was after. Now I read it, it all makes perfect sense.
T
On Jan 24, 9:38 pm, ShadowCross <adri...@jps.net> wrote:
> Assuming
>
> ModelA hasMany ModelB
> ModelB includes a date column called 'date'
>
> you could try:
>
> $this->ModelA->bindModel(array(
> 'hasOne' => array(
> 'MaxDateModelB' => array(
> 'className' => 'ModelB',
> 'foreign_key => 'model_a_id',
> 'conditions' => 'MaxDateModelB.date IN (SELECT
> MAX(ModelB_2.date) FROM ' . $this->ModelB->table . ' AS ModelB_2 WHERE
> ModelB_2.model_a_id = ModelA.id'
> )
> )
> ), false);
> $this->paginate = array_merge($this->paginate, array(
> 'order' = array('MaxDateModelB.date')
> );
> $this->set('model_as', $this->paginate());
>
> The first line creates a hasOne on-the-fly association with ModelB
> using the alias of MaxDateModelB; note the conditions further
> restricts the records by sub-selecting only the records with the
> MAX(date) from ModelB (I used the alias 'ModelB_2' to avoid any
> conflicts with the "hasMany ModelB" to avoid any confusion with the
> "hasMany ModelB" association) that matches the original ModelA record
> id. I avoid hardcoding the tablename of ModelB and use $this->ModelB->table in case the tablePrefix variable is defined (either in ModelB
>
> or in AppModel). The $reset parameter for bindModel MUST be false,
> since paginate() requires 2 queries.
> The second line actually set the order using the new association
> (MaxDateModelB.date).
>
> While I have used something similar to this (although I define the
> hasOne in the model since I use it in several places), YMMV. You
> should consider creating an (non-unique) index on ModelB using
> (model_a_id, `date`) as the key for performance reasons.
>
> Another alternative, which will be faster if the projected number of
> records in ModelB is significantly large, is to use a "cache" field in
> ModelA similar to counterCache. Basically, add a field in ModelA
> (i.e. max_model_b_date) that gets updated in the afterSave() method of
> ModelB (i.e.
>
> $this->ModelA->updateAll(
> array('ModelA.max_model_b_date' => $this->data['ModelB']
> ['date']),
> array(
> 'ModelA.id' => $this->data['ModelB']['model_a_id'],
> 'ModelA.max_model_b_date < ' => $this->data['ModelB']
> ['date'],
> )
> );
>
> This alternative does require some "data conversion" if you already
> have records in ModelB (you will need to populate the max_model_b_date
> field, but may be do-able in a single SQL statement).
>
> Another consideration is whether the frequency of accessing the
> index() action of the ModelAController is greater than the frequency
> of accessing the add()/edit()/delete() actions of the
> ModelBController. If the ModelA.index() action is going to be used
> several times a day, but the ModelB actions only once a week, I would
> use the "cache" field method, since the additional overhead on the
> database is incurred when you insert/update/delete on ModelB. If,
> however, you expect a lot of transactions on ModelB, but use
> ModelA.index() infrequently (for example: ModelB represents individual
> users' activity on a popular games site, including their scores, and
> ModelA.index() is used for a weekly rankings report), I would go with
> the custom hasOne method outlined earlier, since the "cache" field
> method requires 2 sql updates to the custom hasOne's 1 sql update.
--
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