Struct Subfield 

pub struct Subfield {

    pub id: String,
    pub display_name: Option<String>,
    pub description: Option<String>,
    pub ids: Option<HierarchyIds>,
    pub display_name_alternatives: Option<Vec<String>>,
    pub field: Option<HierarchyEntity>,
    pub domain: Option<HierarchyEntity>,
    pub topics: Option<Vec<HierarchyEntity>>,
    pub siblings: Option<Vec<HierarchyEntity>>,
    pub works_count: Option<i64>,
    pub cited_by_count: Option<i64>,
    pub works_api_url: Option<String>,
    pub updated_date: Option<String>,
    pub created_date: Option<String>,
}

A research subfield in OpenAlex’s topic hierarchy.

Subfields are the third level: domain > field > subfield > topic. There are ~252 subfields (e.g. Artificial Intelligence, Organic Chemistry).

Example

{
  "id": "https://openalex.org/subfields/1702",
  "display_name": "Artificial Intelligence",
  "field": {"id": "https://openalex.org/fields/17", "display_name": "Computer Science"},
  "domain": {"id": "https://openalex.org/domains/3", "display_name": "Physical Sciences"},
  "topics": [{"id": "https://openalex.org/T10028", "display_name": "Topic Modeling"}, ...],
  "works_count": 9059921
}

ID formats

Subfields use numeric IDs (e.g. 1702 for Artificial Intelligence).

Note

Subfields do support autocomplete (unlike domains and fields). However, the autocomplete response returns entity_type: null and short_id: "Nones/..." — these are known API quirks.

Fields

id: String

OpenAlex ID URI (e.g. "https://openalex.org/subfields/1702").

display_name: Option<String>

Human-readable subfield name (e.g. "Artificial Intelligence").

description: Option<String>

Brief description of the subfield’s scope.

ids: Option<HierarchyIds>

External identifiers (OpenAlex, Wikidata, Wikipedia).

display_name_alternatives: Option<Vec<String>>

Alternative names or name variants.

field: Option<HierarchyEntity>

The parent field this subfield belongs to.

domain: Option<HierarchyEntity>

The parent domain this subfield belongs to (grandparent in hierarchy).

topics: Option<Vec<HierarchyEntity>>

Research topics within this subfield.

siblings: Option<Vec<HierarchyEntity>>

Other subfields at the same level in the hierarchy.

works_count: Option<i64>

Total number of works in this subfield.

cited_by_count: Option<i64>

Total number of citations received by works in this subfield.

works_api_url: Option<String>

API URL to retrieve works in this subfield.

updated_date: Option<String>

ISO 8601 timestamp of the last update to this record.

created_date: Option<String>

ISO 8601 date when this record was first created.

Trait Implementations

impl Clone for Subfield

fn clone(&self) -> Subfield

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Subfield

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Subfield

fn deserialize<__D>( __deserializer: __D, ) -> Result<Subfield, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl From<Subfield> for SubfieldSummary

fn from(s: Subfield) -> Self

Converts to this type from the input type.

impl Serialize for Subfield

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.