Fixed #20709 -- Allowed {% widthratio %} to accept an "as" parameter.

Thanks clay.evil@ for the suggestion.

5 files changed, 47 insertions, 7 deletions

diff --git a/AUTHORS b/AUTHORS
index cec85c093f..215a06235a 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -539,6 +539,7 @@ answer newbie questions, and generally made Django that much better:
     Brenton Simpson <http://theillustratedlife.com>
     Jozko Skrablin <jozko.skrablin@gmail.com>
     Ben Slavin <benjamin.slavin@gmail.com>
+    Jonathan Slenders
     sloonz <simon.lipp@insa-lyon.fr>
     Paul Smith <blinkylights23@gmail.com>
     Steven L. Smith (fvox13) <steven@stevenlsmith.com>
diff --git a/django/template/defaulttags.py b/django/template/defaulttags.py
index 5c9490f749..921a3594cc 100644
--- a/django/template/defaulttags.py
+++ b/django/template/defaulttags.py
@@ -458,10 +458,11 @@ class VerbatimNode(Node):
         return self.content
 
 class WidthRatioNode(Node):
-    def __init__(self, val_expr, max_expr, max_width):
+    def __init__(self, val_expr, max_expr, max_width, asvar=None):
         self.val_expr = val_expr
         self.max_expr = max_expr
         self.max_width = max_width
+        self.asvar = asvar
 
     def render(self, context):
         try:
@@ -480,7 +481,13 @@ class WidthRatioNode(Node):
             return '0'
         except (ValueError, TypeError):
             return ''
-        return str(int(round(ratio)))
+        result = str(int(round(ratio)))
+
+        if self.asvar:
+            context[self.asvar] = result
+            return ''
+        else:
+            return result
 
 class WithNode(Node):
     def __init__(self, var, name, nodelist, extra_context=None):
@@ -1353,20 +1360,34 @@ def widthratio(parser, token):
 
     For example::
 
-        <img src='bar.gif' height='10' width='{% widthratio this_value max_value max_width %}' />
+        <img src="bar.png" alt="Bar"
+             height="10" width="{% widthratio this_value max_value max_width %}" />
 
     If ``this_value`` is 175, ``max_value`` is 200, and ``max_width`` is 100,
     the image in the above example will be 88 pixels wide
     (because 175/200 = .875; .875 * 100 = 87.5 which is rounded up to 88).
+
+    In some cases you might want to capture the result of widthratio in a
+    variable. It can be useful for instance in a blocktrans like this::
+
+        {% widthratio this_value max_value max_width as width %}
+        {% blocktrans %}The width is: {{ width }}{% endblocktrans %}
     """
     bits = token.split_contents()
-    if len(bits) != 4:
-        raise TemplateSyntaxError("widthratio takes three arguments")
-    tag, this_value_expr, max_value_expr, max_width = bits
+    if len(bits) == 4:
+        tag, this_value_expr, max_value_expr, max_width = bits
+        asvar = None
+    elif len(bits) == 6:
+        tag, this_value_expr, max_value_expr, max_width, as_, asvar = bits
+        if as_ != 'as':
+            raise TemplateSyntaxError("Invalid syntax in widthratio tag. Expecting 'as' keyword")
+    else:
+        raise TemplateSyntaxError("widthratio takes at least three arguments")
 
     return WidthRatioNode(parser.compile_filter(this_value_expr),
                           parser.compile_filter(max_value_expr),
-                          parser.compile_filter(max_width))
+                          parser.compile_filter(max_width),
+                          asvar=asvar)
 
 @register.tag('with')
 def do_with(parser, token):
diff --git a/docs/ref/templates/builtins.txt b/docs/ref/templates/builtins.txt
index afb6e4b123..1fadf77d50 100644
--- a/docs/ref/templates/builtins.txt
+++ b/docs/ref/templates/builtins.txt
@@ -1108,6 +1108,14 @@ If ``this_value`` is 175, ``max_value`` is 200, and ``max_width`` is 100, the
 image in the above example will be 88 pixels wide
 (because 175/200 = .875; .875 * 100 = 87.5 which is rounded up to 88).
 
+.. versionchanged:: 1.7
+
+In some cases you might want to capture the result of ``widthratio`` in a
+variable. It can be useful, for instance, in a :ttag:`blocktrans` like this::
+
+    {% widthratio this_value max_value max_width as width %}
+    {% blocktrans %}The width is: {{ width }}{% endblocktrans %}
+
 .. templatetag:: with
 
 with
diff --git a/docs/releases/1.7.txt b/docs/releases/1.7.txt
index f4bbd058d6..6f6efcb3ca 100644
--- a/docs/releases/1.7.txt
+++ b/docs/releases/1.7.txt
@@ -156,6 +156,9 @@ Minor features
   :meth:`~django.contrib.auth.models.User.email_user()` are passed to the
   underlying :meth:`~django.core.mail.send_mail()` call.
 
+* The :ttag:`widthratio` template tag now accepts an "as" parameter to capture
+  the result in a variable.
+
 Backwards incompatible changes in 1.7
 =====================================
 
diff --git a/tests/template_tests/tests.py b/tests/template_tests/tests.py
index aa0283be79..034280f08d 100644
--- a/tests/template_tests/tests.py
+++ b/tests/template_tests/tests.py
@@ -1575,6 +1575,13 @@ class TemplateTests(TransRealMixin, TestCase):
             # Test whitespace in filter argument
             'widthratio15': ('{% load custom %}{% widthratio a|noop:"x y" b 0 %}', {'a':50,'b':100}, '0'),
 
+            # Widthratio with variable assignment
+            'widthratio16': ('{% widthratio a b 100 as variable %}-{{ variable }}-', {'a':50,'b':100}, '-50-'),
+            'widthratio17': ('{% widthratio a b 100 as variable %}-{{ variable }}-', {'a':100,'b':100}, '-100-'),
+
+            'widthratio18': ('{% widthratio a b 100 as %}', { }, template.TemplateSyntaxError),
+            'widthratio19': ('{% widthratio a b 100 not_as variable %}', { }, template.TemplateSyntaxError),
+
             ### WITH TAG ########################################################
             'with01': ('{% with key=dict.key %}{{ key }}{% endwith %}', {'dict': {'key': 50}}, '50'),
             'legacywith01': ('{% with dict.key as key %}{{ key }}{% endwith %}', {'dict': {'key': 50}}, '50'),