Abstract type resolution in GraphQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is abstract type resolution in GraphQL?

It is the process of determining the concrete object type that implements an abstract type like an interface or union during query execution.

beginner

Name two GraphQL abstract types that require resolution.

Interfaces and unions are the two abstract types that need resolution to find the actual object type at runtime.

intermediate

How does GraphQL resolve an abstract type?

GraphQL calls a resolveType function or uses a default mechanism to identify the concrete type of the object returned.

intermediate

Why is abstract type resolution important in GraphQL?

It allows clients to query fields specific to the concrete type while using a common interface or union, enabling flexible and type-safe queries.

advanced

What happens if GraphQL cannot resolve the concrete type of an abstract type?

The query will fail with an error because GraphQL needs to know the exact type to return the correct fields.

Which GraphQL types require abstract type resolution?

A Directive and Scalar

B Scalar and Enum

C Object and Input

D Interface and Union

Only Interface and Union types are abstract and require resolution to a concrete object type.

What function is commonly used to resolve an abstract type in GraphQL?

A resolveObject

B resolveType

C resolveQuery

D resolveField

The resolveType function is used to determine the concrete type of an abstract type.

If a GraphQL query requests fields from an interface, what must happen during execution?

A The interface is ignored and fields are returned as null

B The query is converted to a union type

C The concrete type implementing the interface must be identified

D The query fails immediately

GraphQL must identify the concrete type to return the correct fields for the interface.

What is the result if abstract type resolution fails in GraphQL?

A The query returns an error

B The query returns empty data

C The query returns default scalar values

D The query returns all possible fields

Failure to resolve the concrete type causes the query to error out.

Which of the following is NOT an abstract type in GraphQL?

A Object

B Interface

C Union

D Abstract

Object types are concrete, not abstract. Interface and Union are abstract types.

Explain how GraphQL resolves an abstract type during query execution.

Think about how GraphQL knows which actual type to use when you query an interface or union.

Why is abstract type resolution necessary in GraphQL schemas?

Consider how clients can query different types through a common abstract type.