One approach which works well for this type of thing is where you query the values after you've done the update or insert and just populate the changed properties in your instance. LC DS lets the assembler modify properties which are not defined on the client. The most common example is that you often set identity properties in your "createItem" method after they are assigned in the database. You also can do this for version properties which get updated on each change though and certainly a "last modified" timestamp would work this way. In your createItem method you do not need to do anything other than updating the property in the instance passed in as it picks up any changed properties. In the updateItem method, you do need to ensure the changed property is in the "changes" list passed to your assembler (or just add it if it is not).
Since you are using the hibernate assembler, you'd probably need to sub-class the hibernate assembler and put this logic into the subclass after performing the create/update using the super class. The other way people use triggers is to modify rows or columns that store data for unrelated objects... for that you'd have to use the DataServiceTransaction api in Java to mirror what is being done in the database if you want clients to track those changes. Unfortunately that means that you have to mirror the trigger logic in Java. There's no easy way that I know of to have the trigger notify the Java code so this can be done automatically. Jeff ________________________________ From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Kevin Sent: Monday, February 11, 2008 1:10 PM To: [email protected] Subject: [flexcoders] LCDS and triggers, auto inserts or updates of timestamp columns I am wondering how successful triggers are when used with LCDS & DMS? Should I expect to run into a bunch of DataService conflicts with this or are they safe to use. I am not thinking about anything too crazy, even just basic timestamp updating would be nice to implement on the database rather than in Java or on the client. There are some basic triggers I would love to enable as well. Just looking for some quick opinions/advice before I enable these on my database. Thanks, Kevin
