<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >Trigger Functions</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REV="MADE" HREF="mailto:pgsql-docs@postgresql.org"><LINK REL="HOME" TITLE="PostgreSQL 8.0.11 Documentation" HREF="index.html"><LINK REL="UP" TITLE="PL/Python - Python Procedural Language" HREF="plpython.html"><LINK REL="PREVIOUS" TITLE="PL/Python - Python Procedural Language" HREF="plpython.html"><LINK REL="NEXT" TITLE="Database Access" HREF="plpython-database.html"><LINK REL="STYLESHEET" TYPE="text/css" HREF="stylesheet.css"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"><META NAME="creation" CONTENT="2007-02-02T03:57:22"></HEAD ><BODY CLASS="SECT1" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="5" ALIGN="center" VALIGN="bottom" >PostgreSQL 8.0.11 Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="plpython.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="plpython.html" >Fast Backward</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" >Chapter 38. PL/Python - Python Procedural Language</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="plpython.html" >Fast Forward</A ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="plpython-database.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="PLPYTHON-TRIGGER" >38.2. Trigger Functions</A ></H1 ><A NAME="AEN34451" ></A ><P > When a function is used as a trigger, the dictionary <TT CLASS="LITERAL" >TD</TT > contains trigger-related values. The trigger rows are in <TT CLASS="LITERAL" >TD["new"]</TT > and/or <TT CLASS="LITERAL" >TD["old"]</TT > depending on the trigger event. <TT CLASS="LITERAL" >TD["event"]</TT > contains the event as a string (<TT CLASS="LITERAL" >INSERT</TT >, <TT CLASS="LITERAL" >UPDATE</TT >, <TT CLASS="LITERAL" >DELETE</TT >, or <TT CLASS="LITERAL" >UNKNOWN</TT >). <TT CLASS="LITERAL" >TD["when"]</TT > contains one of <TT CLASS="LITERAL" >BEFORE</TT >, <TT CLASS="LITERAL" >AFTER</TT >, and <TT CLASS="LITERAL" >UNKNOWN</TT >. <TT CLASS="LITERAL" >TD["level"]</TT > contains one of <TT CLASS="LITERAL" >ROW</TT >, <TT CLASS="LITERAL" >STATEMENT</TT >, and <TT CLASS="LITERAL" >UNKNOWN</TT >. <TT CLASS="LITERAL" >TD["name"]</TT > contains the trigger name, and <TT CLASS="LITERAL" >TD["relid"]</TT > contains the OID of the table on which the trigger occurred. If the <TT CLASS="COMMAND" >CREATE TRIGGER</TT > command included arguments, they are available in <TT CLASS="LITERAL" >TD["args"][0]</TT > to <TT CLASS="LITERAL" >TD["args"][(<TT CLASS="REPLACEABLE" ><I >n</I ></TT >-1)]</TT >. </P ><P > If <TT CLASS="LITERAL" >TD["when"]</TT > is <TT CLASS="LITERAL" >BEFORE</TT >, you may return <TT CLASS="LITERAL" >None</TT > or <TT CLASS="LITERAL" >"OK"</TT > from the Python function to indicate the row is unmodified, <TT CLASS="LITERAL" >"SKIP"</TT > to abort the event, or <TT CLASS="LITERAL" >"MODIFY"</TT > to indicate you've modified the row. </P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="plpython.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="plpython-database.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >PL/Python - Python Procedural Language</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="plpython.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Database Access</TD ></TR ></TABLE ></DIV ></BODY ></HTML >