Args argument in GraphQL - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What is the output of this GraphQL query with args?

Given the schema where books query accepts an argument author to filter books by author name, what will be the result of this query?

{ books(author: "Alice") { title author } }

GraphQL

query { books(author: "Alice") { title author } }

A [{"title": "GraphQL Basics", "author": "Alice"}, {"title": "Advanced GraphQL", "author": "Bob"}]

B [{"title": "Advanced GraphQL", "author": "Bob"}]

C []

D [{"title": "GraphQL Basics", "author": "Alice"}, {"title": "Advanced GraphQL", "author": "Alice"}]

💡 Hint

Think about how the argument filters the list of books by author.

The argument author: "Alice" filters the books to only those written by Alice. So only books with author Alice appear in the result.

📝 Syntax

intermediate

Which option correctly uses args in a GraphQL query?

Choose the valid GraphQL query syntax that passes an argument id with value 5 to the user query.

A query { user(id: 5) { name email } }

B query { user { id: 5, name, email } }

C query { user(id = 5) { name email } }

D query { user(id => 5) { name email } }

💡 Hint

Remember the syntax for passing arguments uses parentheses and colon.

Option A correctly uses parentheses and colon to pass argument id: 5. Options C and D use invalid operators. Option A tries to assign inside selection set which is invalid.

🧠 Conceptual

advanced

How do args improve GraphQL queries?

Which statement best explains the role of arguments (args) in GraphQL queries?

A Args define the schema structure and types for the GraphQL server.

B Args allow clients to specify parameters to filter or customize the data returned by a query.

C Args are used to authenticate users before running queries.

D Args automatically cache query results on the client side.

💡 Hint

Think about how you can ask for specific data using arguments.

Arguments let clients pass parameters to queries or mutations to control what data is returned or how it is processed. They do not define schema or handle authentication directly.

🔧 Debug

advanced

Why does this GraphQL query with args cause an error?

Consider this query:

query { product(id: "abc123") { name price } }

The server returns an error: Argument "id" has invalid value "abc123". What is the most likely cause?

A The argument <code>id</code> expects an integer, but a string was provided.

B The argument <code>id</code> is missing from the query.

C The field <code>product</code> does not accept any arguments.

D The query is missing a required <code>price</code> argument.

💡 Hint

Check the expected type of the argument in the schema.

The error indicates the value type is wrong. If id expects an integer, passing a string causes this error.

❓ optimization

expert

How can args optimize data fetching in GraphQL?

You want to fetch only active users from a large database. Which use of args best optimizes the query?

A query { users(filter: {active: true}) { id name } }

B query { users { id name status } }

C query { users(status: "active") { id name } }

D query { users { id name } }

💡 Hint

Consider which query reduces data transferred and server load by filtering early.

Option C uses an argument to filter users on the server side, returning only active users. Option C fetches all users with status, increasing data size. Option C fetches all users without filtering. Option C uses a filter argument but may not be supported or less standard.

Practice

1. What is the main purpose of args in a GraphQL query or mutation?

easy

A. To format the output data

B. To define the schema types

C. To connect to the database

D. To pass extra information to customize the query or mutation

Solution

1. Step 1: Understand what args do in GraphQL

   Args are used to send extra details or parameters to queries or mutations to specify what data you want.

2. Step 2: Compare with other options

   Defining schema types, formatting output, or connecting to the database are not the role of args.

3. Final Answer:

   To pass extra information to customize the query or mutation -> Option D

4. Quick Check:

   Args = extra info for queries/mutations [OK]

Hint: Args always go inside parentheses after field name [OK]

Common Mistakes:

• Thinking args define schema types
• Confusing args with output formatting
• Assuming args connect to the database

2. Which of the following is the correct syntax to pass an argument named id with value 5 to a GraphQL query field user?

easy

A. user(id: 5)

B. user[id=5]

C. user{id=5}

D. user(id=5)

Solution

1. Step 1: Recall GraphQL argument syntax

   Arguments are passed inside parentheses with colon separating name and value, like fieldName(argName: value).

