Get fresh object from xPDO question

Is there an easy way in xPDO to be sure of getting an object from the DB rather than the cache?

It seems that I'm constantly being bitten by instances where a stale version of an object exists in the cache and getObject() or getCollection() pulls the old object. In an extra, I don't want to refresh the whole cache just to get the revised object.

Isn`t there the 3rd parameter which states the cacheFlag, to say modx that it should always load this object from the database?

AFAIK, cacheFlag determines how long the results will be cached *after* you retrieve the object.

I would say, thats not correct.

https://github.com/modxcms/xpdo-core/blob/master/om/xpdoobject.class.php#L414

If the cacheFlag is false, he does not even check the cache. Also the xPDOCriteria could have the cache Flag. Maybe in your code you have to set the cacheFlag of the xPDOCriteria also to false.

Looking at the code, it appears that you're right. I was going by this:




If we're right, you lose the ability to create/update the cache for the object when you ask for the fresh object.

Quote from: BobRay at Feb 13, 2013, 12:41 PM

Looking at the code, it appears that you're right. I was going by this:

* @param boolean|integer $cacheFlag Indicates if the objects should be
     * cached and optionally, by specifying an integer value, for how many
     * seconds.

If we're right, you lose the ability to create/update the cache for the object when you ask for the fresh object.

Not at all, so long as any save() is called without sending false to the $cacheFlag parameter as well.

Now I'm confused. Doesn't this code mean that for any $cacheFlag value other than false or 0 , you'll be getting the object from the cache rather than a fresh object from the DB?



So to get a fresh object, $cacheFlag has to be false. Then this code that updates the cache wouldn't execute, no?




What am I missing?

Quote from: BobRay at Feb 14, 2013, 06:12 PM

Now I'm confused. Doesn't this code mean that for any $cacheFlag value other than false or 0 , you'll be getting the object from the cache rather than a fresh object from the DB?

if ($xpdo->_cacheEnabled && $criteria->cacheFlag && $cacheFlag) {
    $row= $xpdo->fromCache($criteria, $className);
}

So to get a fresh object, $cacheFlag has to be false. Then this code that updates the cache wouldn't execute, no?

if (!$fromCache && $cacheFlag && $xpdo->_cacheEnabled) {
   $xpdo->toCache($criteria, $instance, $cacheFlag);

What am I missing?

You are talking about two different things. If you want to bypass the cache, get the object with cacheFlag set to false. The cache will be ignored completely as you are suggesting, even when saving. The intended use is, get the object with the indicated cacheFlag, either from cache if it exists, or not, then, if from the cache, add/update the cached copy if anything changes and is saved.

It sounds like you're agreeing with me. What I said (or meant to say) was that if you get a fresh object from the DB (by bypassing the cache), the cache won't be updated.

I think I can imagine a case where you'd want to get a recently changed object from the DB *and* have the cache updated for that object, but to do that you'd have to use a separate operation to update the cache for the object -- I guess by getting the object twice.

If you are getting the object with a parameter for a specific caching action, why can't you call save with a different one?