Question

Using doctrine 2.1 (and zend framework 1.11, not that it matters for this matter), how can I do post persist and post update actions, that involves re-saving to the db?

For example, creating a unique token based on the just generated primary key’ id, or generating a thumbnail for an uploaded image (which actually doesn’t require re-saving to the db, but still) ?

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EDIT – let’s explain, shall we ?

The above is actually a question regarding two scenarios. Both scenarios relate to the following state:

Let’s say I have a User entity. When the object is flushed after it has been marked to be persisted, it’ll have the normal auto-generated id of mysql – meaning running numbers normally beginning at 1, 2, 3, etc..
Each user can upload an image – which he will be able to use in the application – which will have a record in the db as well. So I have another entity called Image. Each Image entity also has an auto-generated id – same methodology as the user id.

Now – here is the scenarios:

1. When a user uploads an image, I want to generate a thumbnail for that image right after it is saved to the db. This should happen for every new or updated image.
   Since we’re trying to stay smart, I don’t want the code to generate the thumbnail to be written like this:

   $image = new Image();
   …
   $entityManager->persist($image);
   $entityManager->flush();
   callToFunctionThatGeneratesThumbnailOnImage($image);

   but rather I want it to occur automatically on the persisting of the object (well, flush of the persisted object), like the prePersist or preUpdate methods.

2. Since the user uploaded an image, he get’s a link to it. It will probably look something like: http://www.mysite.com/showImage?id=[IMAGEID].
   This allows anyone to just change the imageid in this link, and see other user’s images.
   So in order to prevent such a thing, I want to generate a unique token for every image. Since it doesn’t really need to be sophisticated, I thought about using the md5 value of the image id, with some salt.
   But for that, I need to have the id of that image – which I’ll only have after flushing the persisted object – then generate the md5, and then saving it again to the db.

Understand that the links for the images are supposed to be publicly accessible so I can’t just allow an authenticated user to view them by some kind of permission rules.

Answer 1

In the end, I listened to @Arms who commented on the question.
I started using a service layer for doing such things.
So now, I have a method in the service layer which creates the Image entity. After it calls the persist and flush, it calls the method that generates the thumbnail.

The Service Layer pattern is a good solution for such things.