Passing a list of pairs to a PL/PGSQL function

Hi,
I am scratching my head at a neat way of doing an update function for my 
db.

-- Here is a sketch schema

CREATE TABLE item ( itemid serial, PRIMARY KEY (itemid)
);

CREATE TABLE property ( propertyid serial, prName text, UNIQUE(prName), PRIMARY KEY(propertyid)
);

CREATE TABLE itemproperty ( itempropertyid serial, ipItemid int REFERENCES item(itemid), ipPropertyid int REFERENCES
property(propertyid),ipValue text, UNIQUE(ipItemid,ipPropertyid), PRIMARY KEY(itempropertyid)
 
);

-- Sample data

INSERT INTO property (prname) VALUES('name');
INSERT INTO property (prname) VALUES('rank');
INSERT INTO property (prname) VALUES('serial');
INSERT INTO item (itemid) VALUES(nextval('item_itemid_seq'));
INSERT INTO itemproperty (ipItemid,ipPropertyid,ipValue)SELECT currval('item_itemid_seq'),propertyid,'John Wayne'FROM
propertyWHERE prname = 'name';
 
INSERT INTO itemproperty (ipItemid,ipPropertyid,ipValue)SELECT currval('item_itemid_seq'),propertyid,'XP453-2421'FROM
propertyWHERE prname = 'serial';
 


I want to write a function that will update itemproperty with a new set 
of property name/value pairs.
Any new property name's that appear should be inserted, any old propery 
names that no longer appear should be deleted, and any existing values 
should be updated.

I am not quite sure where to start.

If I have an update function that takes (int,text,text) as args where $1 
is itemid, $2 is a list of comer separated prnames and $3 is a list of 
comer separated ipvalues, then I can do the Delete okay, but the insert 
and update become difficult.

If I have an update function that takes (int,text[][]) as args where $2 
is an array of prname,ipvalue pairs then the update is easy, but the 
delete and insert become harder I think.

Which route is more promising?

--
Best Regards
David Stanaway
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