tw_query.R

#' Perform simple Wikidata queries
#'
#' This function aims to facilitate only the most basic type of queries: return which items have the following property pairs. For more details on Wikidata queries, consult: https://www.wikidata.org/wiki/Wikidata:SPARQL_query_service/queries/examples. For complex queries, use `WikidataQueryServiceR::query_wikidata()`.
#'
#' Consider `tw_get_all_with_p()` if you want to get all items with a given property, irrespective of the value.
#'
#' @param query A list of named vectors, or a data frame (see example and readme).
#' @param fields A character vector of Wikidata fields. Ignored if `return_as_tw_search` is set to TRUE (as per default). Defaults to `("item", "itemLabel", "itemDescription")`
#' @param language Defaults to language set with `tw_set_language()`; if not set, "en". If more than one, can be set in order of preference, e.g. `c("it", "fr", "en")`. Use "all_available" to keep all languages. For available language values, see https://www.wikidata.org/wiki/Help:Wikimedia_language_codes/lists/all
#' @param return_as_tw_search Logical, defaults to TRUE. If TRUE, returns a data frame with three columns (id, label, and description) that can be piped to other `tw_` functions. If FALSE, a data frame with as many columns as fields.
#'
#' @return A data frame
#' @export
#'
#' @examples
#'
#' if (interactive()) {
#'   query <- list(
#'     c(p = "P106", q = "Q1397808"),
#'     c(p = "P21", q = "Q6581072")
#'   )
#'   tw_query(query)
#' }
tw_query <- function(query,
                     fields = c("item", "itemLabel", "itemDescription"),
                     language = tidywikidatar::tw_get_language(),
                     return_as_tw_search = TRUE) {
  if (is.data.frame(query) == FALSE) {
    query_df <- dplyr::bind_rows(query)
  } else {
    query_df <- query
  }

  query_t <- query_df %>%
    glue::glue_data("wdt:{p} wd:{q}") %>%
    stringr::str_c(collapse = ";\n")

  sparql_t <- glue::glue(
    "SELECT
             {stringr::str_c(\"?\", stringr::str_c(fields, collapse = \" ?\"))}
             WHERE{{?item {query_t} .
             SERVICE wikibase:label {{ bd:serviceParam wikibase:language '{stringr::str_c(language, collapse = ',')},[AUTO_LANGUAGE]' . }}
             }}"
  )

  response <- WikidataQueryServiceR::query_wikidata(
    sparql_query = sparql_t,
    format = "simple"
  )

  if (return_as_tw_search == TRUE) {
    response %>%
      dplyr::transmute(
        id = stringr::str_extract(.data$item,
          pattern = "Q[[:digit:]]+$"
        ),
        label = .data$itemLabel,
        description = .data$itemDescription
      )
  } else {
    tibble::as_tibble(response)
  }
}