Hi Chris, 1) do table forms have any relevance in ORDA anymore?
Sure. Personally I am sticking with them for output forms in user mode, for example. And I'm still including a bare bones input form as well. I wouldn't use it for user-facing production forms. I don’t want to mix ‘classic’ 4D in new projects, and so it seems that I > should use project forms exclusively. What’s your take on that? > I haven't used MODIFY SELECTION in 10+ years. Forms I've made to allow users to create selections have been dialogs with a listbox. I am encapsulating my use of ORDA as I get familiar with it. What's that mean? Within individual methods I don't mix them. As much as possible, and so far it's been possible, I don't mix them in the context of an overall task. So if I've got some update action to do which requires finding records, evaluating and modifying them I'll do all that using ORDA or classic. There's a real temptation to use a classic QUERY 'cause I've been doing that for a long time. But it's worthwhile to learn the ORDA commands for doing the same thing. > 2) Recording Editing with related MANY displayed in a ListBox. ENTITY > SELECTION-STYLE, not classic > In a form, say, that displays an invoice, and the invoice detail is > provided in a ListBox (Collection source), I am concerned about the > situation where a user may delete lines from the Detail (ListBox) and then > cancel the record edit (of the Invoice). It seems that editing the records > (entities) displayed in the ListBox commits the changes as they take place. > Not unless you specifically call entity.save <http://doc.4d.com/4Dv17/4D/17/entitysave.301-3763798.en.html>(). The *entity.save( )* method saves the changes made to the entity in the table related to its dataClass. You must call this method after creating or modifying an entity if you want to save the changes made to it. Does one control this through Transaction control (i.e. so that changes can > be allowed, but not committed until OK’d)? > If so, then how does one do that under ORDA, when one is using entity > selections instead of ‘classic’? > The mechanics of this are what you are accustomed to. ALL RECORDS $selObj:=Create entity selection START TRANSACTION For each ($obj;$selObj) // read: for each $obj is $selObj... If ($obj._ID%2=0) $obj._ID:=$obj._ID-2 $obj.save() End if End for each CANCEL TRANSACTION In this instance each entity has _ID if it's even. Note the explicit save. Since it's run in a transaction and the transaction is canceled the changes aren't written to the datastore (records). In the example you stated let's say you don't call .save() every time there's a change - how do you do it? You want entity.touched() <http://doc.4d.com/4Dv17/4D/17/entitytouched.301-3764513.en.html>. The *entity.touched( )* method tests whether or not an entity attribute has been modified since the entity was loaded into memory or saved. If an attribute has been modified or calculated, the method returns true, else it returns false. You can use this method to determine if you need to save the entity. ALL RECORDS $selObj:=Create entity selection START TRANSACTION --- user stuff happens --- For each ($obj;$selObj) If ($obj.touched()) $obj.save() End if End for each If($groovy) VALIDATE TRANSACTION Else CANCEL TRANSACTION End if > When an INVOICE is to be edited: > > ds.Invoice.lock() > A pessimistic lock isn't necessary for the transaction to work using ORDA. It's important in an existing database to avoid conflicts with 'classic' processes because a pessimistic lock was the only type available before. A note regarding user deletions of lines from a listbox. To be honest I thought I understood how to do this but I just tested it and it's not working. I filed a TAOW case on it asking for explanation so I'm going to wait until I hear from them before saying anything about it. Hope the rest helps. -- Kirk Brooks San Francisco, CA ======================= *We go vote - they go home* ********************************************************************** 4D Internet Users Group (4D iNUG) Archive: http://lists.4d.com/archives.html Options: https://lists.4d.com/mailman/options/4d_tech Unsub: mailto:4d_tech-unsubscr...@lists.4d.com **********************************************************************
