On Thu, May 21, 2009 at 12:58 PM, Peter Rabbitson <[email protected]> wrote:
> Zbigniew Lukasiak wrote:
>> On Thu, May 21, 2009 at 9:52 AM, Peter Rabbitson <[email protected]> 
>> wrote:
>>> Zbigniew Lukasiak wrote:
>>>> My tests are all passing - but I noticed that resolve_condition in
>>>> ResultSource is now marked as private method and warns.  I can
>>>> understand why - as it has rather tricky interface - but is there any
>>>> chance to have a public equivalent?  That is something that would
>>>> compute the values of columns in the related ResultSet set when I do
>>>> $object->search_related( 'rel_name', {} )?
>>>>
>>> These interfaces were never meant to be public, thus were properly
>>> re-hidden. Please provide a justification use case of why an end
>>> user would need this method available.
>>
>> Sure - so I have an object, a relation on that object and a hash - I
>> want to get the related object as identified by the hash - and if it
>> does not exits then I need to create it.  I guess this is a familiar
>> problem to you - the tricky part is when ther primary key is
>> automatically incremented by the database (or gets set from another
>> related table that has automatically incremented id - this is the
>> tricky  might-have case from 96multi_create).  Currently I do that by
>> using resolve_condition and checking lots of things.
>>
>> I guess it would be even better if I could just do
>> $object->find_related( 'rel_name', $hash_ref ) and get an exception if
>> the $hash_ref (and the relationship) is not enough to identify the
>> related object.  Currently, as we know,  find will try to do it's best
>> - but if there is not enough info - then it will return a random row
>> (and issue a warning if there are more rows matching - but catching
>> this warning is not enough because it does not need to be issued - for
>> example there can be just one row in the table).
>>
>> To be more concrete let's say that the related table has columns 'id'
>> and 'name'.
>>
>> $object->find_related( 'rel_name', { name => 'some name' } )
>>
>> If the relation does not bind the 'id' - then this will find a random
>> row.  I need to know if the relation does bind the 'id'.
>>
>> I know - this is the same old thing - but it has not been solved yet
>> in a satisfactory way (you did it in multicreate - but it uses even
>> more private calls - so I am out of luck in using your methods).
>>
>
> No it isn't. find_related should always add the relationship columns to
> the WHERE condition. Please show a standalone test-case where find_related
> returns random crap (including the generated SQL).

I've never said that it does not add the relationship columns - it
does.  The problem is with deciding if the provided data is enough
(together with the added relationship columns) for a find call.  The
simple example is of a has_many relation, lets say user has_many books
- then $user->find_related( 'books', {} ) is not a correct call to
find (and in this case it will return a random book from the set the
user owns), but $book->find_related( 'owner', {} ) is a correct call.

The example code is attached.  Output (with DBIC_TRACE set) is:

CREATE TABLE book (
  id INTEGER PRIMARY KEY NOT NULL,
  name varchar(100) NOT NULL,
  owner integer
):
CREATE TABLE usr (
  id INTEGER PRIMARY KEY NOT NULL,
  name varchar(100) NOT NULL
):
INSERT INTO usr ( name) VALUES ( ? ): 'aaaa'
INSERT INTO book ( name, owner) VALUES ( ?, ? ): 'bbbb', '1'
INSERT INTO book ( name, owner) VALUES ( ?, ? ): 'bbbb', '1'
User id: 1
SELECT me.id, me.name, me.owner FROM book me WHERE ( me.owner = ? ): '1'
DBIx::Class::Relationship::Base::find_related(): Query returned more
than one row.  SQL that returns multiple rows is DEPRECATED for ->find
and ->single at find_relate_example.pl line 81
DBSchema::Book


-- 
Zbigniew Lukasiak
http://brudnopis.blogspot.com/
http://perlalchemy.blogspot.com/

Attachment: find_relate_example.pl
Description: Perl program

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