R/download_fisbroker_wfs.R

In EcoDynIZW/d6geodata: geo data acces package ecodyn department IZW

#' Download data from fisbroker
#' @param link the url of the data from fisbroker.
#' @return A folder with the data as a geopackage.
#' @export
#' @examples
#' \dontrun{
#' download_fisbroker_wfs()
#' }

#### Function
download_fisbroker_wfs <- function(link){ # a data frame is required, with at least a column for the year of data creation and WFS-link

  base_fun <- function(single_row){ # function, to be applied on each row of input table

    single_link <- single_row # WFS-link; in case, please change column

    wfs_client  <- ows4R::WFSClient$new(single_link, serviceVersion = "2.0.0")

    layer       <- wfs_client$ # layer name (incl. prefix, e. g.: "fis:")
      getCapabilities()$
      getFeatureTypes() %>%
      purrr::map_chr(function(x){x$getName()})

    if(length(layer) > 1) stop(paste0("This function is not suited for WFS-sets with multiple layers. First layer here: ", layer[1]))

    typename <- unlist(strsplit(layer, ":"))[2] # layer name without prefix

    title    <- wfs_client$ # layer title in German
      getCapabilities()$
      findFeatureTypeByName(layer)$
      getTitle()

    crs      <- wfs_client$ # CRS
      getCapabilities()$
      findFeatureTypeByName(layer)$
      getDefaultCRS()[1]$input

    link2       <- httr::parse_url(single_link)
    link2$query <- list(service   = "wfs",
                        version   = "2.0.0",
                        request   = "GetFeature",
                        typenames = typename,
                        srsName   = paste0("EPSG:", unlist(strsplit(crs, ":"))[2])) # applies CRS to shapefile for download
    request     <- httr::build_url(link2)
    request2    <- sf::st_read(request)

    return(request2)

  }

  safely_function <- purrr::safely(base_fun) # skip and save errors, when using this function
  execution       <- safely_function(link) # applies function on every row of input table
  return(execution$result)
}