check_dbtable_variable.R

#' Check if a variable is available in a given table
#' @param error Indicates the behaviour when a variable is missing. Gives an error when error = TRUE (default). Return FALSE otherwise.
#' @inheritParams odbc_get_id
#' @export
#' @importFrom DBI dbListFields
#' @importFrom stats na.fail
#' @return TRUE when all variables are present in the table.
check_dbtable_variable <- function(
  table,
  variable,
  schema = "public",
  channel,
  error = TRUE
){
  table <- check_single_character(table, name = "table")
  variable <- check_character(
    x = variable,
    name = "variable",
    na.action = na.fail
  )
  if (length(variable) == 0) {
    stop("'variable' must contain at least one value")
  }
  check_dbtable(table = table, schema = schema, channel = channel, error = TRUE)
  # nocov start

  check <- variable %in%
    dbListFields(conn = channel$con, name = c(schema, table))
  if (all(check)) {
    return(TRUE)
  }
  if (error) {
    stop(
      "Variable(s) missing from '", table, "': ",
      paste(variable[!check], collapse = ", ")
    )
  } else {
    return(FALSE)
  }
  # nocov end
}