Type definitions in GraphQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a type definition in GraphQL?

A type definition in GraphQL describes the shape of data by defining fields and their data types. It tells the server what kind of data clients can query or mutate.

beginner

What does the type keyword do in GraphQL?

The type keyword defines a new object type with a set of fields and their types. For example, type User { id: ID!, name: String } defines a User type with id and name fields.

intermediate

Explain the difference between type and input in GraphQL type definitions.

type defines the shape of data returned by queries or mutations, while input defines the shape of data sent as arguments to mutations or queries.

beginner

What does the exclamation mark ! mean in a GraphQL type definition?

The exclamation mark ! means the field is non-nullable, so it must always have a value and cannot be null.

beginner

How do you define a list of strings in a GraphQL type definition?

You define a list of strings using square brackets: [String]. For example, tags: [String] means the tags field is a list of strings.

Which keyword is used to define a new object type in GraphQL?

A type

B input

C schema

D query

The type keyword defines a new object type with fields.

What does String! mean in a GraphQL type definition?

A A non-nullable string

B An optional string

C A list of strings

D A nullable string

The exclamation mark ! means the string cannot be null.

Which type is used to define input data for mutations?

A type

B input

C enum

D scalar

input types define the shape of data sent as arguments.

How do you define a list of integers in GraphQL?

A list<Int>

B Int[]

C [Int]

D array<Int>

Lists are defined with square brackets, e.g., [Int].

What does this GraphQL type definition mean? type Book { title: String, pages: Int! }

A Both title and pages are optional

B title is required, pages is optional

C Both title and pages are required

D title is optional, pages is required

Without !, fields are nullable (optional). pages: Int! means pages is required.

Describe what a GraphQL type definition is and why it is important.

Think about how you tell a friend what information you want from them.

Explain the difference between type and input in GraphQL.

One is for output, the other for input.