Enum types in GraphQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define an enum type for colors.

GraphQL

enum Color {
  RED
  GREEN
  [1]
}

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

AORANGE

BYELLOW

CBLUE

DPURPLE

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase enum values.

Adding values not related to colors.

The enum type Color includes RED, GREEN, and BLUE as valid values.

2fill in blank

medium

Complete the code to use the enum type Status in a GraphQL schema.

GraphQL

type Task {
  id: ID!
  title: String!
  status: [1]
}

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

AString

BInt

CBoolean

DStatus

Attempts:

3 left

💡 Hint

Common Mistakes

Using a scalar type like String instead of the enum type.

Forgetting to capitalize the enum type name.

The status field uses the Status enum type to restrict its values.

3fill in blank

hard

Fix the error in the enum definition by completing the missing value.

GraphQL

enum Direction {
  NORTH
  EAST
  SOUTH
  [1]
}

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AWEST

BUP

CDOWN

DLEFT

Attempts:

3 left

💡 Hint

Common Mistakes

Using directions like UP or DOWN which are not part of compass points.

Using lowercase or misspelled values.

The enum Direction should include the four main compass points: NORTH, EAST, SOUTH, and WEST.

4fill in blank

hard

Fill both blanks to define an enum and use it in a type.

GraphQL

enum Priority {
  [1]
  LOW
  MEDIUM
}

type Issue {
  id: ID!
  priority: [2]
}

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AHIGH

BPriority

CString

DURGENT

Attempts:

3 left

💡 Hint

Common Mistakes

Using a scalar type like String instead of the enum type for the field.

Adding invalid enum values.

The enum Priority includes HIGH, LOW, and MEDIUM. The priority field in Issue uses the Priority enum type.

5fill in blank

hard

Fill all three blanks to define an enum, use it in a type, and set a default value.

GraphQL

enum Role {
  [1]
  USER
  ADMIN
}

input User {
  id: ID!
  role: [2] = [3]
}

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

AGUEST

BRole

DString

Attempts:

3 left

💡 Hint

Common Mistakes

Using a scalar type like String instead of the enum type for the field.

Not setting a default value or using an invalid default.

Using lowercase enum values.

The enum Role includes GUEST, USER, and ADMIN. The role field in User uses the Role enum type with a default value of GUEST.

Practice

1. What is the main purpose of using enum types in GraphQL schemas?

easy

A. To allow any string value for a field

B. To create a numeric range for a field

C. To define a list of objects

D. To restrict a field to a fixed set of allowed values

Solution

1. Step 1: Understand enum purpose

   Enums limit a field to specific predefined values, ensuring data consistency.

2. Step 2: Compare options

   Only To restrict a field to a fixed set of allowed values describes restricting values to a fixed set, which is the enum's role.

3. Final Answer:

   To restrict a field to a fixed set of allowed values -> Option D

4. Quick Check:

   Enum = fixed allowed values [OK]

Hint: Enums fix allowed values, not free text or ranges [OK]

Common Mistakes:

• Thinking enums allow any string
• Confusing enums with lists or objects
• Assuming enums define numeric ranges

2. Which of the following is the correct syntax to define an enum type Status with values ACTIVE and INACTIVE in GraphQL?

easy

A. enum Status: ACTIVE | INACTIVE

B. enum Status { ACTIVE INACTIVE }

C. enum Status = ["ACTIVE", "INACTIVE"]

D. type Status = enum { ACTIVE, INACTIVE }

Solution

1. Step 1: Recall GraphQL enum syntax

   GraphQL enums are defined using enum Name { VALUE1 VALUE2 } syntax.

2. Step 2: Check each option

   enum Status { ACTIVE INACTIVE } matches the correct syntax. Others use invalid or mixed syntax.

