FW: [CForms binding] access to model data from repeater row widget
This is probably a question more suitable for the dev-list... -Original Message- From: Bruyn Bill Sent: Monday, April 10, 2006 3:18 PM To: 'users@cocoon.apache.org' Subject: [CForms binding] access to model data from repeater row widget Taken from: http://www.planetcocoon.com/node/2423#comment >Re: [CForms binding] access to model data from repeater row widg >Sylvain Wallez - June 21, 2005 - 06:50 >>Mark Lundquist wrote: >>Hi, >> >>Here is a scenario that I keep finding myself dealing with... >> >>Some repeater is bound to a collection, and also contains one or more >>widgets that are /not/ bound to the collection elements. For instance, >>there might be a checkbox that means "do something to/with the thing >>in this row". After accepting the form, the processing entails >>iterating through the rows and doing something something with the >>corresponding object from the model layer, which means I need to be >>able to find/access that object. > > >So in essence, you want to act on the selected rows, right? I >encountered this already, and I've been thinking to explicitely add the >selection concept to repeaters. That selection would be defined by a >boolean field present on each row. Note that a boolean field doesn't >necessarily means rendering as a checkbox. It can also be some >highlighting of selected rows. > >That would lead to > > > > > > > >Repeater actions such as "delete-rows" would then no more have a need >to >be given the select widget's name as of today. > >And even more, repeater actions could have constraints on the selection >size, such as single-selection, multiple-selection, leading these >actions to be disabled if their associated constraint isn't met. > >And finally, we may be able to specify on repeater bindings if they >have >to act on the whole repeater on just on the selection. Has this gotten any traction? Is it still reasonable? Thanks, Bill
Re: [CForms binding] access to model data from repeater row widget
Mark Lundquist wrote:
Hi Sylvain, thx for your reply...
However...
I realized that I have a nomenclature clash with my choice of
the name "model". I've been using the v2 API for a long time,
so I forgot in v1, there is a Form.model property that
denotes
the widget value tree.
The "model" property is only available on the toplevel form JS
object, so there may not be a clash.
It's not a hard "name clash", but it is a nomenclature clash in that
it's a different sense of the term "model". My new row "model"
property is truly the "model", as in "MVC" or as in
"loadFormFromModel()". The v1 "model" is "model" in terms of
"formmodel", I guess. I just think it's too confusing to have both
senses. I actually sort of wish the v1 "model" were called something
else, because it isn't the model /a la/ MVC.
You're right. The "form.model" is actually the value tree.
Maybe form.model should be renamed to "form.value"! Then you would
have these two expressions that mean the same thing (just as they look
like they should! :-):
form.value.foobar
and
form.lookupWidget('foobar').value
, right? :-)
Yes, and also "form.value.foo.bar.baz" and
"form.lookupWidget('foo/bar/baz').value". Naming it "form.values"
(plural) sounds better.
But for now in my working version of the code I settled on "rowModel"
to expose the row model object in Flowscript and JXT.
Now then, the following exchange has me totally confused:
It doesn't seem good to me to provide at the API level a way to
link the form to the data model,
No, no, it /is/ good... :-)
[ ...my rambling snipped...]
However, there are some uses cases where this makes sense. You can
then use widget attributes (see get/setAttribute) to attach some
application data of your liking to any widget, including repeater
rows.
See, that's the problem, this is what I have to deal with currently
:-)... I have two parallel structures: a Collection, and a Repeater.
If the Repeater does not give me a "view" to its collection, then I
have to do some kind of iteration to create associations somewhere
between the repeater rows and the collection elements, and this just
feels silly and wasteful. I've done it this way, decorating the
repeater rows with handles to the model data, and I just think that
since the binding layer is already iterating across the collection,
it should do this decoration for me! :-).
Yes. That's the idea behind the "bound repeater binding" idea
Reinhard pointed to.
Right. Which was your idea, and which I think I have gone and
implemented before I knew that somebody else had thought of it :-)...
Or have I not? Maybe I am misunderstanding Reinhard's reference and
it isn't really the same thing... or maybe you are misunderstanding
me, and thinking it's not the same thing, but it really _is_? :-)
Are you saying, "Ah yes, you're right... I thought of this before, and
now I remember why it _is_ a good idea (+1! :-)" ?
