Mutation syntax in GraphQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start a GraphQL mutation operation.

GraphQL

mutation [1] { createUser(name: "Alice") { id } }

Drag options to blanks, or click blank then click option'

Aquery

BCreateUser

Cmutation

Dsubscription

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'query' instead of a mutation operation name.

Omitting the operation name entirely.

The name after mutation is the operation name. It can be any valid identifier like CreateUser.

2fill in blank

medium

Complete the code to specify the mutation field to update a user's email.

GraphQL

mutation UpdateEmail { [1](id: "123", email: "[e-mail]") { id email } }

Drag options to blanks, or click blank then click option'

AupdateUserEmail

BgetUser

CdeleteUser

DcreateUser

Attempts:

3 left

💡 Hint

Common Mistakes

Using a query field like 'getUser' in a mutation.

Using 'deleteUser' or 'createUser' instead of updating.

The mutation field updateUserEmail is used to update the user's email.

3fill in blank

hard

Fix the error in the mutation by completing the missing keyword.

GraphQL

mutation CreateUser { createUser(name: "Bob") [1] id name }

Drag options to blanks, or click blank then click option'

Aselect

Breturn

C{

Dfields

Attempts:

3 left

💡 Hint

Common Mistakes

Using keywords like 'return' or 'select' which are not part of GraphQL syntax.

Omitting the curly braces around the fields.

The selection set of fields must be enclosed in curly braces { } after the mutation field.

4fill in blank

hard

Complete the code to complete the mutation that deletes a user and returns their id and name.

GraphQL

mutation DeleteUser [1](id: "456") { id name }

Drag options to blanks, or click blank then click option'

AdeleteUser

BcreateUser

C{

D}

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'createUser' instead of 'deleteUser'.

Omitting the opening curly brace for the selection set.

The mutation field is deleteUser and the selection set starts with a curly brace {.

5fill in blank

hard

Fill both blanks to complete the mutation that creates a user and returns their id and email.

GraphQL

mutation {BLANK_1}} { {{BLANK_2}}(name: "Eve", email: "[e-mail]") { id email }

Drag options to blanks, or click blank then click option'

ACreateUser

BcreateUser

C{

DupdateUser

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'updateUser' instead of 'createUser' for creating a user.

Omitting the opening curly brace for the selection set.

The operation name is CreateUser, the mutation field is createUser, and the selection set starts with {.

Practice

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

easy

A. To define the data schema

B. To fetch data without changing anything

C. To create a new GraphQL server

D. To change data on the server like adding, updating, or deleting records

Solution

1. Step 1: Understand GraphQL operations

   GraphQL has queries to fetch data and mutations to change data.

2. Step 2: Identify mutation role

   Mutations are used to add, update, or delete data on the server.

3. Final Answer:

   To change data on the server like adding, updating, or deleting records -> Option D

4. Quick Check:

   Mutation = change data [OK]

Hint: Mutations always modify data, queries only read data [OK]

Common Mistakes:

• Confusing mutations with queries
• Thinking mutations define schema
• Assuming mutations create servers

2. Which of the following is the correct basic syntax to start a mutation in GraphQL?

easy

A. mutation { addUser(name: "Alice") { id name } }

B. query { addUser(name: "Alice") { id name } }

C. mutation addUser { name: "Alice" }

D. addUser mutation { name: "Alice" }

Solution

1. Step 1: Recognize mutation keyword usage

   Mutations start with the keyword mutation followed by braces containing the mutation call.

2. Step 2: Check correct structure

   mutation { addUser(name: "Alice") { id name } } correctly uses mutation { addUser(...) { ... } } syntax.

3. Final Answer:

   mutation { addUser(name: "Alice") { id name } } -> Option A

4. Quick Check:

   Mutation starts with 'mutation' keyword and braces [OK]

Hint: Mutation always starts with 'mutation' keyword and braces [OK]

Common Mistakes:

• Using 'query' instead of 'mutation'
• Placing mutation name before 'mutation' keyword
• Missing braces around mutation call

3. Given the mutation below, what will be returned?

mutation {
  createPost(title: "Hello") {
    id
    title
  }
}

medium

A. No return data because no fields requested

B. { "data": { "createPost": null } }

C. { "data": { "createPost": { "id": 1, "title": "Hello" } } }

D. Syntax error: missing fields

Solution

1. Step 1: Analyze mutation call and requested fields

   The mutation calls createPost with title "Hello" and requests id and title fields back.

2. Step 2: Understand expected return

   The server returns the new post's id and title as requested.

3. Final Answer:

   { "data": { "createPost": { "id": 1, "title": "Hello" } } } -> Option C

4. Quick Check:

   Requested fields returned in data [OK]

Hint: Requested fields inside mutation braces are returned [OK]

Common Mistakes:

• Expecting no return data
• Confusing syntax error with correct syntax
• Ignoring requested fields in response

4. Identify the error in this mutation:

mutation {
  updateUser(id: 5, name: "Bob")
}

medium

A. Missing requested return fields after mutation call

B. Wrong keyword, should be 'query' instead of 'mutation'

C. Mutation name 'updateUser' is invalid

D. Extra parentheses around arguments

Solution

1. Step 1: Check mutation syntax

   Mutation calls must specify which fields to return inside braces after the call.

2. Step 2: Identify missing return fields

   This mutation lacks braces with requested fields after updateUser, causing syntax error.

3. Final Answer:

   Missing requested return fields after mutation call -> Option A

4. Quick Check:

   Mutations must request return fields [OK]

Hint: Always request fields after mutation call in braces [OK]

Common Mistakes:

• Omitting return fields
• Using 'query' keyword for mutations
• Misplacing parentheses

5. You want to delete a user by ID and get back the deleted user's name and email. Which mutation is correct?

hard

A. mutation deleteUser(id: 10) { name email }

B. mutation { deleteUser(id: 10) { name email } }

C. mutation { deleteUser(id: 10) }

D. deleteUser mutation { id: 10, name, email }

Solution

1. Step 1: Confirm mutation keyword and structure

   Mutation must start with mutation keyword followed by braces containing the mutation call.

2. Step 2: Check mutation call and requested fields

   mutation { deleteUser(id: 10) { name email } } correctly calls deleteUser with id: 10 and requests name and email fields.

3. Final Answer:

   mutation { deleteUser(id: 10) { name email } } -> Option B

4. Quick Check:

   Correct mutation syntax with requested return fields [OK]

Hint: Mutation call inside braces with requested fields in nested braces [OK]

Common Mistakes:

• Placing mutation name after keyword incorrectly
• Not requesting return fields
• Using wrong keyword order