R/helper.R

In tgraf0/wortschatzR: Wrappers Around the REST API from the Leipzig Corpora Collection

# This file contains helper functions used by other functions of the package

#' Helper function which catches (404) errors, when requesting a JSON from a remote source
#'
#' @param txt String: URL to the JSON file
#' @param quietly If FALSE, a warning message is returned, whenever an error is encountered. Default: TRUE
#'
#' @return A list with the query results and the potential error message

catch_error_json <- function(txt, quietly = TRUE){
    safe_json <- purrr::safely(jsonlite::fromJSON)
    query_result <- safe_json(txt)
        if (!quietly & !is.null(query_result$error)) warning("An error occured during the query. Most likely the api request did not yield a result (404)")
    return(query_result)
    }

#' List the available corpora of Leipzig Corpora Collection
#'
#' @param name_only logical. If TRUE, only the names of the corpora will be return.
#'
#' @return Either a tibble with all the corpora and their description or a character vector with all corpora names
#' @export
#'
#' @examples
#' list_available_corpora()
#' list_available_corpora(TRUE)

list_available_corpora <- function(name_only = FALSE){
    assertthat::assert_that(assertthat::is.flag(name_only))
    available_corpora <- jsonlite::fromJSON("http://api.corpora.uni-leipzig.de/ws/corpora/availableCorpora")
    if (name_only == TRUE){
        dplyr::pull(available_corpora, "corpusName")
    } else {
        tibble::as.tibble(available_corpora)
    }

}