<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>Db::set_append_recno()</title> <link rel="stylesheet" href="apiReference.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB C++ API Reference" /> <link rel="up" href="db.html" title="Chapter 2. The Db Handle" /> <link rel="prev" href="dbset_alloc.html" title="Db::set_alloc()" /> <link rel="next" href="dbset_bt_compare.html" title="Db::set_bt_compare()" /> </head> <body> <div xmlns="" class="navheader"> <div class="libver"> <p>Library Version 11.2.5.3</p> </div> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">Db::set_append_recno()</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="dbset_alloc.html">Prev</a> </td> <th width="60%" align="center">Chapter 2. The Db Handle </th> <td width="20%" align="right"> <a accesskey="n" href="dbset_bt_compare.html">Next</a></td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="dbset_append_recno"></a>Db::set_append_recno()</h2> </div> </div> </div> <pre class="programlisting">#include <db_cxx.h> int Db::set_append_recno(int (*db_append_recno_fcn)(DB *dbp, Dbt *data, db_recno_t recno));</pre> <p> When using the <a class="link" href="dbput.html#dbput_DB_APPEND">DB_APPEND</a> option of the <a class="xref" href="dbput.html" title="Db::put()">Db::put()</a> method, it may be useful to modify the stored data based on the generated key. If a callback function is specified using the <code class="methodname">Db::set_append_recno()</code> method, it will be called after the record number has been selected, but before the data has been stored. </p> <p> The <code class="methodname">Db::set_append_recno()</code> method configures operations performed using the specified <a class="link" href="db.html" title="Chapter 2. The Db Handle">Db</a> handle, not all operations performed on the underlying database. </p> <p> The <code class="methodname">Db::set_append_recno()</code> method may not be called after the <a class="xref" href="dbopen.html" title="Db::open()">Db::open()</a> method is called. </p> <p> The <code class="methodname">Db::set_append_recno()</code> <span> <span> method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success. </span> </span> </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Note</h3> <p> Berkeley DB is not re-entrant. Callback functions should not attempt to make library calls (for example, to release locks or close open handles). Re-entering Berkeley DB is not guaranteed to work correctly, and the results are undefined. </p> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idm1247024"></a>Parameters</h3> </div> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idm1498864"></a>db_append_recno_fcn</h4> </div> </div> </div> <p> The <span class="bold"><strong>db_append_recno_fcn</strong></span> parameter is a function to call after the record number has been selected but before the data has been stored into the database. The function takes three parameters: </p> <div class="itemizedlist"> <ul type="disc"> <li> <p> <code class="literal">dbp</code> </p> <p> The <span class="bold"><strong>dbp</strong></span> parameter is the enclosing database handle. </p> </li> <li> <p> <code class="literal">data</code> </p> <p> The <span class="bold"><strong>data</strong></span> parameter is the data <a class="link" href="dbt.html" title="Chapter 4. The Dbt Handle">Dbt</a> to be stored. </p> </li> <li> <p> <code class="literal">recno</code> </p> <p> The <span class="bold"><strong>recno</strong></span> parameter is the generated record number. </p> </li> </ul> </div> <p> The called function may modify the data <a class="link" href="dbt.html" title="Chapter 4. The Dbt Handle">Dbt</a>. If the function needs to allocate memory for the <span class="bold"><strong>data</strong></span> field, the <span class="bold"><strong>flags</strong></span> field of the returned <a class="link" href="dbt.html" title="Chapter 4. The Dbt Handle">Dbt</a> should be set to <code class="literal">DB_DBT_APPMALLOC</code>, which indicates that Berkeley DB should free the memory when it is done with it. </p> <p> The callback function must return 0 on success and <span class="bold"><strong>errno</strong></span> or a value outside of the Berkeley DB error name space on failure. </p> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idm1520560"></a>Errors</h3> </div> </div> </div> <p> The <code class="methodname">Db::set_append_recno()</code> <span> <span> method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a> exception, encapsulating one of the following non-zero errors, or return one of the following non-zero errors: </span> </span> </p> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idm144728"></a>EINVAL</h4> </div> </div> </div> <p> If the method was called after <a class="xref" href="dbopen.html" title="Db::open()">Db::open()</a> was called; or if an invalid flag value or parameter was specified. </p> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idm430632"></a>Class</h3> </div> </div> </div> <p> <a class="link" href="db.html" title="Chapter 2. The Db Handle">Db</a> </p> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idm2709832"></a>See Also</h3> </div> </div> </div> <p> <a class="xref" href="db.html#dblist" title="Database and Related Methods">Database and Related Methods</a> </p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="dbset_alloc.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="db.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="dbset_bt_compare.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">Db::set_alloc() </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> Db::set_bt_compare()</td> </tr> </table> </div> </body> </html>