11 Jul
2011
11 Jul
'11
3:06 p.m.
Hi devs,
I'd like to make the following proposal based on your feedback:
(1) a sheet is a document that has an object of type XWiki.SheetClass
(2) the sheet code is stored in the sheet document content
(3) XWiki.SheetClass has the following properties:
display: Static List ('page', 'inline', 'meta')
action: String ('view', 'edit', etc.)
The 'display' property specifies where to place the sheet output:
* page: the sheet output overwrites the 'mainContentArea', 'xdocFooter'
and 'xwikidata' DIVs. This means everything besides the header (logo and
top menu), the content menu, the footer (version and license info) and
the side columns (panels).
* inline: the sheet output overwrites the content of the 'xwikicontent'
DIV in view mode and the form fields in edit mode (similar to the
current inline edit mode).
* meta: the sheet output is aggregated under the "Objects" document
extra tab. The bottom tabs are displayed only in view mode currently but
we can imagine ways to display 'meta' sheets in edit mode too.
The 'action' property specifies when to apply the sheet. The empty
string means the sheet can be applied on any action.
(4) Sheets can control the UI elements outside of their scope through
parameters, depending on the value of the display property:
* page: since sheets of this type control most of what is displayed the
only useful parameter is the list of left/right panels.
* inline: list of left/right panels, show/hide breadcrumb, show/hide
title, show/hide bottom tabs, list of bottom tabs, show/hide version
summary in edit mode.
* meta: no parameters because sheets of this type are used to display
secondary objects.
Now, regarding the way to set these parameters I think we have three
options:
(4A) String parameters
Use a generic class, XWiki.ParameterClass, with two string properties,
key and value.
pro: we can easily add a new parameter to the sheet (by adding a new
parameter object to the sheet document) without modifying the parameters
class.
con: error prone
(4B) Typed parameters
Use a specific class, XWiki.SheetConfigClass, with properties matching
configuration parameters.
pro: less error prone since parameters are typed and their names are
hard-coded
con: harder to add/remove/rename parameters
(4C) Velocity parameters
Add a TextArea property to the XWiki.SheetClass, called 'parameters',
where we can set velocity variables. The value of this property will be
evaluated in startpage.vm after xwikivars.vm and layoutvars.vm.
I prefer (4C).
(5) In order to declare a sheet a xclass (or a plain document) has to
use an object of type XWiki.SheetInclude that has only one Database list
property called 'sheet' which, obviously, specifies the sheet to be
applied. A xclass can include zero (no sheets) or more sheets (a
different sheet for a different action).
(6) The only case when sheets can conflict is when a document has
objects of different types that declare 'page' sheets for the same
action. Multiple objects with 'meta' sheets are aggregated under the
'Objects' tab. Multiple objects with 'inline' sheets are aggregated
inside the 'xwikicontent' element in view mode and inside the same HTML
form in edit mode. A 'page' sheet can choose to display 'inline' and
'meta' sheets, and of course 'inline' and 'meta' sheets can be
displayed
by the default view mode.
The conflict between 'page' sheets can be resolved by defining an order
between objects. I prefer an inherent order (e.g. the object that was
added first is the most/less important) rather than an explicit priority
field.
(7) Sheet resolution:
* if the current document has an object of type XWiki.SheetInclude and
the specified sheet has display:page and matches the current action then
apply it (in case there are more XWiki.SheetInclude objects that satisfy
this constraint then use the one with the lowest/highest index).
* if the current document has objects whose xclass declares a 'page'
sheet, then resolve the conflict and use the proper sheet.
* if there is no 'page' sheet included either by the current document or
by one of its objects then aggregate all 'inline' and 'meta' sheets
(from the objects and from the document itself).
* if there are no 'inline' sheets then simply display the default
view/edit mode.
WDYT?
Thanks,
Marius
On 06/28/2011 07:43 PM, Marius Dumitru Florea wrote:
Hi devs,
A prerequisite for Application Within Minutes [1] is to be able to
specify the sheet that will be used to display a document without
touching the content of that document [2]. This can be done in multiple
ways, depending on how we define the notion of a sheet.
(1) Class sheets vs. document sheets
A class sheet displays an object of a particular type and is specified
in the definition of that type. This means that when you create or edit
a class, i.e. a type of object, you can specify which sheet should be
used to display the instances of that class.
Pro: Documents don't have to specify a sheet.
Con: We have to determine which sheet to use in case there are multiple
objects attached to a document.
A document sheet displays a document of a particular type and is
specified at document level because the document type, unlike the
xclass, does not exist actually. The document type is inferred from the
type of objects the document has, or from its content, or, why not, from
the type of attachments it has.
Pro: Doesn't have the class sheet con.
Con: Each document has to specify which sheet to use.
Class sheets are enough for Application Within Minutes because the
wizard will create a single class (with a sheet) and so the application
items will have only one object that specifies a sheet.
(2) Separate sheets per action?
The current practice is to define a single (class) sheet which either
checks for the current action in its code or uses doc.display method
whose output is action specific.
How often did you had the need to write separate sheets per action (e.g.
create, view, edit, search, changes)?
(3) Which actions require a sheet?
If we're talking about class sheets then the list of actions that target
an object and which require a sheet is limited. Currently we have "view"
and "edit", but Ludovic proposed also "create", "search"
and "changes".
If we're talking about document sheets then we can have custom actions
and so we need an extensible mechanism to map actions to sheets.
(4) Sheet parameters?
If we're talking about class sheets then they only need to specify how
an object is displayed. Document sheets on the other hand may need to
control elements like:
* which tabs (comments, annotations, attachments, etc.), if any, are
displayed
* show title field in edit mode
* the side panels
* the form buttons
WDYT?
Thanks,
Marius
[1] http://dev.xwiki.org/xwiki/bin/view/Design/ApplicationWithinMinutes
[2]
http://dev.xwiki.org/xwiki/bin/view/Design/ApplicationWithinMinutesCoreChan…