Or — are you saying "Ah, it looks like I did think of this too once,
but now on second thought I'm not so sure it was a good idea" ?
LOL! I of course remember this was my idea, and I still think it is good.
What doesn't seem good however, is to provide a way to link the data
model and the form, _without going through the binding_. It is ok for
some bindings to use widgets attributes are storage areas for their
stuff, but it isn't ok IMO for the _widget_ API to know about
application data.
I could live with there being a "callback" facility in the repeater
binding language, e.g. within ... know
what I mean? But that's sort of beyond my ability to implement, and
I was looking for something that I could actually do :-)
Extending the repeater binding to keep the connection to the data
model may be easier, no?
Well, it certainly was awfully easy :-) Tell you what, the change is
so ridiculously small, I'll just attach the diffs (they are against
src/blocks/forms/java/org/apache/cocoon/forms) and you can see if
we're talking about the same thing. At first this amounted to about 6
lines of code added, before I added the convenience flowscript
function (that I had mentioned in the original post that I wanted to
add... this doubled :-) the size of the mod). BTW, this function —
'getRowModel()' — I only added it in v2 ('cuz that's what I'm using!
:-). When I looked at v1's ScriptableWidget, I hesitated when I saw
that there are so few javascript functions defined there, and I wasn't
sure if this is really the right idiom for v1... Care to comment?
Well, this is exactly what I consider as wrong above :-)
That's the binding job to possibly use widget attributes to store data
that helps later on the form's save. But the form itself shouldn't have
to care about it.
So the changes should be in RepeaterBinding, and not in Repeater itself.
Sylvain
--
Sylvain Wallez
Re: v2 (was Re: [CForms binding] access to model data from repeater row widget)
Mark Lundquist wrote: Hey, this morning I remembered what started me down the v2 path, as I was replying to a guy on the users' list. It was that in v2, I can set someWidget.onValidate to a function that is nested inside the form controller flowscript function, where it can access that function's local variables. (Here's that mail: http://marc.theaimsgroup.com/?l=xml-cocoon- users&m=111954841402175&w=2... I mention a way that might work in v1 that I hadn't thought of until today as I was composing that!) Ah yes. I'll add this to V1 as well. Sylvain -- Sylvain WallezAnyware Technologies http://apache.org/~sylvainhttp://anyware-tech.com Apache Software Foundation Member Research & Technology Director
Re: [Cforms] "selectability" intrinsic to RepeaterRow? (was Re: [CForms binding] access to model data from repeater row widget)
Mark Lundquist wrote: On Jun 22, 2005, at 2:17 AM, Sylvain Wallez wrote: Mark Lundquist wrote: On Jun 20, 2005, at 11:42 PM, Sylvain Wallez wrote: [8
Re: [CForms binding] access to model data from repeater row widget
Hi Sylvain, thx for your reply...
However...
I realized that I have a nomenclature clash with my choice
of
the name "model". I've been using the v2 API for a long
time,
so I forgot in v1, there is a Form.model property that
denotes
the widget value tree.
The "model" property is only available on the toplevel form JS
object, so there may not be a clash.
It's not a hard "name clash", but it is a nomenclature clash in that
it's a different sense of the term "model". My new row "model"
property is truly the "model", as in "MVC" or as in
"loadFormFromModel()". The v1 "model" is "model" in terms of
"formmodel", I guess. I just think it's too confusing to have both
senses. I actually sort of wish the v1 "model" were called something
else, because it isn't the model /a la/ MVC.
You're right. The "form.model" is actually the value tree.
Maybe form.model should be renamed to "form.value"! Then you would
have these two expressions that mean the same thing (just as they look
like they should! :-):
form.value.foobar
and
form.lookupWidget('foobar').value
, right? :-)
But for now in my working version of the code I settled on "rowModel"
to expose the row model object in Flowscript and JXT.
Now then, the following exchange has me totally confused:
It doesn't seem good to me to provide at the API level a way to
link the form to the data model,
No, no, it /is/ good... :-)
[ ...my rambling snipped...]
