Siarhei!
We had started to work with QxTransformer and picked the
"DataProvider"-stuff here as a starter for our own implementation. I just
summarize a few issues that we encountered here. Please feel free to adapt
these issue to your concept :
1) Internal Transport-Format
The usage of "sub-arrays" for the data-transport is not very handy. The
current "MDataManager.js" will (JSON-)serialize the data in structures like
obj.TextFieldName.value = 'data;
as for ComboBoxes this will be :
obj.ComboBoxFieldName.value = 'data;
obj.ComboBoxFieldName.selected.value = 'data;
than for Checkboxes:
obj.CheckBoxFieldName.checked = true/false;
As for writing a backend (e.g. a database storage) this is not very handy,
as you have to know how get/set the data depending on the clientside used
widget. So we remodeled this part to always return a "flat" value, so the
clientside widget is responsible how to "bind" the value to its internal
"values".
So we have only :
obj.TextFieldName = 'data'; // uses setValue
obj.ComboBoxFieldName = 123; // selects the ListItem with the value 123
obj.CheckBoxFieldName = 1; // transforms to setChecked(true);
This is much easier on the backside as a "SQL-resultset" could be mapped
back and force.
2) Error Handling
Normally a backend would not only store the data but also add some
validation logic. So we changed the return format of the backend to give the
ability to return "validation-message" back to the client. This regards
simply return "error-message" that are routed back to the widget. So the
widget gets an event (implemented with a MixIn) with the validation error.
The widget then might do an action e.g. changing the background-color,
showing an alert, popup a tooltip, or delegate the error to another widget.
(Here we have a .NET inspired ValidationError-Widget).
3) Formbased Validation Errors
In conjunction to 2) we have also situation where the validation has to be
done on a form-based level. E.g. a "Change Password"-UseCase would need to
check if 2 password fields ("repeat password") have the same values. Here a
validation-feedback might need to postback the validation to 2 client-side
widgets. Our implementation will return also a "Script"-Field that could be
eval'ed and does the feedback to the user, e.g. :
(done on the serverside)
result.script = '
this.pwd1.setColor('red');
this.pwd2.setColor('red');
alert('The passwords have to match');
';
----
The clientside then just does an eval(result.script);
greetings
Carsten Harnisch
-----------------------------------
InTradeSys Limited
-----Ursprüngliche Nachricht-----
Von: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Im Auftrag von Siarhei
Barysiuk
Gesendet: Mittwoch, 25. Juli 2007 19:46
An: qooxdoo Development
Cc: Christian Boulanger
Betreff: [qooxdoo-devel] Data Binding Mechanism. Qooxdoo and QxTransformer.
Hello folks!
For few last day I was thinking about data binding functionality for qooxdoo
(including 'plain html forms'
emulation and auto completion) and I would like to present results of my
work for discussion.
I will be really appreciated for any remarks and suggestions from all
developers. If you have any questions fell free to ask. Hope it will be
interesting for you.
I would like to notice that this is only concept. I've already implemented
few parts but not everything.
I'm working at this task at present. This is last part of work before
initial release of QxTransformer.
(In document I didn't pay attention to backend because you can implement
backend in different ways.
Would like to concentrate only on JavaScript qooxdoo API and QxTransformer
syntax.)
The concept is based on functionality which we have now in QxTransformer
(written by Christian Boulanger) with improvements (which make API more
flexible).
Please find attached Data Binding Mechanism Concept document.
Thanks for any remarks and suggestions.
Best regards,
Siarhei Barysiuk
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