Type definitions in GraphQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a GraphQL type named User with an id field.

GraphQL

type User { id: [1] }

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

AString

BInt

CID!

DBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using String instead of ID for unique identifiers.

Forgetting the exclamation mark to make the field required.

The ID! type is used for unique identifiers and the exclamation mark means it is required.

2fill in blank

medium

Complete the code to add a name field of type String to the User type.

GraphQL

type User { id: ID! name: [1] }

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

AInt

BBoolean

CID

DString!

Attempts:

3 left

💡 Hint

Common Mistakes

Using ID instead of String for text fields.

Omitting the exclamation mark if the field is required.

The String! type means the name field is a required string.

3fill in blank

hard

Fix the error in the type definition by completing the field type for age.

GraphQL

type User { id: ID! age: [1] }

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

AString

BInt

CFloat

DBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using String for numeric fields.

Using Float when decimals are not needed.

The Int type is used for whole numbers like age.

4fill in blank

hard

Fill both blanks to define a Post type with title and published fields.

GraphQL

type Post { title: [1] published: [2] }

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

AString!

BBoolean!

CInt

DID

Attempts:

3 left

💡 Hint

Common Mistakes

Using Int for title instead of String.

Not marking fields as required with exclamation marks.

The title is a required string and published is a required boolean.

5fill in blank

hard

Fill all three blanks to define a Comment type with id, content, and likes fields.

GraphQL

type Comment { id: [1] content: [2] likes: [3] }

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

AID!

BString!

CInt

DBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using Boolean for likes instead of Int.

Forgetting exclamation marks for required fields.

The id is a required ID, content is required text, and likes is an integer count.

Practice

1. What is the main purpose of type definitions in GraphQL?

easy

A. To describe the shape and types of data clients can request

B. To execute database queries directly

C. To style the user interface of a GraphQL client

D. To store data permanently in the server

Solution

1. Step 1: Understand the role of type definitions

   Type definitions specify what data types exist and how data is structured in GraphQL.

2. Step 2: Identify what clients use type definitions for

   Clients use type definitions to know what data they can ask for and how it will look.

3. Final Answer:

   To describe the shape and types of data clients can request -> Option A

4. Quick Check:

   Type definitions = Describe data shape [OK]

Hint: Type definitions describe data structure, not execution or styling [OK]

Common Mistakes:

• Confusing type definitions with query execution
• Thinking type definitions style UI
• Assuming type definitions store data

2. Which of the following is the correct way to define a simple GraphQL object type named Book with a title field of type String?

easy

A. define Book { title: String }

B. object Book { title: String }

C. Book type { title: String }

D. type Book { title: String }

Solution

1. Step 1: Recall GraphQL syntax for object types

   GraphQL uses the keyword type followed by the type name and fields in braces.

2. Step 2: Match the correct syntax

   type Book { title: String } matches the correct syntax: type Book { title: String }.

3. Final Answer:

   type Book { title: String } -> Option D

4. Quick Check:

   Object type syntax = type Name { fields } [OK]

Hint: Remember: 'type' keyword defines object types in GraphQL [OK]

Common Mistakes:

• Using 'object' instead of 'type'
• Placing 'type' after the name
• Using 'define' keyword which is invalid

3. Given the following GraphQL type definition:

type User {
  id: ID!
  name: String
  age: Int
}

Which of these queries will return the name and age fields of a user?

medium

A. { user { id name age } }

B. { user { name age } }

C. { user { id } }

D. { user { age id } }

Solution

1. Step 1: Identify requested fields in each query

   We want only name and age fields returned.

2. Step 2: Check which query requests exactly those fields

   { user { name age } } requests name and age only, matching the requirement.

3. Final Answer:

   { user { name age } } -> Option B

4. Quick Check:

   Query fields = name and age only [OK]

Hint: Select only needed fields inside braces after type name [OK]

Common Mistakes:

• Including extra fields like 'id' when not asked
• Requesting fields in wrong order (order doesn't matter but distracts)
• Missing required fields if needed

4. Identify the error in this GraphQL type definition:

type Product {
  id: ID
  price: Float!
  name: String!
  description: String
  price: Int
}

medium

A. Missing exclamation mark on 'id' field

B. Incorrect type 'Float!' for price

C. Duplicate field name 'price' with different types

D. Description field cannot be optional

Solution

1. Step 1: Review all fields for correctness

   Notice that 'price' is declared twice with different types: Float! and Int.

2. Step 2: Understand GraphQL rules on field names

   Field names must be unique within a type; duplicates cause errors.

3. Final Answer:

   Duplicate field name 'price' with different types -> Option C

4. Quick Check:

   Duplicate fields cause errors [OK]

Hint: Check for repeated field names in type definitions [OK]

Common Mistakes:

• Ignoring duplicate field names
• Thinking missing '!' is always an error
• Assuming optional fields are invalid

5. You want to define a GraphQL type Order that includes an id (non-null ID), a list of items (each an Item type), and a total price (non-null Float). Which is the correct type definition?

hard

A. type Order { id: ID! items: [Item!]! total: Float! }

B. type Order { id: ID items: Item total: Float }

C. type Order { id: ID! items: [Item]! total: Float! }

D. type Order { id: ID! items: [Item!] total: Float }

Solution

1. Step 1: Analyze each field requirement

   'id' must be non-null ID, 'items' is a non-null list of non-null Item, 'total' is non-null Float.

2. Step 2: Match the correct syntax

   type Order { id: ID! items: [Item!]! total: Float! } correctly uses ID!, [Item!]! (list non-null and items non-null), and Float!.

3. Final Answer:

   type Order { id: ID! items: [Item!]! total: Float! } -> Option A

4. Quick Check:

   Non-null fields and list syntax correct [OK]

Hint: Use [Type!]! for non-null list of non-null items [OK]

Common Mistakes:

• Missing non-null markers (!)
• Using list without non-null item type
• Confusing list syntax with single type