However, there are some uses cases where this makes sense. You
can
then use widget attributes (see get/setAttribute) to attach some
application data of your liking to any widget, including repeater
rows.
See, that's the problem, this is what I have to deal with currently
:-)... I have two parallel structures: a Collection, and a Repeater.
If the Repeater does not give me a "view" to its collection, then I
have to do some kind of iteration to create associations somewhere
between the repeater rows and the collection elements, and this just
feels silly and wasteful. I've done it this way, decorating the
repeater rows with handles to the model data, and I just think that
since the binding layer is already iterating across the collection,
it should do this decoration for me! :-).
Yes. That's the idea behind the "bound repeater binding" idea Reinhard
pointed to.
Right. Which was your idea, and which I think I have gone and
implemented before I knew that somebody else had thought of it :-)...
Or have I not? Maybe I am misunderstanding Reinhard's reference and it
isn't really the same thing... or maybe you are misunderstanding me,
and thinking it's not the same thing, but it really _is_? :-)
Are you saying, "Ah yes, you're right... I thought of this before, and
now I remember why it _is_ a good idea (+1! :-)" ?
Or — are you saying "Ah, it looks like I did think of this too once,
but now on second thought I'm not so sure it was a good idea" ?
I could live with there being a "callback" facility in the repeater
binding language, e.g. within ... know
what I mean? But that's sort of beyond my ability to implement, and I
was looking for something that I could actually do :-)
Extending the repeater binding to keep the connection to the data
model may be easier, no?
Well, it certainly was awfully easy :-) Tell you what, the change is
so ridiculously small, I'll just attach the diffs (they are against
src/blocks/forms/java/org/apache/cocoon/forms) and you can see if we're
talking about the same thing. At first this amounted to about 6 lines
of code added, before I added the convenience flowscript function (that
I had mentioned in the original post that I wanted to add... this
doubled :-) the size of the mod). BTW, this function — 'getRowModel()'
— I only added it in v2 ('cuz that's what I'm using! :-). When I
looked at v1's ScriptableWidget, I hesitated when I saw that there are
so few javascript functions defined there, and I wasn't sure if this is
really the right idiom for v1... Care to comment?
Cheers,
—ml—
rowModel.diff
Description: Binary data
Re: v2 (was Re: [CForms binding] access to model data from repeater row widget)
On Jun 23, 2005, at 2:25 AM, Sylvain Wallez wrote:
One thing I don't care so much for in v2 is the idiom of attaching
view data as properties of the widget tree root. The minimalist
approach (losing 'bizData') was clever, but in actual practice I find
that I really like having one locus of transfer of data between the
flowscript and the presentation, so I usually end up with something
like this anyway:
w.viewData =
{
schtuff: foobar,
etc:otherStuff
};
form.showForm ('whatev');
Uh? Didn't knew about that, and looks hacky IMO.
Ex-hacktly! :-)
BTW, why do you prefer v2 rather than v1?
Hey, this morning I remembered what started me down the v2 path, as I
was replying to a guy on the users' list. It was that in v2, I can set
someWidget.onValidate to a function that is nested inside the form
controller flowscript function, where it can access that function's
local variables. (Here's that mail:
http://marc.theaimsgroup.com/?l=xml-cocoon-
users&m=111954841402175&w=2... I mention a way that might work in v1
that I hadn't thought of until today as I was composing that!)
cheers,
—ml—
[Cforms] "selectability" intrinsic to RepeaterRow? (was Re: [CForms binding] access to model data from repeater row widget)
On Jun 22, 2005, at 2:17 AM, Sylvain Wallez wrote: Mark Lundquist wrote: On Jun 20, 2005, at 11:42 PM, Sylvain Wallez wrote: [8
Re: v2 (was Re: [CForms binding] access to model data from repeater row widget)
Mark Lundquist wrote:
On Jun 21, 2005, at 8:41 AM, Mark Lundquist wrote:
On Jun 20, 2005, at 11:42 PM, Sylvain Wallez wrote:
BTW, why do you prefer v2 rather than v1?
