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 property WHERE prname = 'name';
INSERT INTO itemproperty (ipItemid,ipPropertyid,ipValue)
SELECT currval('item_itemid_seq'),propertyid,'XP453-2421'
FROM property WHERE 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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