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mkrange - create a range() inside a template - variable/filter support for range values

Author:
berserkpi
Posted:
August 14, 2010
Language:
Python
Version:
1.2
Score:
0 (after 0 ratings)

Ok, I just took wolever's snippet at http://djangosnippets.org/snippets/1926/ and added template variable/filter support for range values.

For instance, you could write something like this:

{% mkrange 1 tool_page.paginator.num_pages|add:"1" as page_range %}

I'm just learning python and django, so any advice would be appreciated. 

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# based on: http://www.djangosnippets.org/snippets/1926/
from django.template import Library, Node, TemplateSyntaxError

register = Library()

class RangeNode(Node):
    def __init__(self, parser, range_args, context_name):
        self.template_parser = parser
        self.range_args = range_args
        self.context_name = context_name

    def render(self, context):

        resolved_ranges = []
        for arg in self.range_args:
            compiled_arg = self.template_parser.compile_filter(arg)
            resolved_ranges.append(compiled_arg.resolve(context, ignore_failures=True))
        context[self.context_name] = range(*resolved_ranges)
        return ""
        
@register.tag
def mkrange(parser, token):
    """
    Accepts the same arguments as the 'range' builtin and creates
    a list containing the result of 'range'.
    
    Syntax:
        {% mkrange [start,] stop[, step] as context_name %}

    For example:
        {% mkrange 5 10 2 as some_range %}
        {% for i in some_range %}
          {{ i }}: Something I want to repeat\n
        {% endfor %}
    
    Produces:
        5: Something I want to repeat 
        7: Something I want to repeat 
        9: Something I want to repeat 
    """

    tokens = token.split_contents()
    fnctl = tokens.pop(0)

    def error():
        raise TemplateSyntaxError, "%s accepts the syntax: {%% %s [start,] " +\
                "stop[, step] as context_name %%}, where 'start', 'stop' " +\
                "and 'step' must all be integers." %(fnctl, fnctl)

    range_args = []
    while True:
        if len(tokens) < 2:
            error()

        token = tokens.pop(0)

        if token == "as":
            break

        range_args.append(token)
    
    if len(tokens) != 1:
        error()

    context_name = tokens.pop()

    return RangeNode(parser, range_args, context_name)

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Comments

Ztyx (on January 11, 2013):

Note that the created range can only be used once in Python 3. It will needl to be wrapped in a list() to be reused.

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