<..schnip!..>
One thing I don't care so much for in v2 is the idiom of attaching
view data as properties of the widget tree root. The minimalist
approach (losing 'bizData') was clever, but in actual practice I find
that I really like having one locus of transfer of data between the
flowscript and the presentation, so I usually end up with something
like this anyway:
w.viewData =
{
schtuff: foobar,
etc:otherStuff
};
form.showForm ('whatev');
Uh? Didn't knew about that, and looks hacky IMO.
...and so I guess I'd rather have it as an explicit parameter (and
also not needing to have 'viewData.' at the head of the expression
path within the JX template).
While on the subject... since I am "Mr. Anal Nomenclature Pants", I
would vote for changing 'bizData' to 'viewData' (as in v3)... a much
better name IMHO :-)
And I *totally* agree with you, as this data is exclusively prepared for
and consumed by the view!
Sylvain
--
Sylvain WallezAnyware Technologies
http://apache.org/~sylvainhttp://anyware-tech.com
Apache Software Foundation Member Research & Technology Director
Re: v2 (was Re: [CForms binding] access to model data from repeater row widget)
On Jun 21, 2005, at 8:41 AM, Mark Lundquist wrote:
On Jun 20, 2005, at 11:42 PM, Sylvain Wallez wrote:
BTW, why do you prefer v2 rather than v1?
<..schnip!..>
One thing I don't care so much for in v2 is the idiom of attaching view
data as properties of the widget tree root. The minimalist approach
(losing 'bizData') was clever, but in actual practice I find that I
really like having one locus of transfer of data between the flowscript
and the presentation, so I usually end up with something like this
anyway:
w.viewData =
{
schtuff: foobar,
etc:otherStuff
};
form.showForm ('whatev');
...and so I guess I'd rather have it as an explicit parameter (and also
not needing to have 'viewData.' at the head of the expression path
within the JX template).
While on the subject... since I am "Mr. Anal Nomenclature Pants", I
would vote for changing 'bizData' to 'viewData' (as in v3)... a much
better name IMHO :-)
cheers,
—ml—
Re: [CForms binding] access to model data from repeater row widget
Mark Lundquist wrote: On Jun 20, 2005, at 11:42 PM, Sylvain Wallez wrote: So in essence, you want to act on the selected rows, right? Yup. I encountered this already, and I've been thinking to explicitely add the selection concept to repeaters. That selection would be defined by a boolean field present on each row. Great idea. That is orthogonal to what I've done... you are saying "selection is an intrinsic aspect of rows", and I'm saying "I need a handle on the data". Yeah, right :-) Note that a boolean field doesn't necessarily means rendering as a checkbox. It can also be some highlighting of selected rows. Yup. That would lead to Repeater actions such as "delete-rows" would then no more have a need to be given the select widget's name as of today. +1 And even more, repeater actions could have constraints on the selection size, such as single-selection, multiple-selection, leading these actions to be disabled if their associated constraint isn't met. ...or a validation error. Like the classic "you must choose at least one" constraint. Not sure this is a validation error. In the case of actions this should be more a transient message (e.g. a popup). That isn't persisted across successive posts of a form. Now we may consider that actions have a special way of handling validation errors by clearing them at each readFromRequest() which is different from other widget types. And finally, we may be able to specify on repeater bindings if they have to act on the whole repeater on just on the selection. Not sure what you mean, can you give an example? The idea is to specify in the binding if it should operate on the full repeater or only on the selected rows. Something like: However... I realized that I have a nomenclature clash with my choice of the name "model". I've been using the v2 API for a long time, so I forgot in v1, there is a Form.model property that denotes the widget value tree. The "model" property is only available on the toplevel form JS object, so there may not be a clash. It's not a hard "name clash", but it is a nomenclature clash in that it's a different sense of the term "model". My new row "model" property is truly the "model", as in "MVC" or as in "loadFormFromModel()". The v1 "model" is "model" in terms of "formmodel", I guess. I just think it's too confusing to have both senses. I actually sort of wish the v1 "model" were called something else, because it isn't the model /a la/ MVC. You're right. The "form.model" is actually the value tree. BTW, why do you prefer v2 rather than v1? So I don't want to cause confusion with another sense of "model"... it should be called something else. "rowData"? "rowObject"? WDYT? It doesn't seem good to me to provide at the API level a way to link the form to the data model, No, no, it /is/ good... :-) as this is something that isn't suitable for all situations (think transactional systems, heavyweight objects, etc). OK, for what percentage of real-life applications would you say it is unsuitable? If it's 10-20%, then do we want