R/wpd_get_query.R

In petermeissner/wikipediadumbs: Handling Wikipedia Page View Dumps

#' wpd_get_query
#'
#' Establish a connection, execute SQL statement against database, close connection and return.
#'
#' @param query SQL statement to execute
#' @param verbose return extra information -- timings, potential database errors -- or not
#'
#' @export
#'
#' @examples
#'
#'
wpd_get_query <-
  function(query, verbose = TRUE, con = NULL, node = NULL, close = NULL, dt = TRUE){

    if ( is.null(node) ){
      node <- wpd_current_node()
    }

    # returnt type dt or not
    if(dt == TRUE){
      dt <- function(x){data.table::data.table(x)}
    } else {
      dt <- function(x){x}
    }

    # establish connection
    if( is.null(con) ){

      con <- wpd_connect(node = node)
      on.exit(DBI::dbDisconnect(con))

    } else if ( !is.null(close) && close == TRUE ){

      on.exit(DBI::dbDisconnect(con))

    } else{
      # do nothing
    }

    # execute query and get potential exception/error
    res        <- list()
    res$start  <- as.character(Sys.time())
    res$return <- dt(suppressWarnings(DBI::dbGetQuery(con, query)))
    res$end    <- as.character(Sys.time())
    res$status <- DBI::dbGetException(con)
    res$host   <- DBI::dbGetInfo(con)$host
    res$node   <- names(wpd_nodes)[wpd_nodes == res$host]

    # return
    if ( verbose == TRUE ){
      return(res)
    }else{
      return(res$return)
    }
  }