3. Final Answer:

   enum Status { ACTIVE INACTIVE } -> Option B

4. Quick Check:

   Correct enum syntax = enum Status { ACTIVE INACTIVE } [OK]

Hint: Enums use curly braces with values, no equals or brackets [OK]

Common Mistakes:

• Using equals sign or brackets for enums
• Confusing enum with type or array syntax
• Using colon or pipe symbols incorrectly

3. Given the enum definition:

enum Role { ADMIN USER GUEST }

and the query:

{ userRole }

where userRole returns ADMIN, what will be the output type of userRole?

medium

A. A boolean true

B. An integer representing ADMIN

C. "ADMIN" (a string matching enum value)

D. An error because ADMIN is not a string

Solution

1. Step 1: Understand enum value representation

   GraphQL enums return the enum value as a string matching one of the defined enum names.

2. Step 2: Analyze the query output

   The query returns ADMIN, which is output as the string "ADMIN".

3. Final Answer:

   "ADMIN" (a string matching enum value) -> Option C

4. Quick Check:

   Enum output = string value [OK]

Hint: Enum values output as strings, not numbers or booleans [OK]

Common Mistakes:

• Expecting numeric or boolean output
• Thinking enum values cause errors
• Confusing enum with custom object types

4. Consider this enum definition:

enum Color { RED GREEN BLUE }

Which of the following queries will cause a validation error?

medium

A. { favoriteColor(color: YELLOW) }

B. { favoriteColor(color: GREEN) }

C. { favoriteColor(color: RED) }

D. { favoriteColor(color: BLUE) }

Solution

1. Step 1: Check enum allowed values

   The enum Color allows only RED, GREEN, and BLUE.

2. Step 2: Identify invalid value

   { favoriteColor(color: YELLOW) } uses YELLOW, which is not in the enum, causing a validation error.

3. Final Answer:

   { favoriteColor(color: YELLOW) } -> Option A

4. Quick Check:

   Invalid enum value = validation error [OK]

Hint: Only use enum values defined exactly, others cause errors [OK]

Common Mistakes:

• Using values not in enum
• Ignoring case sensitivity in enum values
• Assuming enums accept any string

5. You want to add a new enum Priority with values LOW, MEDIUM, and HIGH to a GraphQL schema. You also want to ensure that a query tasksByPriority(priority: Priority) returns only tasks matching the selected priority. Which of the following schema snippets correctly defines the enum and query?

hard

A. enum Priority { LOW MEDIUM HIGH } type Query { tasksByPriority(priority: Priority): [Task] }

B. type Priority { LOW MEDIUM HIGH } type Query { tasksByPriority(priority: Priority): [Task] }

C. enum Priority = [LOW, MEDIUM, HIGH] type Query { tasksByPriority(priority: Priority): [Task] }

D. enum Priority { LOW, MEDIUM, HIGH } type Query { tasksByPriority(priority: Priority): Task }

Solution

1. Step 1: Define enum correctly

   enum Priority { LOW MEDIUM HIGH } type Query { tasksByPriority(priority: Priority): [Task] } uses correct enum syntax without commas: enum Priority { LOW MEDIUM HIGH }.

2. Step 2: Define query returning list of tasks

   The query returns a list [Task], matching multiple tasks by priority.

3. Step 3: Check other options

   type Priority { LOW MEDIUM HIGH } type Query { tasksByPriority(priority: Priority): [Task] } wrongly defines Priority as a type, not enum. enum Priority = [LOW, MEDIUM, HIGH] type Query { tasksByPriority(priority: Priority): [Task] } uses invalid enum syntax with equals and brackets. enum Priority { LOW, MEDIUM, HIGH } type Query { tasksByPriority(priority: Priority): Task } uses commas in enum and returns a single Task, not list.

4. Final Answer:

   enum Priority { LOW MEDIUM HIGH } type Query { tasksByPriority(priority: Priority): [Task] } -> Option A

5. Quick Check:

   Correct enum + list query = enum Priority { LOW MEDIUM HIGH } type Query { tasksByPriority(priority: Priority): [Task] } [OK]

Hint: Enums use braces without commas; queries return list with [Type] [OK]

Common Mistakes:

• Using commas inside enum definitions
• Defining enum as type instead of enum
• Returning single object instead of list for multiple results