to penalize the other 80-90%? I don't deny those situations exist, but I think they are less common, and in those cases my instinct would be to use a DTO at some level instead of binding directly to the model object. My instinct would not be to say, "ah, now /here/ is why we don't provide a handle from repeater rows to their bound data!" :-) One thing I've found to work really well is to build an /ad hoc/ DTO right in the flowscript as a javascript object, which looks to the binding framework just like a Java bean. Another way to say it: adding this repeater row decoration doesn't break any isolation between layers of the application. It breaks an undesirable isolation within a single layer (the form definition, binding and flowscript all live in the UI layer). The degree of isolation between the UI layer and the model, in turn, depends on what is given to the UI layer. If that is a live model object, then the isolation is already broken, and that may or may not be a bad thing, but that concern doesn't belong to the internal architecture of CForms (IMHO... just trying to state a case here :-). This is making me think of a discussion in "Hibernate in Action"... In the chapter "Writing Layered Applications", there's a section entitled "Rethinking DTOs". The authors make the case that the dogma "you should never have live model objects in the view layer" is extreme (maybe it is "quaint and outmoded", like someone in the butthead government of my country has said about the Geneva convention :-/). Anyway... it's not quite what we're talking about here, but it's related. And one of the big strengths of CForms is its strong isolation with the dat
v2 (was Re: [CForms binding] access to model data from repeater row widget)
On Jun 20, 2005, at 11:42 PM, Sylvain Wallez wrote: BTW, why do you prefer v2 rather than v1? Honestly I can't remember ATM... :-) I switched a long time ago because (a) I was under the impression that v2 was where the form API was headed, and (b) more importantly, there were specific things that I could do in v2 and not in v1. I think the the clincher had to do with actions, and being able to access something or other from within the action callback, or something. Like I said, I switched long enough ago that I can't remember now in terms of "can't do that in v1" things. I'm actually using a custom extension to Form that encapsulates a standard usage model that I've settled on, mostly naming and locations of things. And I based that on v2, so for the time being I've stuck myself with it :-) —ml—
Re: [CForms binding] access to model data from repeater row widget
On Jun 20, 2005, at 11:42 PM, Sylvain Wallez wrote: So in essence, you want to act on the selected rows, right? Yup. I encountered this already, and I've been thinking to explicitely add the selection concept to repeaters. That selection would be defined by a boolean field present on each row. Great idea. That is orthogonal to what I've done... you are saying "selection is an intrinsic aspect of rows", and I'm saying "I need a handle on the data". Note that a boolean field doesn't necessarily means rendering as a checkbox. It can also be some highlighting of selected rows. Yup. That would lead to Repeater actions such as "delete-rows" would then no more have a need to be given the select widget's name as of today. +1 And even more, repeater actions could have constraints on the selection size, such as single-selection, multiple-selection, leading these actions to be disabled if their associated constraint isn't met. ...or a validation error. Like the classic "you must choose at least one" constraint. And finally, we may be able to specify on repeater bindings if they have to act on the whole repeater on just on the selection. Not sure what you mean, can you give an example? However... I realized that I have a nomenclature clash with my choice of the name "model". I've been using the v2 API for a long time, so I forgot in v1, there is a Form.model property that denotes the widget value tree. The "model" property is only available on the toplevel form JS object, so there may not be a clash. It's not a hard "name clash", but it is a nomenclature clash in that it's a different sense of the term "model". My new row "model" property is truly the "model", as in "MVC" or as in "loadFormFromModel()". The v1 "model" is "model" in terms of "formmodel", I guess. I just think it's too confusing to have both senses. I actually sort of wish the v1 "model" were called something else, because it isn't the model a la MVC. BTW, why do you prefer v2 rather than v1? So I don't want to cause confusion with another sense of "model"... it should be called something else. "rowData"? "rowObject"? WDYT? It doesn't seem good to me to provide at the API level a way to link the form to the data model, No, no, it is good... :-) as this is something that isn't suitable for all situations (think transactional systems, heavyweight objects, etc). OK, for what percentage of real-life applications would you say it is unsuitable? If it's 10-20%, then do we want to penalize the other 80-90%? I don't deny those situations exist, but I think they are less