On 04/08/2017 5:51 AM, frédéric Clement wrote:
Hello,
I want to use a package to load and set up a working environment (Only
intern used). It has function, but also create a connection object
(RPostgreSQL) to make dplyr::tbl implicitely use this connection.
After trying to save the connection object in "Data\"... and failed. I made
the following work around.
Is it the right way to do it, or should it be solved in other ways.
PS: This is my first attent at package development experience, I mainly
follow http://r-pkgs.had.co.nz/
regards
frederic Clement
- the script
.onAttach <- function(libname = find.package("dbName"), pkgname = "dbName")
{
packageStartupMessage("Intranet Company required")
dbNameConPool = dbName_create_pool()
assign("dbNameConPool", dbNameConPool, envir =
as.environment("package:dbName"))
}
Usually you should use .onLoad, not .onAttach. If someone who hasn't
attached your package calls one of the functions using dbName::fn(...),
your package will be loaded but not attached. Similarly if another
package imports one of your functions.
## This is a function so that I can call it in .onAttach
##
dbName_create_pool = function(){
DBI::dbConnect(drv = RPostgreSQL::PostgreSQL(),
user = "dbName",
password = .rs.askForPassword("Enter password:"),
port = ,
host = "dbName-int.company.com")
}
However, for this particular use, it might be bad to put the code even
in .onLoad. A better way to go would be to have a function in your
package that calls dbName_create_pool the first time you call it, and
just returns the same value on subsequent calls. For example,
getcon <- local({
con <- NULL
function() {
if (is.null(con))
con <<- dbName_create_pool()
con
}})
This way nobody is prompted for a password unless they actually need to
access the database.
#' Dummy function
#'
#' Only used for package build purpose
#' to import the usefull function.
#' @return NULL
#' @export
#' @import dplyr dbplyr DBI magrittr RPostgreSQL tidyr
#'
#' @examples
#' fun_import()
fun_import <- function(){
NULL
}
Not sure why you'd want these 13 lines instead of editing your NAMESPACE
file, but that's your choice...
Duncan Murdoch
--- session
R version 3.4.1 (2017-06-30)
Platform: i386-w64-mingw32/i386 (32-bit)
Running under: Windows >= 8 x64 (build 9200)
Matrix products: default
locale:
[1] LC_COLLATE=German_Germany.1252 LC_CTYPE=German_Germany.1252
LC_MONETARY=German_Germany.1252 LC_NUMERIC=C
LC_TIME=German_Germany.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
loaded via a namespace (and not attached):
[1] compiler_3.4.1 tools_3.4.1
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