Filtering

All SKG-IF search endpoints take a single required filter parameter.

Syntax

filter=key1:value1,key2:value2

Separator	Meaning	Example
:	Binds a key to its value	product_type:literature
,	AND across different keys	product_type:literature,cf.language:English
|	OR within one key's value	product_type:literature|research data

note

filter is required — a request without it fails. Values containing spaces must be URL-encoded (research%20data).

Convenience filters

Keys beginning with cf. are convenience filters: OpenAIRE extensions that are not part of the SKG-IF specification. They expose useful Graph capabilities — free-text search, subject and language filtering — that the specification does not define.

Every other key maps to a field defined by SKG-IF; for what a field means, see that entity's page in the Interoperability Framework (research product, agent, data source, grant).

Research products

GET /skg-if/v1/products

Filter	Description
product_type	One of literature, research data, research software, other (the OpenAIRE names publication, dataset, software are also accepted)
identifiers.id	Identifier value, e.g. a DOI
identifiers.scheme	Identifier scheme
contributions.by.local_identifier	Contributor by local identifier
contributions.by.identifiers.id	Contributor by identifier value, e.g. an ORCID
contributions.by.identifiers.scheme	Contributor by identifier scheme
contributions.by.given_name	Contributor given name
contributions.by.family_name	Contributor family name
contributions.by.name	Contributor full name
contributions.declared_affiliations.local_identifier	Declared affiliation by local identifier
contributions.declared_affiliations.identifiers.id	Declared affiliation by identifier value, e.g. a ROR
contributions.declared_affiliations.identifiers.scheme	Declared affiliation by identifier scheme
contributions.declared_affiliations.name	Declared affiliation name
contributions.declared_affiliations.short_name	Declared affiliation short name
funding.local_identifier	Grant by local identifier
funding.identifiers.id	Grant by identifier value
funding.identifiers.scheme	Grant by identifier scheme
cf.search.title	Free-text search in the title
cf.search.title_abstract	Free-text search in title and abstract
cf.subject	Subject / keyword
cf.language	Language, e.g. English
cf.contributions_orcid	Contributor ORCID
cf.cites	Products citing the given identifier
cf.access_rights	Access rights of the best manifestation

Organisations

GET /skg-if/v1/organisations

Filter	Description
identifiers.id	Identifier value, e.g. a ROR
name	Organisation name
short_name	Organisation short name or acronym
country	Country code, e.g. GR
cf.search.name	Free-text search across organisation names

Persons

GET /skg-if/v1/persons

Filter	Description
identifiers.id	Identifier value, e.g. an ORCID
given_name	Given name
family_name	Family name
cf.search.given_name	Free-text search in the given name
cf.search.family_name	Free-text search in the family name
cf.search.name	Free-text search across the full name

Data sources

GET /skg-if/v1/datasources

Filter	Description
data_source_classification	One of repository, aggregator, scientific database, journal archive, publisher archive, cris system
identifiers.value	Identifier value
cf.search.name	Free-text search across the official and English names

Grants

GET /skg-if/v1/grants

Filter	Description
grant_number	Grant agreement code, e.g. 101017452
acronym	Grant acronym
funding_stream	Funding stream, matched across all funding levels
funding_agency.short_name	Funder short name, e.g. EC
beneficiaries.name	Beneficiary organisation name
beneficiaries.short_name	Beneficiary organisation short name
beneficiaries.country	Beneficiary organisation country code
cf.search.title	Free-text search in the grant title
cf.duration.start.from	Start date on or after (YYYY or YYYY-MM-DD)
cf.duration.start.to	Start date on or before (YYYY or YYYY-MM-DD)
cf.duration.end.from	End date on or after (YYYY or YYYY-MM-DD)
cf.duration.end.to	End date on or before (YYYY or YYYY-MM-DD)

Errors

Code	When
422	Unknown filter key for the endpoint, malformed filter syntax, or a value outside the allowed set for product_type, data_source_classification or the grant date filters

A filter that the SKG-IF specification defines but OpenAIRE cannot serve is rejected rather than ignored, so an unsupported filter never silently returns unfiltered results:

{
  "message": "key 'identifiers.scheme' is not supported by this endpoint",
  "error": "Unprocessable Entity",
  "code": 422
}