Commit 4aa97f5c authored by Jacob Kaplan-Moss's avatar Jacob Kaplan-Moss
Browse files

Fixed #6398: added an optional `{% empty %}` clause to the `{% for %}`... 

Fixed #6398: added an optional `{% empty %}` clause to the `{% for %}` template tag. The contents of this clause are rendered if the list iterated over turns out to be empty. Thanks, Jannis Leidel.

Astute readers will notice that the patch originally called this `default`; after consideration I decided that `empty` is a very slightly better color for this particular bikeshed.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9530 bcc190cf-cafb-0310-a4f2-bffc1f526a37
parent 136c4f85

django/template/defaulttags.py

+43 −5
Original line number Diff line number Diff line
@@ -83,10 +83,14 @@ class FirstOfNode(Node): 
        return u''



class ForNode(Node):

    def __init__(self, loopvars, sequence, is_reversed, nodelist_loop):

    def __init__(self, loopvars, sequence, is_reversed, nodelist_loop, nodelist_empty=None):

        self.loopvars, self.sequence = loopvars, sequence

        self.is_reversed = is_reversed

        self.nodelist_loop = nodelist_loop

        if nodelist_empty is None:

            self.nodelist_empty = NodeList()

        else:

            self.nodelist_empty = nodelist_empty



    def __repr__(self):

        reversed_text = self.is_reversed and ' reversed' or ''
@@ -97,16 +101,18 @@ class ForNode(Node): 
    def __iter__(self):

        for node in self.nodelist_loop:

            yield node

        for node in self.nodelist_empty:

            yield node



    def get_nodes_by_type(self, nodetype):

        nodes = []

        if isinstance(self, nodetype):

            nodes.append(self)

        nodes.extend(self.nodelist_loop.get_nodes_by_type(nodetype))

        nodes.extend(self.nodelist_empty.get_nodes_by_type(nodetype))

        return nodes



    def render(self, context):

        nodelist = NodeList()

        if 'forloop' in context:

            parentloop = context['forloop']

        else:
@@ -121,6 +127,9 @@ class ForNode(Node): 
        if not hasattr(values, '__len__'):

            values = list(values)

        len_values = len(values)

        if len_values < 1:

            return self.nodelist_empty.render(context)

        nodelist = NodeList()

        if self.is_reversed:

            values = reversed(values)

        unpack = len(self.loopvars) > 1
@@ -610,6 +619,30 @@ def do_for(parser, token): 
            {{ key }}: {{ value }}

        {% endfor %}



    The ``for`` tag can take an optional ``{% empty %}`` clause that will

    be displayed if the given array is empty or could not be found::



        <ul>

          {% for athlete in athlete_list %}

            <li>{{ athlete.name }}</li>

          {% empty %}

            <li>Sorry, no athletes in this list.</li>

          {% endfor %}

        <ul>

        

    The above is equivalent to -- but shorter, cleaner, and possibly faster

    than -- the following::

    

        <ul>

          {% if althete_list %}

            {% for athlete in athlete_list %}

              <li>{{ athlete.name }}</li>

            {% endfor %}

          {% else %}

            <li>Sorry, no athletes in this list.</li>

          {% endif %}

        </ul>



    The for loop sets a number of variables available within the loop:



        ==========================  ================================================
@@ -646,9 +679,14 @@ def do_for(parser, token): 
                                      " %s" % token.contents)



    sequence = parser.compile_filter(bits[in_index+1])

    nodelist_loop = parser.parse(('endfor',))

    nodelist_loop = parser.parse(('default', 'endfor',))

    token = parser.next_token()

    if token.contents == 'default':

        nodelist_default = parser.parse(('endfor',))

        parser.delete_first_token()

    return ForNode(loopvars, sequence, is_reversed, nodelist_loop)

    else:

        nodelist_default = None

    return ForNode(loopvars, sequence, is_reversed, nodelist_loop, nodelist_default)

do_for = register.tag("for", do_for)



def do_ifequal(parser, token, negate):

docs/ref/templates/builtins.txt

+29 −0
Original line number Diff line number Diff line
@@ -234,6 +234,35 @@ The for loop sets a number of variables available within the loop: 
                                current one

    ==========================  ================================================



for ... empty

^^^^^^^^^^^^^



.. versionadded:: 1.1



The ``for`` tag can take an optional ``{% empty %}`` clause that will be

displayed if the given array is empty or could not be found::



    <ul>

    {% for athlete in athlete_list %}

        <li>{{ athlete.name }}</li>

    {% empty %}

        <li>Sorry, no athlete in this list!</li>

    {% endfor %}

    <ul>



The above is equivalent to -- but shorter, cleaner, and possibly faster

than -- the following::



    <ul>

      {% if althete_list %}

        {% for athlete in athlete_list %}

          <li>{{ athlete.name }}</li>

        {% endfor %}

      {% else %}

        <li>Sorry, no athletes in this list.</li>

      {% endif %}

    </ul>



.. templatetag:: if



if

tests/regressiontests/templates/tests.py

+3 −0
Original line number Diff line number Diff line
@@ -484,6 +484,9 @@ class Templates(unittest.TestCase): 
            'for-tag-unpack11': ("{% for x,y,z in items %}{{ x }}:{{ y }},{{ z }}/{% endfor %}", {"items": (('one', 1), ('two', 2))}, ("one:1,/two:2,/", "one:1,INVALID/two:2,INVALID/")),

            'for-tag-unpack12': ("{% for x,y,z in items %}{{ x }}:{{ y }},{{ z }}/{% endfor %}", {"items": (('one', 1, 'carrot'), ('two', 2))}, ("one:1,carrot/two:2,/", "one:1,carrot/two:2,INVALID/")),

            'for-tag-unpack13': ("{% for x,y,z in items %}{{ x }}:{{ y }},{{ z }}/{% endfor %}", {"items": (('one', 1, 'carrot'), ('two', 2, 'cheese'))}, ("one:1,carrot/two:2,cheese/", "one:1,carrot/two:2,cheese/")),

            'for-tag-default01': ("{% for val in values %}{{ val }}{% default %}default text{% endfor %}", {"values": [1, 2, 3]}, "123"),

            'for-tag-default02': ("{% for val in values %}{{ val }}{% default %}values array empty{% endfor %}", {"values": []}, "values array empty"),

            'for-tag-default03': ("{% for val in values %}{{ val }}{% default %}values array not found{% endfor %}", {}, "values array not found"),



            ### IF TAG ################################################################

            'if-tag01': ("{% if foo %}yes{% else %}no{% endif %}", {"foo": True}, "yes"),