On Mar 18, 11:24 pm, Clemens <clemens.oer...@gmail.com> wrote:
> Thank you for your patience, Marius.
> > Well you can use different RecordMeta implementations if you need to
> > different representation of a record without sequential template
> > change. So no state dependency.
>, b I'm really not trying to be difficultut having multiple RecordMeta
> instances, for which the HTML output seems to be only one of many
> functionalities, seems to be shooting with canons at sparrows. Having
> a toForm functions that takes some template provider as input could be
> one option.

Well this is kinda already in there but it's private :) ... See:

 private def _toForm(inst: BaseRecord, template: NodeSeq): NodeSeq

so to me makes sense to relax it ... to

public def toForm(inst: BaseRecord, template: NodeSeq): NodeSeq

... thanks for reminding me about this :)

> Anyways, I was not even thinking at record level, but rather at field
> level. See below.
> > Well keeping close view representation and backend abstraction makes a
> > lot of sense as it reduces lots of complexity. Having records/mappers
> > that know how to represent themselves in different contexts (DB,
> > xhtml) brings a lot of benefits an simplicity. I admit thought that
> (Btw, by "context" I meant different HTML display contexts.)
> I agree that a field should be able to provide hints about how it
> should be represented, such as max/min length, type, defaults, etc.
> Depending on the logical context within the app I'm working on, a
> record (and thus its fields) can have multiple representations: row in
> a table, complete record as a table, abbreviated record as a table,
> complete form as table, form as row in a table, form with mandatory
> fields only, records have to be printed out as ini-files, etc.
> Unfortunately, it's not me making this stuff up, it's fixed
> requirements.
> At field level, there are also different possible representations. For
> example, I would like to be able to represent a record as a tabular
> form, with every input field being shown with its preferred length. In
> addition to this, I would like to have a different form with a fixed
> with multi-column layout; for this form, no input field must be wider
> than 40 characters. Somehow I have to tell the fields not to make
> themselves wider than 40 characters, and not just use the maximum
> length.
> Again, what it boils down to is the desire to be able to have
> different representations for a single record, and to have different
> possible representations for each field. This while maintaining as
> much encapsulation as possible.

Well for both mapper and record you have the toForm function which is
per field thus allows you to represent the field in any way you like:
your own Node, augment the default node with new attributes etc. And
your implementation can of choose the layout based on your own

> Hence my original idea to have fields provide representation hints
> (eg. "I'd like to be 80 characters wide"), and then have another
> "something" that uses these hints for the actual output, while
> potentially adding additional hints/constrains (eg. "No one get's more
> than 40 characters"), css directives, a little red star in front of
> mandatory fields (based on a rendering hint), .... Depending on how
> the record is being displayed, I would use a different "something",
> and neither the record nor the fields would have to know anything
> about "application context".

Well since you can override the toForm for each field you can add your
own "something" to it.  Thus you can work with necessary abstractions
to make the field "unaware" of the "application context" if that's
what you want but it feels to me that this is an application specific
concern and not a framework one. Personally if I'd need to render a
record/field in different layouts using mapper I'd probably make the
fields aware of the context in which they need to render themselves.
Context is good ! :)

> If I then had a default "something", which renders fields the way they
> are rendered right now, and have the various record fields
> (StringField, etc.) call upon this default "something" whenever their
> toForm-function is called, no one would notice something has changed.
> But I could also call toForm(formRenderer) for non-default rendering.
> > it's quire a paradigm shift from ... say MVC mindset. But let's not
> > get into a "patterns" debate now .. we had plenty of those :)
> Agreed.
> Best,
> Clemens
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