Re: Choosing which column to use with DB_DataObject::joinAdd()

Well, I found a way around the problem, but it's nasty and hacky and I'm sure there must be a better way...? <snip> global $_DB_DATAOBJECT; if ($direction == 'out') { $friend->from_id = $person_id; $person->joinAdd($friend); // Should join on friend.to_id=person.id } else { $friend->to_id = $person_id; unset($_DB_DATAOBJECT['LINKS'][$database][$friend->__table]['to_id']); $_DB_DATAOBJECT['LINKS'][$database][$friend->__table]['from_id'] = $person->__table.':id'; $person->joinAdd($friend); // Should join on friend.from_id=person.id } </snip> On 6/28/05, Phil Gyford <gyford@gmail.com> wrote: > I'm having a problem using DB_DataObject's joinAdd(), with a table > that has two ways of joining another. I think what I want to do is > possible, but I can't understand either the joinAdd() documentation or > the error message. > > I have a table (person) representing a person: > id > name > > And a table (friend) representing one-way relationships between those people: > id > from_id > to_id > > My databasename.links.ini file has this: > [person] > id = friend.from_id > id = friend.to_id > > [friend] > from_id = person.id > to_id = person.id > > > I then have a getFriends() function. I can pass this a person_id and a > 'direction', either 'in' or 'out. This will return either a list of > people who call this person a friend ('in') or people who this person > calls a friend ('out'): > > function getFriends ($person_id, $direction) > { > $person =& DB_DataObject::factory('person'); > $friend =& DB_DataObject::factory('friend'); > > if ($direction == 'out') { > $friend->from_id = $person_id; > $person->joinAdd($friend); // Should join on friend.to_id=person.id > } else { > $friend->to_id = $person_id; > $person->joinAdd($friend); // Should join on friend.from_id=person.id > } > > // [Code for finding and returning the results in an array here] > } > > Obviously, DB_DataObject can't magically know whether to join on > from_id or to_id, so it only tries one way. I've tried doing things > with the fourth argument one can pass to joinAdd() but don't > understand the docs and always get this error: > > "joinAdd: You cannot target a join column in the 'link from' table > (dvb_friend). Either remove the fourth argument to joinAdd() > (from_id), or alter your links.ini file." > > I don't understand this either... Can anyone help me set which column > to join with? > > Many thanks. > Phil >