' and 'query'.

D. Query should not have nested fields.

Solution

1. Step 1: Check query syntax completeness

   The query opens braces for 'user' and 'query' but does not close them.

2. Step 2: Confirm correct use of keywords and fields

   'query' keyword is correct; 'id' and 'name' are valid fields; nested fields are allowed.

3. Final Answer:

   Missing closing curly braces for 'user' and 'query'. -> Option C

4. Quick Check:

   Unclosed braces cause syntax error [OK]

Hint: Count opening and closing braces carefully [OK]

Common Mistakes:

• Forgetting to close all braces
• Assuming keywords are wrong
• Thinking nested fields are invalid

5. You want to fetch a list of users with their id and name using GraphQL. Which query correctly does this assuming the server has a 'users' field returning a list?

hard

A. query { users: id, name }

B. query { users { id name } }

C. query { user { id name } }

D. query users { id name }

Solution

1. Step 1: Identify the correct root field for multiple users

   The server field for multiple users is 'users', not 'user'.

2. Step 2: Check query syntax for nested fields

   query { users { id name } } correctly queries 'users' with nested 'id' and 'name' fields inside braces.

3. Final Answer:

   query { users { id name } } -> Option B

4. Quick Check:

   Correct root field and nested fields = query { users { id name } } [OK]

Hint: Use plural field for lists, nest fields inside braces [OK]

Common Mistakes:

• Using singular 'user' for list data
• Incorrect field alias syntax
• Omitting braces for nested fields