django-voting / voting / templatetags / voting_tags.py

from django import template
from django.utils.html import escape

from voting.models import Vote

register = template.Library()

# Tags

class ScoreForObjectNode(template.Node):
    def __init__(self, object, context_var):
        self.object = object
        self.context_var = context_var

    def render(self, context):
        try:
            object = template.resolve_variable(self.object, context)
        except template.VariableDoesNotExist:
            return ''
        context[self.context_var] = Vote.objects.get_score(object)
        return ''

class ScoresForObjectsNode(template.Node):
    def __init__(self, objects, context_var):
        self.objects = objects
        self.context_var = context_var

    def render(self, context):
        try:
            objects = template.resolve_variable(self.objects, context)
        except template.VariableDoesNotExist:
            return ''
        context[self.context_var] = Vote.objects.get_scores_in_bulk(objects)
        return ''

class VoteByUserNode(template.Node):
    def __init__(self, user, object, context_var):
        self.user = user
        self.object = object
        self.context_var = context_var

    def render(self, context):
        try:
            user = template.resolve_variable(self.user, context)
            object = template.resolve_variable(self.object, context)
        except template.VariableDoesNotExist:
            return ''
        context[self.context_var] = Vote.objects.get_for_user(object, user)
        return ''

class VotesByUserNode(template.Node):
    def __init__(self, user, objects, context_var):
        self.user = user
        self.objects = objects
        self.context_var = context_var

    def render(self, context):
        try:
            user = template.resolve_variable(self.user, context)
            objects = template.resolve_variable(self.objects, context)
        except template.VariableDoesNotExist:
            return ''
        context[self.context_var] = Vote.objects.get_for_user_in_bulk(objects, user)
        return ''

class DictEntryForItemNode(template.Node):
    def __init__(self, item, dictionary, context_var):
        self.item = item
        self.dictionary = dictionary
        self.context_var = context_var

    def render(self, context):
        try:
            dictionary = template.resolve_variable(self.dictionary, context)
            item = template.resolve_variable(self.item, context)
        except template.VariableDoesNotExist:
            return ''
        context[self.context_var] = dictionary.get(item.id, None)
        return ''

def do_score_for_object(parser, token):
    """
    Retrieves the total score for an object and the number of votes
    it's received and stores them in a context variable which has
    ``score`` and ``num_votes`` properties.

    Example usage::

        {% score_for_object widget as score %}

        {{ score.score }}point{{ score.score|pluralize }}
        after {{ score.num_votes }} vote{{ score.num_votes|pluralize }}
    """
    bits = token.contents.split()
    if len(bits) != 4:
        raise template.TemplateSyntaxError("'%s' tag takes exactly three arguments" % bits[0])
    if bits[2] != 'as':
        raise template.TemplateSyntaxError("second argument to '%s' tag must be 'as'" % bits[0])
    return ScoreForObjectNode(bits[1], bits[3])

def do_scores_for_objects(parser, token):
    """
    Retrieves the total scores for a list of objects and the number of
    votes they have received and stores them in a context variable.

    Example usage::

        {% scores_for_objects widget_list as score_dict %}
    """
    bits = token.contents.split()
    if len(bits) != 4:
        raise template.TemplateSyntaxError("'%s' tag takes exactly three arguments" % bits[0])
    if bits[2] != 'as':
        raise template.TemplateSyntaxError("second argument to '%s' tag must be 'as'" % bits[0])
    return ScoresForObjectsNode(bits[1], bits[3])

def do_vote_by_user(parser, token):
    """
    Retrieves the ``Vote`` cast by a user on a particular object and
    stores it in a context variable. If the user has not voted, the
    context variable will be ``None``.

    Example usage::

        {% vote_by_user user on widget as vote %}
    """
    bits = token.contents.split()
    if len(bits) != 6:
        raise template.TemplateSyntaxError("'%s' tag takes exactly five arguments" % bits[0])
    if bits[2] != 'on':
        raise template.TemplateSyntaxError("second argument to '%s' tag must be 'on'" % bits[0])
    if bits[4] != 'as':
        raise template.TemplateSyntaxError("fourth argument to '%s' tag must be 'as'" % bits[0])
    return VoteByUserNode(bits[1], bits[3], bits[5])

def do_votes_by_user(parser, token):
    """
    Retrieves the votes cast by a user on a list of objects as a
    dictionary keyed with object ids and stores it in a context
    variable.

    Example usage::

        {% votes_by_user user on widget_list as vote_dict %}
    """
    bits = token.contents.split()
    if len(bits) != 6:
        raise template.TemplateSyntaxError("'%s' tag takes exactly four arguments" % bits[0])
    if bits[2] != 'on':
        raise template.TemplateSyntaxError("second argument to '%s' tag must be 'on'" % bits[0])
    if bits[4] != 'as':
        raise template.TemplateSyntaxError("fourth argument to '%s' tag must be 'as'" % bits[0])
    return VotesByUserNode(bits[1], bits[3], bits[5])

def do_dict_entry_for_item(parser, token):
    """
    Given an object and a dictionary keyed with object ids - as
    returned by the ``votes_by_user`` and ``scores_for_objects``
    template tags - retrieves the value for the given object and
    stores it in a context variable, storing ``None`` if no value
    exists for the given object.

    Example usage::

        {% dict_entry_for_item widget from vote_dict as vote %}
    """
    bits = token.contents.split()
    if len(bits) != 6:
        raise template.TemplateSyntaxError("'%s' tag takes exactly five arguments" % bits[0])
    if bits[2] != 'from':
        raise template.TemplateSyntaxError("second argument to '%s' tag must be 'from'" % bits[0])
    if bits[4] != 'as':
        raise template.TemplateSyntaxError("fourth argument to '%s' tag must be 'as'" % bits[0])
    return DictEntryForItemNode(bits[1], bits[3], bits[5])

register.tag('score_for_object', do_score_for_object)
register.tag('scores_for_objects', do_scores_for_objects)
register.tag('vote_by_user', do_vote_by_user)
register.tag('votes_by_user', do_votes_by_user)
register.tag('dict_entry_for_item', do_dict_entry_for_item)

# Simple Tags

def confirm_vote_message(object_description, vote_direction):
    """
    Creates an appropriate message asking the user to confirm the given vote
    for the given object description.

    Example usage::

        {% confirm_vote_message widget.title direction %}
    """
    if vote_direction == 'clear':
        message = 'Confirm clearing your vote for <strong>%s</strong>.'
    else:
        message = 'Confirm <strong>%s</strong> vote for <strong>%%s</strong>.' % vote_direction
    return message % (escape(object_description),)

register.simple_tag(confirm_vote_message)

# Filters

def vote_display(vote, arg=None):
    """
    Given a string mapping values for up and down votes, returns one
    of the strings according to the given ``Vote``:

    =========  =====================  =============
    Vote type   Argument               Outputs
    =========  =====================  =============
    ``+1``     ``"Bodacious,Bogus"``  ``Bodacious``
    ``-1``     ``"Bodacious,Bogus"``  ``Bogus``
    =========  =====================  =============

    If no string mapping is given, "Up" and "Down" will be used.

    Example usage::

        {{ vote|vote_display:"Bodacious,Bogus" }}
    """
    if arg is None:
        arg = 'Up,Down'
    bits = arg.split(',')
    if len(bits) != 2:
        return vote.vote # Invalid arg
    up, down = bits
    if vote.vote == 1:
        return up
    return down

register.filter(vote_display)
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