Hi all,
When using batching in dtml-in, why is 'previous-sequence' only defined at
the first iteration of the current batch? And why is 'next-sequence' only
defined at the last iteration of the current batch?
This behaviour makes it difficult to display a batch like this:
-- begin sample --
Item N
Item N+1
Item N+2
(link to previous items) (link to next items)
-- end sample --
Because the code would be something like:
-- begin sample --
<dtml-in something start=query_start size=3>
[do something with sequence-item]
<dtml-if sequence-end> <!-- check if last item of batch -->
<dtml-if previous-sequence>
(link to previous items)
</dtml-if>
<dtml-if next-sequence>
(link to next items)
</dtml-if>
</dtml-if>
</dtml-in>
-- end sample --
However, if your batchsize is larger than 1, 'previous-sequence' will always
be untrue at the last item (when sequence-item is true).
The only solution would be implement a second dtml-in after the first one
purely for displaying the previous link.
Also, dtml-in would re-execute your "expr" (which it does not very efficiently),
so if you want to avoid doing the "expr" twice, you'd have to store it
temporarily using dtml-let (or my dtml-set tag ;).
The end result would be:
-- start sample --
<dtml-let foo="expr">
<dtml-in foo start=start_query size=3>
[do something with sequence-item]
</dtml-in>
<dtml-in foo start=start_query size=3>
<!-- code below is safe, as the variables are only true at the resp. top and
end, though the truly paranoid could check for sequence-start / -end
patch #1 below would break such code!
-->
<dtml-if sequence-end>
<dtml-if previous-sequence>
(link to previous items)
</dtml-if>
<dtml-if next-sequence>
(link to next items)
</dtml-if>
</dtml-if>
</dtml-in>
</dtml-let>
-- end sample --
And at this point I really would start to implement the batching myself in
python :)
Of course, basically the same applies if you want both the previous/next link
at the top of the batch display.
(Imagine you want both! :)
Either I'm missing something really obvious here, or the patches below make
sense. There are two versions:
- patch #1: This version fixes the issue above by enabling the values of
previous/next-sequence throughout the entire batch (and other
related variables as well: X-sequence, X-sequence-start-index,
X-sequence-end-index, X-sequence-size) (which may break existing sites), and
- patch #2: This version introduces new variablenames, leaving the behaviour of
previous/next-sequence.
A third alternative would be to only define the variables at the top and
bottom of the batch.
Both versions fix (I think) a grammatical error.
It's up to the DC guys if they feel like incorporating either of these patches
in a next release :)
patch #1: define variables everywhere in the batch
This patch makes sure that the following variables are available through
each iteration of dtml-in, for each item.
!!!!! This patch may break alot of dtml code !!!!!!
next-sequence
next-sequence-start-index
next-sequence-end-index
next-sequence-size
previous-sequence
previous-sequence-start-index
previous-sequence-end-index
previous-sequence-size
-- patch begins here --
*** Zope-2.3.2-orig/lib/python/DocumentTemplate/DT_In.py Fri Apr 13 21:30:38
2001
--- Zope-2.3.2-src/lib/python/DocumentTemplate/DT_In.py Tue May 29 19:52:36
2001***************
*** 583,611 ****
for index in range(first,end):
# preset
kw['previous-sequence']= 0
! kw['next-sequence']= 0 # now more often defined then previously
#
! if index==first or index==last:
! # provide batching information
! if first > 0:
! pstart,pend,psize=opt(0,first+overlap,
! sz,orphan,sequence)
! if index==first: kw['previous-sequence']=1
! kw['previous-sequence-start-index']=pstart-1
! kw['previous-sequence-end-index']=pend-1
! kw['previous-sequence-size']=pend+1-pstart
! try:
! # The following line is a sneaky way to
! # test whether there are more items,
! # without actually computing a length:
! sequence[end]
! pstart,pend,psize=opt(end+1-overlap,0,
! sz,orphan,sequence)
! if index==last: kw['next-sequence']=1
! kw['next-sequence-start-index']=pstart-1
! kw['next-sequence-end-index']=pend-1
! kw['next-sequence-size']=pend+1-pstart
! except: pass
if index==last: kw['sequence-end']=1
--- 583,610 ----
for index in range(first,end):
# preset
kw['previous-sequence']= 0
! kw['next-sequence']= 0 # now more often defined than previously
#
! # provide batching information
! if first > 0:
! pstart,pend,psize=opt(0,first+overlap,
! sz,orphan,sequence)
! kw['previous-sequence']=1
! kw['previous-sequence-start-index']=pstart-1
! kw['previous-sequence-end-index']=pend-1
! kw['previous-sequence-size']=pend+1-pstart
! try:
! # The following line is a sneaky way to
! # test whether there are more items,
! # without actually computing a length:
! sequence[end]
! pstart,pend,psize=opt(end+1-overlap,0,
! sz,orphan,sequence)
! kw['next-sequence']=1
! kw['next-sequence-start-index']=pstart-1
! kw['next-sequence-end-index']=pend-1
! kw['next-sequence-size']=pend+1-pstart
! except: pass
if index==last: kw['sequence-end']=1
-- end --
patch #2: introduce new variables
This patch introduces the variables
batch-next-sequence
batch-next-sequence-start-index
batch-next-sequence-end-index
batch-next-sequence-size
batch-previous-sequence
batch-previous-sequence-start-index
batch-previous-sequence-end-index
batch-previous-sequence-size
Which behave exactly the same as the variables withouth 'batch-' in front,
but these are available with each iteration/item of dtml-in, not just the
first/last. This patch should not break any existing dtml code.
-- patch begins here --
*** Zope-2.3.2-orig/lib/python/DocumentTemplate/DT_In.py Fri Apr 13 21:30:38
2001
--- Zope-2.3.2-src/lib/python/DocumentTemplate/DT_In.py Tue May 29 20:23:24 2001
***************
*** 583,589 ****
for index in range(first,end):
# preset
kw['previous-sequence']= 0
! kw['next-sequence']= 0 # now more often defined then previously
#
if index==first or index==last:
# provide batching information
--- 583,609 ----
for index in range(first,end):
# preset
kw['previous-sequence']= 0
! kw['next-sequence']= 0 # now more often defined than previously
! # provide batching information
! if first > 0:
! pstart,pend,psize=opt(0,first+overlap,
! sz,orphan,sequence)
! kw['batch-previous-sequence']=1
! kw['batch-previous-sequence-start-index']=pstart-1
! kw['batch-previous-sequence-end-index']=pend-1
! kw['batch-previous-sequence-size']=pend+1-pstart
! try:
! # The following line is a sneaky way to
! # test whether there are more items,
! # without actually computing a length:
! sequence[end]
! pstart,pend,psize=opt(end+1-overlap,0,
! sz,orphan,sequence)
! kw['batch-next-sequence']=1
! kw['batch-next-sequence-start-index']=pstart-1
! kw['batch-next-sequence-end-index']=pend-1
! kw['batch-next-sequence-size']=pend+1-pstart
! except: pass
#
if index==first or index==last:
# provide batching information
--
To apply either of them, cd to your SOFTWARE_HOME (i.e. Zope-2.3.2-src)
and patch -p1 < /location/of/patch
NOTE! It only makes sense to apply one of these patches, not both!
Cheers,
Ivo
--
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Brouwersgracht 132 Amaze Internet Services V.O.F.
1013 HA Amsterdam -=-
Tel: +31-20-4688336 Linux/Web/Zope/SQL
Fax: +31-20-4688337 Network Solutions
Web: http://www.amaze.nl/ Consultancy
Email: [EMAIL PROTECTED] -=-
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