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PostgreSQL 7.4.16 Documentation
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40.2. Trigger Functions

When a function is used in a trigger, the dictionary TD contains trigger-related values. The trigger rows are in TD["new"] and/or TD["old"] depending on the trigger event. TD["event"] contains the event as a string (INSERT, UPDATE, DELETE, or UNKNOWN). TD["when"] contains one of BEFORE, AFTER, and UNKNOWN. TD["level"] contains one of ROW, STATEMENT, and UNKNOWN. TD["name"] contains the trigger name, and TD["relid"] contains the OID of the table on which the trigger occurred. If the trigger was called with arguments they are available in TD["args"][0] to TD["args"][(n-1)].

If TD["when"] is BEFORE, you may return None or "OK" from the Python function to indicate the row is unmodified, "SKIP" to abort the event, or "MODIFY" to indicate you've modified the row.

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User Comments

Frankie Chow <frankie AT samba.hk>

31 Oct 2004 9:18:23

This is my trigger. I think this infomation will help some people.

-----------------------------------------------------

CREATE FUNCTION semailt() RETURNS trigger AS \'
import sys
sys.path.append(\"/var/lib/postgres/python2.1\")
import simpleemail
of = open ( \"/tmp/trigger\", \"w\")
sys.stdout = of
print \"This is the TD new:  \",
print TD[\"new\"]
print \"This is the TD old:  \",
print TD[\"old\"]
print \"This is the TD :  \",
print TD
print \"This is the TD email : \",
print TD[\"new\"][\"email\"]
TD[\"new\"][\"email\"] = simpleemail.semail(TD[\"new\"][\"email\"]).getsimple()
return \"MODIFY\"
\' LANGUAGE plpythonu;

CREATE TRIGGER semailt BEFORE INSERT OR UPDATE ON pytrigger
FOR EACH ROW EXECUTE PROCEDURE semailt();

------------------------------------------------------
--- This is my pytrigger table.

maillist=# \\d pytrigger
                           Table \"public.pytrigger\"
Column |  Type   |                         Modifiers
--------+---------+-----------------------------------------------------------
id     | integer | not null default nextval(\'public.pytrigger_id_seq\'::text)
email  | text    |
Triggers:
    semailt BEFORE INSERT OR UPDATE ON pytrigger FOR EACH ROW EXECUTE PROCEDURE semailt()

maillist=#

--- when you insert some data, you can find infomation
--- in /tmp/trigger

--------------------------------------------------------

wandell:~# cat /tmp/trigger
This is the TD new:   {\'email\': \'Frankie@Samba.HK\', \'id\': 7}
This is the TD old:   None
This is the TD :   {\'event\': \'INSERT\', \'when\': \'BEFORE\', \'args\': None, \'new\': {\'email\': \'Frankie@Samba.HK\', \'id\': 7}, \'level\': \'ROW\', \'name\': \'semailt\', \'old\': None, \'relid\': \'378878\'}
This is the TD email :  Frankie@Samba.HK
wandell:~#

-----------------------------------------------------

Thank you for pypythonu language

Frankie

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