common, and in those cases my instinct would be to use a DTO at some level instead of binding directly to the model object. My instinct would not be to say, "ah, now here is why we don't provide a handle from repeater rows to their bound data!" :-) One thing I've found to work really well is to build an ad hoc DTO right in the flowscript as a javascript object, which looks to the binding framework just like a Java bean. Another way to say it: adding this repeater row decoration doesn't break any isolation between layers of the application. It breaks an undesirable isolation within a single layer (the form definition, binding and flowscript all live in the UI layer). The degree of isolation between the UI layer and the model, in turn, depends on what is given to the UI layer. If that is a live model object, then the isolation is already broken, and that may or may not be a bad thing, but that concern doesn't belong to the internal architecture of CForms (IMHO... just trying to state a case here :-). This is making me think of a discussion in "Hibernate in Action"... In the chapter "Writing Layered Applications", there's a section entitled "Rethinking DTOs". The authors make the case that the dogma "you should never have live model objects in the view layer" is extreme (maybe it is "quaint and outmoded", like someone in the butthead government of my country has said about the Geneva convention :-/). Anyway... it's not quite what we're talking about here, but it's related. And one of the big strengths of CForms is its strong isolation with the data model while the user is messing around with input values. Hmm, well you can't modify the data from JXTemplate, or at least the mechanisms are not well-known ;-/ (and maybe JXT is too strong :-)... in any case, I think most people really are interested in using JXT as just a template engine, not in programming in JXT :-). That leaves the flowscript, and you can already have your way with the model data from flowscript if the live data is what the services layer provides... However, there are some uses cases where this makes sense. You can then use widget attributes (see get/setAttribute) to attach some application data of your liking to any widget, including repeater rows. See, that's the problem, this is what I have to deal with currently :-)... I have two parallel structures: a Collection, and a Repeate
Re: [CForms binding] access to model data from repeater row widget
Mark Lundquist wrote:
Hi,
Here is a scenario that I keep finding myself dealing with...
Some repeater is bound to a collection, and also contains one or more
widgets that are /not/ bound to the collection elements. For instance,
there might be a checkbox that means "do something to/with the thing
in this row". After accepting the form, the processing entails
iterating through the rows and doing something something with the
corresponding object from the model layer, which means I need to be
able to find/access that object.
So in essence, you want to act on the selected rows, right? I
encountered this already, and I've been thinking to explicitely add the
selection concept to repeaters. That selection would be defined by a
boolean field present on each row. Note that a boolean field doesn't
necessarily means rendering as a checkbox. It can also be some
highlighting of selected rows.
That would lead to
Repeater actions such as "delete-rows" would then no more have a need to
be given the select widget's name as of today.
And even more, repeater actions could have constraints on the selection
size, such as single-selection, multiple-selection, leading these
actions to be disabled if their associated constraint isn't met.
And finally, we may be able to specify on repeater bindings if they have
to act on the whole repeater on just on the selection.
It seems like each time, I come up with some different way of handling
this, and none of them ever feels quite right.
Then I thought, if the binding framework would decorate each repeater
row widget with a property that references the bound object, things
would just be a lot cleaner.
So I made this trivial change, and it works great. The repeater rows
now have a "model" property that references the model object to which
that row is bound. I tweaked the JXTG macro version of the template
engine so that I can reference "${model_}" from within the
. That is really handy, because it lets me avoid
having to specify a bunch of output widgets in the the form definition
+ binding. What I really had in mind with this change, though, was
making the flowscript easier, and it does do that... but currently in
the flow I have to unwrap() the repeater row widget by hand before I
can call getModel() on it, so before I finalize this I want to add
that to the Form flow API. Then I think it will be just right.
However...
I realized that I have a nomenclature clash with my choice of the name
"model". I've been using the v2 API for a long time, so I forgot in
v1, there is a Form.model property that denotes the widget value tree.
The "model" property is only available on the toplevel form JS object,
so there may not be a clash. BTW, why do you prefer v2 rather than v1?
