create data tree (including node.id) using django_treebeard

Question

I'm trying to display a directory tree from a a treebeard model. The annotated list method suggested in the treebeard tutorial works fine, but I'd like to include id information in the data tree.

The dump_bulk() has all the info I need, but as a python and django newbie I'm strugglling to find a way to extract the information and display it in the template.

I've thought about switching to javascript, and parsing the json string, but javascript doesn't like the u prefix before the string values. Is there a simple way to avoid the u prefix?

I've also thought about writing a function based on the get_annotated_list() that does include id information. I'm assuming it should be possible to overload the get_annotated_ list so that id information is included, but I'm not too sure how to tackle that either.

Any and all suggestions to help me progress along the learning curve will be appreciated.

score 1 · Answer 1 · answered Mar 25 '14 at 20:50

As you probably know, get_annotated_list() will return an array of tuples, in the form (node, info). info is just a dictionary, so you can iterate over the list, and add any additional key-pairs you like. E.g.,

for node, info in my_annotated_list:
    info['foo'] = node.id

Pass this to your template, and you should be fine.

You can also use a generator. This is from a project I'm working on right now:

def annotated_menu_items(initial_header, menu_items):
    headings = [initial_header]
    for item, info in menu_items:

        yield item, info, item.is_leaf(), headings[-1:][0]

        if info['open']:
            headings.append(item.title)

        for close in info['close']:
            headings.pop()

Here, I'm adding as extra info whether the node in question is a leaf, and pushing the title from the most recently opened node onto a stack so I can access it from deeper levels of the tree.

You say you're new to Python, so you may want to read up on generators. They you materialize the elements of a (potentially infinite) list lazily. In order to use it, you invoke the function which constructs the generator, then you can treat the generator object as an iterable. E.g.,

my_fancy_menus = annotated_menu_items("My Menu", my_annotated_list)

for menu in my_fancy_menus:
    do_stuff(menu)

You can also pass generators to Django templates, where they are treated like lists.

create data tree (including node.id) using django_treebeard

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