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Query the Crossref API

Source: R/crossref.R
crossref_request.Rd

  • crossref_mailto() finds the contact address that Crossref asks for;

  • crossref_request() prepares a request (not sent), to be performed sequentially or with httr2::req_perform_parallel();

  • crossref_client_limits() adapts the pace to the limits announced in the headers of a response;

  • crossref_doi_path() gives the route of a DOI;

  • crossref_search() fetches all the pages of a query.

Usage

crossref_request(
  path,
  query = list(),
  mailto = "",
  rate = 4,
  user_agent = getOption("politecollect.user_agent", "politecollect (R httr2)")
)

crossref_mailto(
  anonymous = getOption("politecollect.crossref_anonymous", FALSE)
)

crossref_client_limits(resp, rate, max_active = 1L)

crossref_doi_path(doi)

crossref_search(
  path,
  query = list(),
  mailto = crossref_mailto(),
  rows = 1000L,
  rate = 4,
  max_pages = Inf,
  on_page = NULL
)

Arguments

path

Character. Route relative to https://api.crossref.org, e.g. "journals/0002-8282/works".

query

Named list of query parameters.

mailto

Character. Contact address, also put in the user agent.

rate

Numeric. Maximum requests per second.

user_agent

Character. By default the option politecollect.user_agent, or the name of the package.

anonymous

Logical. Accept the absence of an address? For small tests: anonymous traffic is throttled harder. By default the option politecollect.crossref_anonymous, or FALSE.

resp

An httr2_response from Crossref.

max_active

Integer. Parallel requests wanted.

doi

Character vector of DOIs.

rows

Integer. Results per page (at most 1000).

max_pages

Numeric. Maximum number of pages.

on_page

Function called with each list of results and its page number, or NULL. See api_paginate().

Value

crossref_mailto(): a string. crossref_request(): an httr2_request. crossref_client_limits(): a list with rate and max_active. crossref_doi_path(): a character vector. crossref_search(): the list returned by api_paginate().

Details

The address is read from the environment variable CROSSREF_MAILTO (in ~/.Renviron). crossref_mailto() was crossref_mailto_or_abort() in building_jstor_database, where anonymous tests were switched on by the option jstor.crossref_anonymous. Its default user agent named that project; it is now the project's own politecollect.user_agent.

See also

Other APIs: api_paginate(), api_request(), ia_search(), openalex_api_key(), scopus_api_key(), sparql_query()

Examples

crossref_doi_path("10.1080/10584609.2018.1477506")
#> [1] "works/10.1080%2F10584609.2018.1477506"
if (FALSE) { # \dontrun{
res <- crossref_search(
  "journals/0002-8282/works",
  query = list(filter = "from-pub-date:2020-01"),
  mailto = crossref_mailto(), max_pages = 1
)
} # }