So I don't want to cause confusion with another sense of "model"... it
should be called something else. "rowData"? "rowObject"? WDYT?
It doesn't seem good to me to provide at the API level a way to link the
form to the data model, as this is something that isn't suitable for all
situations (think transactional systems, heavyweight objects, etc). And
one of the big strengths of CForms is its strong isolation with the data
model while the user is messing around with input values.
However, there are some uses cases where this makes sense. You can then
use widget attributes (see get/setAttribute) to attach some application
data of your liking to any widget, including repeater rows.
You can also have a look at the new Tree widget in trunk. It relies on a
lightweight model to access arbitrarily large hierarchies. And a
repeater is not far from being a tree of depth 1 :-)
Sylvain
--
Sylvain WallezAnyware Technologies
http://apache.org/~sylvainhttp://anyware-tech.com
Apache Software Foundation Member Research & Technology Director
Re: [CForms binding] access to model data from repeater row widget
Mark Lundquist wrote:
Hi,
Here is a scenario that I keep finding myself dealing with...
Some repeater is bound to a collection, and also contains one or more
widgets that are /not/ bound to the collection elements. For instance,
there might be a checkbox that means "do something to/with the thing in
this row". After accepting the form, the processing entails iterating
through the rows and doing something something with the corresponding
object from the model layer, which means I need to be able to
find/access that object.
It seems like each time, I come up with some different way of handling
this, and none of them ever feels quite right.
Then I thought, if the binding framework would decorate each repeater
row widget with a property that references the bound object, things
would just be a lot cleaner.
So I made this trivial change, and it works great. The repeater rows now
have a "model" property that references the model object to which that
row is bound. I tweaked the JXTG macro version of the template engine so
that I can reference "${model_}" from within the .
That is really handy, because it lets me avoid having to specify a bunch
of output widgets in the the form definition + binding. What I really
had in mind with this change, though, was making the flowscript easier,
and it does do that... but currently in the flow I have to unwrap() the
repeater row widget by hand before I can call getModel() on it, so
before I finalize this I want to add that to the Form flow API. Then I
think it will be just right.
However...
I realized that I have a nomenclature clash with my choice of the name
"model". I've been using the v2 API for a long time, so I forgot in v1,
there is a Form.model property that denotes the widget value tree. So I
don't want to cause confusion with another sense of "model"... it should
be called something else. "rowData"? "rowObject"? WDYT?
please advise! :-)
no advice but a link: see
http://marc.theaimsgroup.com/?l=xml-cocoon-dev&m=109950611823830&w=2
--
Reinhard Pötz Independent Consultant, Trainer & (IT)-Coach
{Software Engineering, Open Source, Web Applications, Apache Cocoon}
web(log): http://www.poetz.cc
[CForms binding] access to model data from repeater row widget
Hi,
Here is a scenario that I keep finding myself dealing with...
Some repeater is bound to a collection, and also contains one or more widgets that are not bound to the collection elements. For instance, there might be a checkbox that means "do something to/with the thing in this row". After accepting the form, the processing entails iterating through the rows and doing something something with the corresponding object from the model layer, which means I need to be able to find/access that object.
It seems like each time, I come up with some different way of handling this, and none of them ever feels quite right.
Then I thought, if the binding framework would decorate each repeater row widget with a property that references the bound object, things would just be a lot cleaner.
So I made this trivial change, and it works great. The repeater rows now have a "model" property that references the model object to which that row is bound. I tweaked the JXTG macro version of the template engine so that I can reference "${model_}" from within the . That is really handy, because it lets me avoid having to specify a bunch of output widgets in the the form definition + binding. What I really had in mind with this change, though, was making the flowscript easier, and it does do that... but currently in the flow I have to unwrap() the repeater row widget by hand before I can call getModel() on it, so before I finalize this I want to add that to the Form flow API. Then I think it will be just right.
However...
I realized that I have a nomenclature clash with my choice of the name "model". I've been using the v2 API for a long time, so I forgot in v1, there is a Form.model property that denotes the widget value tree. So I don't want to cause confusion with another sense of "model"... it should be called something else. "rowData"? "rowObject"? WDYT?
please advise! :-)
—ml—
