EVOLUTION-MANAGER
Edit File: with_db_connection.html
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><title>R: DBMS Connections which disconnect themselves.</title> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="stylesheet" type="text/css" href="R.css" /> </head><body> <table width="100%" summary="page for with_db_connection {withr}"><tr><td>with_db_connection {withr}</td><td style="text-align: right;">R Documentation</td></tr></table> <h2>DBMS Connections which disconnect themselves.</h2> <h3>Description</h3> <p>Connections to Database Management Systems which automatically disconnect. In particular connections which are created with <code>DBI::dbConnect()</code> and closed with <code>DBI::dbDisconnect()</code>. </p> <h3>Usage</h3> <pre> with_db_connection(con, code) local_db_connection(con, .local_envir = parent.frame()) </pre> <h3>Arguments</h3> <table summary="R argblock"> <tr valign="top"><td><code>con</code></td> <td> <p>For <code>with_db_connection()</code> a named list with the connection(s) to create. For <code>local_db_connection()</code> the code to create a single connection, which is then returned.</p> </td></tr> <tr valign="top"><td><code>code</code></td> <td> <p><code>[any]</code><br /> Code to execute in the temporary environment</p> </td></tr> <tr valign="top"><td><code>.local_envir</code></td> <td> <p><code style="white-space: pre;">[environment]</code><br /> The environment to use for scoping.</p> </td></tr> </table> <h3>Value</h3> <p><code>[any]</code><br /> The results of the evaluation of the <code>code</code> argument. </p> <h3>See Also</h3> <p><code><a href="withr.html">withr</a></code> for examples </p> <h3>Examples</h3> <pre> 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) </pre> <hr /><div style="text-align: center;">[Package <em>withr</em> version 2.5.0 <a href="00Index.html">Index</a>]</div> </body></html>