Why there is no Tridion page template system metadata published to broker database?

Question

We are using Tridion 2011 SP1 HR1 and New UI.

We would like to generate new UI JSON tags using our Java framework based on the Java content delivery API: Tridion delivery framework (TDF).

The JSON tag for the page should contain the PageTemplateModified parameter.

<!-- Page Settings: {"PageID":"tcm:48-84852-64",
    "PageModified":"2013-02-28T15:04:30",
    "PageTemplateID":"tcm:48-24343-128",
    "PageTemplateModified":"2013-02-27T17:11:31"} 
 -->

But when a Tridion page or a Tridion page template is published to the broker database, the zip sent to the deployer does not contain any information about the page template. In the broker DB, ITEMS table does not contain any rows for page templates.

It is easy to verify using the following SQL query on the broker DB:

select * from items where item_type = 128

Is there a reason, why?

[edit]

I am speaking about system metadata.

Answer 1

This is very subjective,and not really a fit for Stack Overflow consider asking it at https://tridion.stackexchange.com/grant-beta-access?key=63880f9cbf452c62f726770209533893

I think the only way you will be able to get the modification date of a PT into your rendered page output would be to add the data to your page (or page meta) at publish time.

To answer the Why? Part of your Q, probably nobody thought of a reason for it, so it was never designed that way.

Answer 2

I was going to reply to the thread under Chris' answer, but it became too long...

The Last modified date setting in the XPM JSON cannot be the real last modified date, and I'll explain why.

When you load Experience Manager, it will quickly go through the various ""LastModified" settings in the JSON to compare with what is stored in the CM and determine if your page is up to date. If you published this page in December last year, then modified the template in January, the dates should not match - and XPM will let the editor know that "this page is not up to date, click here to reload".

If you would now change that last modified date "on the fly" to be the real last modified date of the template as opposed to the last modified date of the template at the time this page was published then XPM will not detect that there was a change made to the template on the CM and the editors may have unexpected results, like changing the value of a field, reload, and suddenly their sidebar is on the left instead of being on the right.

Hope this helps