2. Step 2: Check each option

   user(id: 5) uses parentheses and colon correctly. The options using brackets or braces are incorrect. user(id=5) uses equals sign which is invalid in GraphQL.

3. Final Answer:

   user(id: 5) -> Option A

4. Quick Check:

   Args syntax = parentheses + colon [OK]

Hint: Use parentheses and colon for args: field(arg: value) [OK]

Common Mistakes:

• Using brackets [] instead of parentheses ()
• Using equals sign = instead of colon :
• Using braces {} for arguments

3. Given the GraphQL query:

{ user(id: 3) { name age } }

What will be the result if the user with id=3 has name "Alice" and age 30?

medium

A. { "data": { "user": { "id": 3, "name": "Alice" } } }

B. { "data": { "user": { "name": "Alice", "age": 30 } } }

C. { "data": { "user": { "name": "Alice" } } }

D. { "error": "User not found" }

Solution

1. Step 1: Understand the query fields

   The query requests the user with id 3 and asks for the fields name and age.

2. Step 2: Match the expected output

   The response should include both name and age for user 3. { "data": { "user": { "name": "Alice", "age": 30 } } } matches this exactly. { "data": { "user": { "id": 3, "name": "Alice" } } } includes id which was not requested. { "data": { "user": { "name": "Alice" } } } misses age. { "error": "User not found" } is an error which is incorrect since user exists.

3. Final Answer:

   { "data": { "user": { "name": "Alice", "age": 30 } } } -> Option B

4. Quick Check:

   Requested fields = name, age; output matches [OK]

Hint: Output matches requested fields exactly [OK]

Common Mistakes:

• Expecting unrequested fields in output
• Ignoring requested fields in output
• Assuming error when user exists

4. Identify the error in this GraphQL query:

{ product(id=10) { name price } }

medium

A. Using equals sign (=) instead of colon (:) for argument

B. Missing curly braces around the query

C. Field name 'product' is invalid

D. Arguments must be outside parentheses

Solution

1. Step 1: Check argument syntax

   GraphQL requires arguments to use colon (:), not equals sign (=). The query uses id=10 which is invalid.

2. Step 2: Verify other parts

   The query has curly braces, 'product' is a valid field name, and arguments must be inside parentheses, so other options are incorrect.

3. Final Answer:

   Using equals sign (=) instead of colon (:) for argument -> Option A

4. Quick Check:

   Args use colon, not equals [OK]

Hint: Args use colon (:), never equals (=) [OK]

Common Mistakes:

• Using = instead of : in args
• Thinking args go outside parentheses
• Assuming missing braces error

5. You want to fetch a list of books published after year 2000 using a GraphQL query with an argument publishedAfter. Which query correctly uses the args to achieve this?

hard

A. { books["publishedAfter": 2000] { title author } }

B. { books { title author publishedAfter: 2000 } }

C. { books(publishedAfter: 2000) { title author } }

D. { books(publishedAfter = 2000) { title author } }

Solution

1. Step 1: Understand how to pass args in GraphQL

   Arguments must be inside parentheses after the field name, using colon to assign values.

2. Step 2: Evaluate each option

   { books(publishedAfter: 2000) { title author } } correctly uses parentheses and colon. { books { title author publishedAfter: 2000 } } places argument inside selection set which is invalid. { books(publishedAfter = 2000) { title author } } uses equals sign instead of colon. { books["publishedAfter": 2000] { title author } } uses brackets and quotes incorrectly.

3. Final Answer:

   { books(publishedAfter: 2000) { title author } } -> Option C

4. Quick Check:

   Args inside parentheses with colon [OK]

Hint: Args go inside parentheses with colon [OK]

Common Mistakes:

• Placing args inside selection set
• Using equals sign instead of colon
• Using brackets instead of parentheses