Single endpoint architecture in GraphQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a GraphQL query field named 'user'.

GraphQL

type Query { user(id: ID!): [1] }

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

ABoolean

BString

CInt

DUser

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing a scalar type like String instead of the User type.

Using Boolean or Int which do not represent user objects.

The 'user' query returns a User type object, so the correct return type is User.

2fill in blank

medium

Complete the code to define a GraphQL mutation field named 'addUser'.

GraphQL

type Mutation { addUser(input: AddUserInput!): [1] }

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

AUser

BString

CInt

DBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Returning Boolean instead of the User object.

Returning a scalar type like String or Int.

The 'addUser' mutation returns the newly created User object.

3fill in blank

hard

Fix the error in the GraphQL schema by completing the type definition for 'Post'.

GraphQL

type Post { id: ID! title: String! author: [1] }

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

AInt

BString

CUser

DBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using String or Int instead of the User type for author.

Using Boolean which is not appropriate here.

The 'author' field should reference the User type to link the post to its author.

4fill in blank

hard

Fill both blanks to complete the GraphQL query for fetching posts with their authors.

GraphQL

query { posts { id title author { [1] [2] } } }

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

Aid

Bname

Cemail

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing email or age which may not be required.

Selecting only one field instead of both.

The author object should include id and name fields to identify the author.

5fill in blank

hard

Fill all three blanks to complete the GraphQL mutation for updating a user's email.

GraphQL

mutation { updateUser(id: [1], input: { email: [2] }) { [3] } }

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

A"123"

B"[e-mail]"

Cemail

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting quotes around string values.

Requesting the id field instead of email in the response.

Using numeric or unquoted values for id or email.

The mutation requires the user ID as a string, the new email as a string, and requests the updated email field in the response.

Practice

1. What is the main advantage of using a single endpoint architecture in GraphQL?

easy

A. It increases the complexity of client requests.

B. It requires multiple URLs for different data types.

C. It limits the flexibility of data fetching.

D. It allows all data queries to be sent to one URL.

Solution

1. Step 1: Understand the concept of single endpoint

   Single endpoint architecture means all queries go through one URL.

2. Step 2: Compare options with this concept

   Only It allows all data queries to be sent to one URL. states this clearly; others contradict the concept.

3. Final Answer:

   It allows all data queries to be sent to one URL. -> Option D

4. Quick Check:

   Single endpoint = one URL [OK]

Hint: Single endpoint means one URL for all queries [OK]

Common Mistakes:

• Thinking multiple URLs are needed
• Confusing flexibility with complexity
• Assuming single endpoint limits data fetching

2. Which of the following is the correct way to define a GraphQL endpoint URL for single endpoint architecture?

easy

A. /api/users, /api/posts

B. /data/users

C. /graphql

D. /api/v1/data

Solution

1. Step 1: Identify typical single endpoint URL

   GraphQL commonly uses a single endpoint like '/graphql' for all queries.

2. Step 2: Check other options

   Options A, C, and D suggest multiple or REST-style URLs, not single endpoint.

3. Final Answer:

   /graphql -> Option C

4. Quick Check:

   Single endpoint URL = /graphql [OK]

Hint: Single endpoint usually named '/graphql' [OK]

Common Mistakes:

• Choosing multiple URLs instead of one
• Confusing REST endpoints with GraphQL
• Ignoring standard naming conventions

3. Given the GraphQL query sent to a single endpoint /graphql:

{ user(id: "1") { name email } }

What will the server return?

medium

A. 404 Not Found

B. { "data": { "user": { "name": "Alice", "email": "[e-mail]" } } }

C. { "error": "Multiple endpoints required" }

D. { "data": { "users": [] } }

Solution

1. Step 1: Understand the query and endpoint

   The query requests user data by id from the single endpoint '/graphql'.

2. Step 2: Predict server response

   The server returns the requested user data in JSON format under 'data'. { "data": { "user": { "name": "Alice", "email": "[e-mail]" } } } matches this.

3. Final Answer:

   { "data": { "user": { "name": "Alice", "email": "[e-mail]" } } } -> Option B

4. Quick Check:

   Query returns requested user data [OK]

Hint: Single endpoint returns data in 'data' field JSON [OK]

Common Mistakes:

• Expecting HTTP 404 for valid query
• Thinking multiple endpoints needed
• Confusing error format with data response

4. A developer tries to send two different queries to separate URLs /api/users and /api/posts but gets errors. What is the likely problem in a GraphQL single endpoint setup?

medium

A. GraphQL requires all queries to go through a single endpoint URL.

B. The URLs are correct; the error is due to query syntax.

C. Multiple endpoints are allowed; the server is down.

D. The client must send queries via GET, not POST.

Solution

1. Step 1: Identify the architecture requirement

   GraphQL single endpoint architecture requires all queries to use one URL.

2. Step 2: Analyze the error cause

   Using multiple URLs breaks this rule, causing errors. GraphQL requires all queries to go through a single endpoint URL. explains this correctly.

3. Final Answer:

   GraphQL requires all queries to go through a single endpoint URL. -> Option A

4. Quick Check:

   Single endpoint means one URL [OK]

Hint: All GraphQL queries use one URL [OK]

Common Mistakes:

• Assuming multiple endpoints are allowed
• Blaming query syntax without checking URL
• Confusing HTTP methods with endpoint issues

5. How does single endpoint architecture improve backend management in a GraphQL API?

hard

A. It centralizes all data fetching through one URL, simplifying routing and security.

B. It requires separate servers for each data type, increasing complexity.

C. It forces clients to send multiple requests to different URLs.

D. It limits the types of queries clients can make.

Solution

1. Step 1: Understand backend management benefits

   Single endpoint centralizes requests, making routing and security easier to manage.

2. Step 2: Evaluate options

   It centralizes all data fetching through one URL, simplifying routing and security. correctly states this benefit; others describe drawbacks or incorrect facts.

3. Final Answer:

   It centralizes all data fetching through one URL, simplifying routing and security. -> Option A

4. Quick Check:

   Centralized endpoint = simpler backend [OK]

Hint: One URL centralizes backend tasks [OK]

Common Mistakes:

• Thinking multiple servers are needed
• Believing clients must send many requests
• Assuming query types are limited