Precise data fetching
Request only the properties a screen needs from an object.
GraphQL · Class
GraphQLField
A GraphQL field is a selectable piece of data on an object. Fields can be nested to traverse related objects, accept arguments, and be aliased in the response.
How it works
A GraphQL field represents one piece of data requested from an object. Queries begin at a root operation field and can traverse related object fields; scalar or enum fields terminate the selection, while fields returning objects require a nested selection set.
Syntax
fieldName
fieldName(argument: value)
aliasName: fieldNameReturns
A field returns the value described by its schema type; leaf fields return scalar or enum values, while object fields return nested data selected by the client.
Key points
- A field selection tells GraphQL which object data the client wants returned.
- Every operation starts from a root operation type that provides the API entry point.
- Object-valued fields can expose structured data or links to related objects.
- Nested field selections let one query move through related objects.
- An alias changes the key used for a field in the response.
Common mistakes
- A query must continue selecting fields until it reaches scalar or enum leaf values.
- Arguments are part of a field selection and can change the field's returned data.
Example: Selecting fields and related data
query {
hero {
name
friends {
name
}
}
}This query selects scalar fields directly and traverses the related friends field with its own nested selection set.
When to use it
Traversing relationships
Fetch an object and its related objects in one operation.
Comparing field results
Request multiple variants of one field using distinct arguments.
Interview questions
QWhat is a GraphQL field?
A field is a selectable piece of information on a GraphQL object. The client names the fields it wants, and the response follows that requested shape.
Follow-up: How does a client query a field that returns an object? It must add a nested selection set identifying the fields to fetch from that object.
QWhat distinguishes leaf fields from non-leaf fields?
A field that returns a scalar or enum can be selected directly as a leaf. A field returning an object represents a relationship or structured value and needs further fields selected beneath it.
Follow-up: Why are nested selections useful? They let one request traverse related objects and retrieve connected data without separate round trips.
QHow can a query customize or repeat a field?
Fields may take arguments, which alter their output. Aliases can rename response keys and allow the same field to appear more than once with different arguments.
Follow-up: How can dynamic argument values be supplied? Declare a variable in the operation and pass that variable to the field argument.
Related
QueriesSelection setsFieldsArgumentsAliasesVariablesSchemas and Types