> I have a model like
>
> class Task(models.Model):
> name = Models.CharField(max_length = 100)
> parent = models.ForeignKey('Task', null = True)
>
> Using this model say I have got a table like,
>
> Task
> -------
> ID Name Parent_id
> 1 Foo null
> 2 Bar 1
> 3 Baz 1
> 4 Bax 2
>
> I want to display this information hierchically in the template,
> something like
>
> <ul>
> <li> Foo </li>
> <ul>
> <li> Bar</li>
> <ul><li> Bax </li></ul>
> <li> Baz </li>
> </ul>
> </ul>
>
> Essentially I want to convert a relational data to monarchical data.
> Does any body have snippets/recipe to do something similar? I am using
> mySQL
Shabda, does the piece of code below help? Your problem is very
similar to what I just have tried to do. In my case, for a threaded
forum display.
I've created a class ThreadList, which creates ThreadListItems one by
one. You then create a ThreadList object on a QuerySet, and step
through it in your template.
Let me know if it's useful, and suggestions for improvements if you
use it (one thing I'm thinking of, is allowing the user to specify
the "<li><ul>" and "</ul></li>" tags; could be <div>s, for example).
And I could certainly use a better solution for iterating through the
query_set (this is where my last question came from: http://
groups.google.com/group/django-users/browse_thread/thread/
15c236dedb08b4c4/cf6464805af429ff?hl=en#cf6464805af429ff
Evert
Class definitions all the way at the bottom.
Somewhere in your views.py:
responseDict['thread'] = ThreadList(Task.objects.all()) # filter
as you like; you can use Paginator objects as well, as long as the
result a QuerySet (actually, a list might also work)
Somewhere in your template:
{% if thread %}
<ul class="thread">
{% for t in thread %}
{{ t.step }}
<li>
{{ t.name }}
</li>
{% endfor %}
{{ thread.final }}
</ul>
{% endif %}
The if-clause isn't really necessary, just to prevent an empty <ul></
ul>.
The t.step method steps you 'inwards' or 'outwards', depending on the
level.
The thread.final is necessary to trace backwards enough, so that you
close all <ul> levels
The class definitions:
class ThreadListItem(object):
def __init__(self, item, depth):
self._item = item
self.depth = depth
def step(self):
if self.depth > 0:
return mark_safe(u'<li><ul>' * self.depth)
else:
return mark_safe(u'</ul></li>' * abs(self.depth))
def item(self):
return self._item
def __unicode__(self):
return self.thread_in() + unicode(self.item()) +
self.thread_out()
class ThreadList(object):
def __init__(self, query_set, depth='depth', parent='parent'):
# Note: I'm using len() instead of .count(), so the query_set
# gets evaluated. Without evaluation, the query_set indexing
# in next() goes awry
# 'quick note added in proof/email': the 'depth' key could
be used if your model has a
# specific thread-depth parameter. Otherwise, preferably set
to None.
self.query_set = query_set
self.max = len(self.query_set)
self.depth = depth
self.parent = parent
self.reset()
def __iter__(self):
return self
def next(self):
self.i += 1
if self.i >= self.max:
raise StopIteration
else:
item = self.query_set[self.i]
if self.depth and hasattr(item, self.depth):
depth = int(item.__getattribute__(self.depth))
elif self.parent and hasattr(item, self.parent):
depth = 0
p = item.__getattribute__(self.parent)
while p:
depth += 1
p = p.__getattribute__(self.parent)
d = depth - self.current_level
self.current_level = depth
return ThreadListItem(item, d)
def final(self):
return mark_safe(u'</ul></li>' * self.current_level)
def reset(self):
self.i = -1
self.current_level = 0
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