Hi All,

I've changed the check_primary_key() function code to allow for either
the "automatic insert key rule" or "dependent insert key rule".
Previously it restricted the addtion of a child entry if the
corresponding parent entry was not there. Now if the option is
"automatic" it will add an entry in the parent too ( it will be
successful if there are no no-null fields in the parent apart from the
primary key).
The way to use it now is:
:/*
 * check_primary_key () -- check that key in tuple being
inserted/updated
 *                       references existing tuple in "primary" table.
 * Though it's called without args You have to specify referenced
 * table/keys while creating trigger:  key field names in triggered
table,
 * referenced table name, referenced key field names,type of action
[automatic|dependent]:
 * EXECUTE PROCEDURE
 * check_primary_key ('Fkey1', 'Fkey2', 'Ptable', 'Pkey1', 'Pkey2',
'[automatic|dependent]').
 */
I am attaching the new ../contrib/spi/refint.c file which will do this.
I will be glad to help in case of any problems.

- Anand.

diff --git a/contrib/spi/refint.c b/contrib/spi/refint.c
index ca9ffa728811c9718ae9e30b62427d4d3a7980e4..ca491192975bf2ab5c72b52081a1f9cb4a8bee3c 100644 (file)
--- a/contrib/spi/refint.c
+++ b/contrib/spi/refint.c
@@ -30,9 +30,9 @@ static EPlan *find_plan(char *ident, EPlan ** eplan, int *nplans);
  *                      references existing tuple in "primary" table.
  * Though it's called without args You have to specify referenced
  * table/keys while creating trigger:  key field names in triggered table,
- * referenced table name, referenced key field names:
+ * referenced table name, referenced key field names,type of action [automatic|dependent]:
  * EXECUTE PROCEDURE
- * check_primary_key ('Fkey1', 'Fkey2', 'Ptable', 'Pkey1', 'Pkey2').
+ * check_primary_key ('Fkey1', 'Fkey2', 'Ptable', 'Pkey1', 'Pkey2','[automatic|dependent]').
  */
 
 HeapTuple                                              /* have to return HeapTuple to Executor */
@@ -41,9 +41,10 @@ check_primary_key()
        Trigger    *trigger;            /* to get trigger name */
        int                     nargs;                  /* # of args specified in CREATE TRIGGER */
        char      **args;                       /* arguments: column names and table name */
-       int                     nkeys;                  /* # of key columns (= nargs / 2) */
+       int                     nkeys;                  /* # of key columns (= (nargs-1) / 2) */
        Datum      *kvals;                      /* key values */
        char       *relname;            /* referenced relation name */
+       char       *action;             /* action on insert or update*/
        Relation        rel;                    /* triggered relation */
        HeapTuple       tuple = NULL;   /* tuple to return */
        TupleDesc       tupdesc;                /* tuple description */
@@ -84,10 +85,14 @@ check_primary_key()
        nargs = trigger->tgnargs;
        args = trigger->tgargs;
 
-       if (nargs % 2 != 1)                     /* odd number of arguments! */
-               elog(ERROR, "check_primary_key: odd number of arguments should be specified");
+       if ((nargs-1) % 2 != 1)                 /* odd number of arguments! */
+               elog(ERROR, "check_primary_key: even number of arguments should be specified");
 
-       nkeys = nargs / 2;
+       nkeys = (nargs-1) / 2;
+       action=args[nargs -1];
+       if (strcmp(action,"automatic") && strcmp(action,"dependent"))
+               elog(ERROR,"check_primary_key: unknown action");
+       nargs=nargs-1;
        relname = args[nkeys];
        rel = CurrentTriggerData->tg_relation;
        tupdesc = rel->rd_att;
@@ -198,9 +203,62 @@ check_primary_key()
        /*
         * If there are no tuples returned by SELECT then ...
         */
-       if (SPI_processed == 0)
+       if (SPI_processed == 0 && strcmp(action,"dependent")==0)
                elog(ERROR, "%s: tuple references non-existing key in %s",
                         trigger->tgname, relname);
+       else if (strcmp(action,"automatic")==0) 
+       {
+               /* insert tuple in parent with only primary keys */
+               /* prepare plan */
+               void       *pplan;
+               char            sql[8192];
+
+               /*
+                * Construct query:INSERT INTO relname (Pkey1[,Pkey2]*) values ($1,$2..); 
+                */
+               sprintf(sql, "insert into %s ( ", relname);
+               for (i = 0; i < nkeys; i++)
+               {
+                       sprintf(sql + strlen(sql), "%s%s ", args[i + nkeys + 1],(i<nkeys-1) ? ",":"");
+               }
+               sprintf(sql+strlen(sql),") values (");
+               for (i=0;i<nkeys; i++)
+               {
+                       sprintf(sql+strlen(sql),"$%d%s ",i+1,(i<nkeys-1) ? ",":"");
+               } 
+               sprintf(sql+strlen(sql),")");
+
+               /* Prepare plan for query */
+               pplan = SPI_prepare(sql, nkeys, argtypes);
+               if (pplan == NULL)
+                       elog(ERROR, "check_primary_key: SPI_prepare returned %d", SPI_result);
+
+               /*
+                * Remember that SPI_prepare places plan in current memory context
+                * - so, we have to save plan in Top memory context for latter
+                * use.
+                */
+               pplan = SPI_saveplan(pplan);
+               if (pplan == NULL)
+                       elog(ERROR, "check_primary_key: SPI_saveplan returned %d", SPI_result);
+               plan->splan = (void **) malloc(sizeof(void *));
+               *(plan->splan) = pplan;
+               plan->nplans = 1;
+       /*
+        * Ok, execute prepared plan.
+        */
+       ret = SPI_execp(*(plan->splan), kvals, NULL, 1);
+       /* we have no NULLs - so we pass   ^^^^   here */
+
+       if (ret < 0)
+               elog(ERROR, "check_primary_key: SPI_execp returned %d", ret);
+
+       /*
+        * If there are no tuples returned by INSERT then ...
+        */
+       if (SPI_processed == 0)
+               elog(ERROR, "error: can't enter automatically in %s",relname);
+       }
 
        SPI_finish();