R/JDBCUpdateResult.R

In hoesler/dbj: Provides access to databases through the JDBC interface

#' @include JDBCResult.R
#' @include java_utils.R
NULL

#' JDBCUpdateResult class
#' 
#' The class created as a result of a database \code{\link[=dbSendQuery,JDBCConnection,character-method]{query}}
#' which returns no results (e.g. for INSERT or UPDATE statements).
#'
#' @family result classes
#' @export
JDBCUpdateResult <- setClass("JDBCUpdateResult",
  contains = c("JDBCResult"),
  slots = c(
    statement = "character",
    update_count = "numeric",
    connection = "JDBCConnection")
)

#' @describeIn JDBCUpdateResult Returns an empty data frame.
#'
#' @param res an \code{\linkS4class{JDBCUpdateResult}} object.
#' @param n optional maximum number of records to retrieve per fetch. Use \code{-1} to 
#'    retrieve all pending records; use \code{0} for to fetch the default 
#'    number of rows as defined in \code{\link{JDBC}}
#' @param ... Ignored. Needed for compatibility with generic.
#' @export
setMethod("dbFetch", signature(res = "JDBCUpdateResult", n = "numeric"),
  function(res, n, ...) {
    data.frame()
  }
)

#' @describeIn JDBCUpdateResult Returns an empty data frame.
#' @export
setMethod("dbFetch", signature(res = "JDBCUpdateResult", n = "missing"),
  function(res, n, ...) {
    data.frame()
  }
)

#' @describeIn JDBCUpdateResult Has no effect. Returns always \code{TRUE}.
#' @export
setMethod("dbClearResult", signature(res = "JDBCUpdateResult"),
  function(res, ...) {
    invisible(TRUE)
  }
)

#' @describeIn JDBCUpdateResult Unsupported
#' @export
setMethod("dbColumnInfo", signature(res = "JDBCUpdateResult"),
  function(res, ...) {
    stop("dbColumnInfo is unsupported in JDBCUpdateResult")    
  }
)

#' @describeIn JDBCUpdateResult Unsupported
#' @export
setMethod("dbGetRowCount", signature(res = "JDBCUpdateResult"),
  function(res, ...) {
    0
  }
)

#' @describeIn JDBCUpdateResult Get info
#' @export
setMethod("dbGetInfo", signature(dbObj = "JDBCUpdateResult"),
  function(dbObj, ...) {
    default_list <- callNextMethod(dbObj, ...)
    supplements <- list(
      is.select = FALSE
    )
    c(default_list, supplements)
  }
)

#' @describeIn JDBCUpdateResult Is always \code{TRUE}.
#' @export
setMethod("dbIsValid", signature(dbObj = "JDBCUpdateResult"),
  function(dbObj, ...) {
    TRUE
  }
)

#' @rdname JDBCUpdateResult-class
#' @param dbObj An object of class \code{\linkS4class{JDBCUpdateResult}}
#' @export
#' @keywords internal
setMethod("dbGetDriver", signature(dbObj = "JDBCUpdateResult"),
  function(dbObj, ...) {
    dbGetDriver(dbObj@connection) # forward
  }
)

#' @rdname JDBCUpdateResult-class
#' @section Methods:
#' \code{dbHasCompleted}: Check if all results have been fetched
#' @export
setMethod("dbHasCompleted", signature(res = "JDBCUpdateResult"),
  function(res, ...) {
    TRUE
  }
)

#' @rdname JDBCUpdateResult-class
#' @section Methods:
#' \code{dbGetStatement}: Returns the statement that was passed to dbSendQuery
#' @export
setMethod("dbGetStatement", signature(res = "JDBCUpdateResult"),
  function(res, ...) {
    res@statement
  }
)

#' @rdname JDBCUpdateResult-class
#' @section Methods:
#' \code{dbGetRowsAffected}: Returns the number of rows that were added, deleted, or updated
#' @export
setMethod("dbGetRowsAffected", signature(res = "JDBCUpdateResult"),
  function(res, ...) {
    res@update_count
  }
)