withr: with_db_connection – R documentation

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with_db_connection

DBMS Connections which disconnect themselves.

Description

Connections to Database Management Systems which automatically disconnect. In particular connections which are created with DBI::dbConnect() and closed with DBI::dbDisconnect().

Usage

with_db_connection(con, code)

local_db_connection(con, .local_envir = parent.frame())

Arguments

`con`	For `with_db_connection()` a named list with the connection(s) to create. For `local_db_connection()` the code to create a single connection, which is then returned.
`code`	`[any]` Code to execute in the temporary environment
`.local_envir`	`[environment]` The environment to use for scoping.

Value

[any]
The results of the evaluation of the code argument.

Examples

db <- tempfile()
with_db_connection(
  list(con = DBI::dbConnect(RSQLite::SQLite(), db)), {
    DBI::dbWriteTable(con, "mtcars", mtcars)
})

head_db_table <- function(...) {
  con <- local_db_connection(DBI::dbConnect(RSQLite::SQLite(), db))
  head(DBI::dbReadTable(con, "mtcars"), ...)
}
head_db_table()
unlink(db)

withr

Run Code 'With' Temporarily Modified Global State

v2.4.2

MIT + file LICENSE

Authors

Jim Hester [aut, cre], Kirill Müller [aut], Kevin Ushey [aut], Hadley Wickham [aut], Winston Chang [aut], Jennifer Bryan [ctb], Richard Cotton [ctb], RStudio [cph]

Initial release