Resolve a Download URL via CKAN package_show — resolve_via

Queries the CKAN package_show endpoint recorded in a provenance object and returns the URL of the first resource whose name matches the provenance's name-match pattern. CKAN powers data.ontario.ca, data.gov.uk, data.gov, and most government open-data portals, so this recovers the current download URL even if the underlying resource UUID has been replaced.

Usage

resolve_via_ckan(provenance)

Arguments

provenance: A provenance list as returned by load_provenance(). Must contain dataset$ckan_api_endpoint and resource$name_match_pattern.

Value

The matched resource URL as a character string, or NULL if the endpoint is missing, the request fails, CKAN reports failure, or no resource name matches.

Examples

# Missing fields return NULL rather than erroring:
resolve_via_ckan(list())
#> NULL
# \donttest{
prov <- list(
  dataset  = list(ckan_api_endpoint = paste0(
    "https://data.ontario.ca/api/3/action/package_show",
    "?id=ontario-public-library-statistics")),
  resource = list(name_match_pattern = "2014")
)
resolve_via_ckan(prov)
#> [1] "https://files.ontario.ca/ontario_public_library_statistics_2014_open_data_csv_february_17_2016.csv"
# }