Field selection in GraphQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is field selection in GraphQL?

Field selection is the process of specifying exactly which fields you want to get back from a GraphQL query. It helps you get only the data you need.

beginner

How do you select multiple fields in a GraphQL query?

You list the fields inside curly braces after the query or object name. For example:

{ name age }

selects the name and age fields.

beginner

Why is field selection useful in GraphQL?

It reduces the amount of data sent over the network by only fetching what you need. This makes apps faster and saves bandwidth.

intermediate

Can you select nested fields in GraphQL? How?

Yes. You select nested fields by adding another set of curly braces inside a field. For example:

{ user { name email } }

gets the name and email of the user.

intermediate

What happens if you request a field that does not exist in GraphQL?

The server returns an error saying the field is unknown. GraphQL only allows fields defined in the schema to be queried.

In GraphQL, how do you specify which fields to get in a query?

A By writing JavaScript functions

B By using SQL SELECT statements

C By setting HTTP headers

D By listing fields inside curly braces after the query name

GraphQL uses curly braces to specify which fields to select in a query.

What is the benefit of selecting only needed fields in GraphQL?

A It makes the server slower

B More data is always better

C Faster responses and less data transfer

D It disables caching

Selecting only needed fields reduces data size and speeds up responses.

How do you select nested fields in GraphQL?

A By adding curly braces inside a field selection

B By using dot notation like user.name

C By writing multiple queries

D By using SQL JOINs

Nested fields are selected by adding curly braces inside the parent field.

What happens if you query a field not defined in the GraphQL schema?

A The server returns an error

B The server ignores the field

C The server returns null

D The server adds the field automatically

GraphQL servers return an error if you request unknown fields.

Which of these is a valid GraphQL field selection?

A SELECT title, author FROM books

B { title author { name } }

C <title> <author>

D GET /books/title/author

GraphQL uses curly braces to select fields and nested fields.

Explain what field selection means in GraphQL and why it is important.

Think about how you ask for only what you need in a menu.

Describe how to select nested fields in a GraphQL query with an example.

Imagine asking for details inside a bigger object.