Enum types in GraphQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an Enum type in GraphQL?

An Enum type in GraphQL is a special kind of scalar that restricts a field to a set of predefined constant values. It helps ensure only valid values are used.

beginner

How do you define an Enum type in GraphQL schema?

You define an Enum type using the enum keyword followed by the name and a list of allowed values inside curly braces. For example:<br>

enum Color { RED GREEN BLUE }

intermediate

Why use Enum types instead of strings in GraphQL?

Enums provide a fixed set of allowed values, which helps catch errors early, improves API clarity, and makes client-server communication more predictable compared to free-form strings.

intermediate

Can Enum types have descriptions for each value in GraphQL?

Yes, you can add descriptions to each Enum value using string comments above each value. This helps document the purpose of each option for API users.

intermediate

How does GraphQL handle invalid Enum values in queries?

If a query provides a value not defined in the Enum, GraphQL returns an error and does not execute the query, ensuring only valid Enum values are accepted.

Which keyword is used to define an Enum type in GraphQL?

A type

B interface

C scalar

D enum

The enum keyword is used to define Enum types in GraphQL.

What happens if a query uses a value not in the Enum type?

A GraphQL ignores the value

B GraphQL converts it to a string

C GraphQL returns an error

D GraphQL accepts it anyway

GraphQL returns an error if a value outside the Enum's allowed set is used.

Why are Enum types useful in GraphQL?

A They restrict values to a fixed set

B They allow any string value

C They store large text data

D They define database tables

Enums restrict values to a fixed set, improving validation and clarity.

Can Enum values have descriptions in GraphQL schema?

A No, descriptions are not allowed

B Yes, using comments above each value

C Only for the whole Enum, not values

D Only in the client code

You can add descriptions to Enum values using comments above them.

Which of these is a valid Enum definition?

A enum Status { ACTIVE INACTIVE PENDING }

B enum Status = (ACTIVE, INACTIVE, PENDING)

C type Status { ACTIVE, INACTIVE, PENDING }

D scalar Status { ACTIVE, INACTIVE, PENDING }

Option A uses the correct GraphQL Enum syntax.

Explain what an Enum type is in GraphQL and why it is useful.

Think about how you limit choices to a list of options.

Describe how to define an Enum type in a GraphQL schema with an example.

Remember the syntax starts with 'enum' followed by the name.