Question

For storing user-defined bookmarks on some site, I have a table with the composite key:

CREATE TABLE bookmarks (
    user_id int not null,
    book_id int not null,
    page_id int,
    ...
);
CREATE UNIQUE INDEX ON bookmarks(user_id, book_id, page_id);

Note, that page_id can be NULL, and user_id and book_id can not. When page_id is null, the bookmark is set for the whole book, otherwise – for certain page.

Corresponding ActiveRecord class defines some relations:

public function relations() {
    return array(
        "user"  => array(self::BELONGS_TO, "User",     "user_id"),
        "book"  => array(self::BELONGS_TO, "Book",     "book_id"),
        "page"  => array(self::BELONGS_TO, "Page",     "page_id"),
    );
}

and a primaryKey() method::

public function primaryKey() {
    return array("user_id", "book_id", "orig_id");
}

Now I want to get all bookmarks for the whole book for some user. So, I do:

$bookmarks = Bookmark::model()->findAll(array(
    "condition" => "t.user_id = :user_id AND t.page_id IS NULL",
    "params" => array(":user_id" => 1),
));

It works great, returning 4 records, but obviously, I want to use some related data from books table:

$bookmarks = Bookmark::model()->findAll(array(
    "with" => "book",
    "condition" => "t.user_id = :user_id AND t.page_id IS NULL",
    "params" => array(":user_id" => 1),
));

and now I get 0 records (count($bookmarks) == 0), although the generated SQL statement selects all needed data, it is just not recognised by CActiveRecord class. Another weird thing is, that when I try to fetch all page bookmarks, everything is okay:

$bookmarks = Bookmark::model()->findAll(array(
    "with" => "book",
    "condition" => "t.user_id = :user_id AND t.page_id IS NOT NULL",
    "params" => array(":user_id" => 1),
));

What am I doing wrong? How to make expression in the second example return some data? PHP 5.4.0, Yii 1.1.8, PostgreSQL 9.1.4, +32°C outside.

Answer 1

Your issue may be solved in this way:

1. Add a surrogate PK to the Bookmark table (e.g. auto-incremental sequence).

2. Remove primaryKey() function.

You may also use more convenient code:

public function relations()
{
    return array(
        //...
        'wholeBook' => array(self::BELONGS_TO, 'Book', 'book_id', 'on'=>"page_id IS NULL", 'joinType'=>'INNER JOIN'),
        //...
    );
}

Then in the controller just:

$bookmarks = Bookmark::model()->with('wholeBook')->findAllByAttributes(array('user_id'=>1));

As a matter of fact, with UNIQUE key instead of PRIMARY and primaryKey() you use hack to evade impossibility of using NULL column in composite PKs.
ActiveRecord is a sort of ORM, so any logic in SQL must be translated into AR (Yii automatically loads DB schemas), and it must be correct logic.

If I were you I’d normalize SQL to something like this:

Because of those are two different types of bookmarks with different relations. You should join them only in view logic, not in relation structure. IMHO