Issue on JS subforms

Gavin Foster omnislist at dataweaver.com
Sun Jul 22 16:35:34 EDT 2018


Hi all,

I’m a bit late coming to this one but I noticed you refer to communication between subforms.
I use a technique called a ‘data observer object’ which I believe was used by Doug Kuyvenhoven years ago and might be useful for inter-subform messaging in this case.

In short:
a) You instantiate an object class at the topmost remote form level.

b) All the subforms register an interest with that object class, stating who they are, what message or event they are interested in and what public method within them to execute. These details are stored in a list variable in the object class.
e.g.
	(i) $cinst.$ref of the subform
	(ii) 'LoadClient' or 'UpdateClient' or ‘DeleteClient'
	(iii) ‘$updateclientmethod’

c) When one of the subforms performs an event, it ‘notifies’ the data observer object of the event, along with a row variable containing the data just affected.
i.e., it sends 2 parameters to the data observer:
	(i) ‘UpdateClient’
	(ii) ivClientRow

d) The data observer, goes through the list of subforms that expressed an interest in the ‘UpdateClient’ event and calls the method in each subform, passing ivClientRow to it.

I don’t think I’ll be able follow up on this conversation this week as I’m on holiday now and trying to avoid reading any emails(!). But I hope this helps and if you want to follow up, please email me privately next week.

I can also talk about the technique at Euromnis this year, so feel free to book your place and let’s get together in Germany!!

Best regards,
Gav


> On 12 Jul 2018, at 11:42, Sten-Erik Björling <s-e.bjorling at enviro.se> wrote:
> 
> Dear Michael,
> 
> Many thanks for this, very useful. My challenge though covers the use of JS subforms within other JS subforms - and even JS subforms in deeper levels. I am evaluating an approach that uses paged panes as “coordinate placeholders” since they can be resized when the user change the browser window size and then use these coordinates to move a “1st level” subform to the right place. Will be somewhat interesting…
> 
> Take care, all the best… And thanks for the tip…
> 
> Stene
> 
> ______
> 
>> On 11 Jul 2018, at 10:06, Michael Monschau <michael at brainydata.co.uk> wrote:
>> 
>> Dear Stene,
>> 
>> Our JS-OWrite document manager example uses a subform with multiple classes. We have a tab control that assigns the $classname when a different tab is clicked. This has two consequences. The one subform field can instantiate and maintain multiple form instances and the subform data is only downloaded the first time it is needed (if it is never needed the data is not downloaded).
>> 
>> As it is a simple matter of assigning the $classname on the client, I can see that this approach would make it possible to be very flexible about which subforms appear where on screen, if one was to use multiple subform fields within different fixed areas of the main form. For example, a navigation list on the left and content on the right. Another user could choose to display them the other way around. 
>> 
>> Regards,
>> Michael
>> 
>> Michael Monschau (Director)
>> Brainy Data Limited
>> 
> 
> 
> 
> Sten-Erik Björling
> Enviro Data
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